CP-violating Loop Effects in the Higgs Sector of the MSSM

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PACSnumbers1215Ff,1130Hv,1210Dm,1125Mj…

a r X i v :0803.2889v 2 [h e p -p h ] 14 J u l 2008Mapping Out SU (5)GUTs with Non-Abelian Discrete Flavor SymmetriesFlorian Plentinger ∗and Gerhart Seidl †Institut f¨u r Physik und Astrophysik,Universit¨a t W¨u rzburg,Am Hubland,D 97074W¨u rzburg,Germany(Dated:December 25,2013)We construct a class of supersymmetric SU (5)GUT models that produce nearly tribimaximal lepton mixing,the observed quark mixing matrix,and the quark and lepton masses,from discrete non-Abelian ﬂavor symmetries.The SU (5)GUTs are formulated on ﬁve-dimensional throats in the ﬂat limit and the neutrino masses become small due to the type-I seesaw mechanism.The discrete non-Abelian ﬂavor symmetries are given by semi-direct products of cyclic groups that are broken at the infrared branes at the tip of the throats.As a result,we obtain SU (5)GUTs that provide a combined description of non-Abelian ﬂavor symmetries and quark-lepton complementarity.PACS numbers:12.15.Ff,11.30.Hv,12.10.Dm,One possibility to explore the physics of grand uniﬁed theories (GUTs)[1,2]at low energies is to analyze the neutrino sector.This is due to the explanation of small neutrino masses via the seesaw mechanism [3,4],which is naturally incorporated in GUTs.In fact,from the perspective of quark-lepton uniﬁcation,it is interesting to study in GUTs the drastic diﬀerences between the masses and mixings of quarks and leptons as revealed by current neutrino oscillation data.In recent years,there have been many attempts to re-produce a tribimaximal mixing form [5]for the leptonic Pontecorvo-Maki-Nakagawa-Sakata (PMNS)[6]mixing matrix U PMNS using non-Abelian discrete ﬂavor symme-tries such as the tetrahedral [7]and double (or binary)tetrahedral [8]groupA 4≃Z 3⋉(Z 2×Z 2)and T ′≃Z 2⋉Q,(1)where Q is the quaternion group of order eight,or [9]∆(27)≃Z 3⋉(Z 3×Z 3),(2)which is a subgroup of SU (3)(for reviews see, e.g.,Ref.[10]).Existing models,however,have generally dif-ﬁculties to predict also the observed fermion mass hierar-chies as well as the Cabibbo-Kobayashi-Maskawa (CKM)quark mixing matrix V CKM [11],which applies especially to GUTs (for very recent examples,see Ref.[12]).An-other approach,on the other hand,is oﬀered by the idea of quark-lepton complementarity (QLC),where the so-lar neutrino angle is a combination of maximal mixing and the Cabibbo angle θC [13].Subsequently,this has,in an interpretation of QLC [14,15],led to a machine-aided survey of several thousand lepton ﬂavor models for nearly tribimaximal lepton mixing [16].Here,we investigate the embedding of the models found in Ref.[16]into ﬁve-dimensional (5D)supersym-metric (SUSY)SU (5)GUTs.The hierarchical pattern of quark and lepton masses,V CKM ,and nearly tribi-maximal lepton mixing,arise from the local breaking of non-Abelian discrete ﬂavor symmetries in the extra-dimensional geometry.This has the advantage that theFIG.1:SUSY SU (5)GUT on two 5D intervals or throats.The zero modes of the matter ﬁelds 10i ,5H,24H ,and the gauge supermul-tiplet,propagate freely in the two throats.scalar sector of these models is extremely simple without the need for a vacuum alignment mechanism,while of-fering an intuitive geometrical interpretation of the non-Abelian ﬂavor symmetries.As a consequence,we obtain,for the ﬁrst time,a realization of non-Abelian ﬂavor sym-metries and QLC in SU (5)GUTs.We will describe our models by considering a speciﬁc minimal realization as an example.The main features of this example model,however,should be viewed as generic and representative for a large class of possible realiza-tions.Our model is given by a SUSY SU (5)GUT in 5D ﬂat space,which is deﬁned on two 5D intervals that have been glued together at a common endpoint.The geom-etry and the location of the 5D hypermultiplets in the model is depicted in FIG.1.The two intervals consti-tute a simple example for a two-throat setup in the ﬂat limit (see,e.g.,Refs.[17,18]),where the two 5D inter-vals,or throats,have the lengths πR 1and πR 2,and the coordinates y 1∈[0,πR 1]and y 2∈[0,πR 2].The point at y 1=y 2=0is called ultraviolet (UV)brane,whereas the two endpoints at y 1=πR 1and y 2=πR 2will be referred to as infrared (IR)branes.The throats are supposed to be GUT-scale sized,i.e.1/R 1,2 M GUT ≃1016GeV,and the SU (5)gauge supermultiplet and the Higgs hy-permultiplets 5H and2neously broken to G SM by a 24H bulk Higgs hypermulti-plet propagating in the two throats that acquires a vac-uum expectation value pointing in the hypercharge direc-tion 24H ∝diag(−12,13,15i ,where i =1,2,3is the generation index.Toobtainsmall neutrino masses via the type-I seesaw mechanism [3],we introduce three right-handed SU (5)singlet neutrino superﬁelds 1i .The 5D Lagrangian for the Yukawa couplings of the zero mode fermions then readsL 5D =d 2θ δ(y 1−πR 1) ˜Y uij,R 110i 10j 5H +˜Y d ij,R 110i 5H +˜Y νij,R 15j5i 1j 5H +M R ˜Y R ij,R 21i 1j+h.c. ,(3)where ˜Y x ij,R 1and ˜Y x ij,R 2(x =u,d,ν,R )are Yukawa cou-pling matrices (with mass dimension −1/2)and M R ≃1014GeV is the B −L breaking scale.In the four-dimensional (4D)low energy eﬀective theory,L 5D gives rise to the 4D Yukawa couplingsL 4D =d 2θ Y u ij 10i 10j 5H +Y dij10i 5H +Y νij5i ∼(q i 1,q i 2,...,q i m ),(5)1i ∼(r i 1,r i 2,...,r im ),where the j th entry in each row vector denotes the Z n jcharge of the representation.In the 5D theory,we sup-pose that the group G A is spontaneously broken by singly charged ﬂavon ﬁelds located at the IR branes.The Yukawa coupling matrices of quarks and leptons are then generated by the Froggatt-Nielsen mechanism [21].Applying a straightforward generalization of the ﬂavor group space scan in Ref.[16]to the SU (5)×G A represen-tations in Eq.(5),we ﬁnd a large number of about 4×102ﬂavor models that produce the hierarchies of quark and lepton masses and yield the CKM and PMNS mixing angles in perfect agreement with current data.A distri-bution of these models as a function of the group G A for increasing group order is shown in FIG.2.The selection criteria for the ﬂavor models are as follows:First,all models have to be consistent with the quark and charged3 lepton mass ratiosm u:m c:m t=ǫ6:ǫ4:1,m d:m s:m b=ǫ4:ǫ2:1,(6)m e:mµ:mτ=ǫ4:ǫ2:1,and a normal hierarchical neutrino mass spectrumm1:m2:m3=ǫ2:ǫ:1,(7)whereǫ≃θC≃0.2is of the order of the Cabibbo angle.Second,each model has to reproduce the CKM anglesV us∼ǫ,V cb∼ǫ2,V ub∼ǫ3,(8)as well as nearly tribimaximal lepton mixing at3σCLwith an extremely small reactor angle 1◦.In perform-ing the group space scan,we have restricted ourselves togroups G A with orders roughly up to 102and FIG.2shows only groups admitting more than three valid mod-els.In FIG.2,we can observe the general trend thatwith increasing group order the number of valid modelsper group generally increases too.This rough observa-tion,however,is modiﬁed by a large“periodic”ﬂuctu-ation of the number of models,which possibly singlesout certain groups G A as particularly interesting.Thehighly populated groups would deserve further system-atic investigation,which is,however,beyond the scopeof this paper.From this large set of models,let us choose the groupG A=Z3×Z8×Z9and,in the notation of Eq.(5),thecharge assignment101∼(1,1,6),102∼(0,3,1),103∼(0,0,0),52∼(0,7,0),52↔4FIG.3:Eﬀect of the non-Abelian ﬂavor symmetry on θ23for a 10%variation of all Yukawa couplings.Shown is θ23as a function of ǫfor the ﬂavor group G A (left)and G A ⋉G B (right).The right plot illustrates the exact prediction of the zeroth order term π/4in the expansion θ23=π/4+ǫ/√2and the relation θ13≃ǫ2.The important point is that in the expression for θ23,the leading order term π/4is exactly predicted by thenon-Abelian ﬂavor symmetry G F =G A ⋉G B (see FIG.3),while θ13≃θ2C is extremely small due to a suppression by the square of the Cabibbo angle.We thus predict a devi-ation ∼ǫ/√2,which is the well-known QLC relation for the solar angle.There have been attempts in the literature to reproduce QLC in quark-lepton uniﬁed models [26],however,the model presented here is the ﬁrst realization of QLC in an SU (5)GUT.Although our analysis has been carried out for the CP conserving case,a simple numerical study shows that CP violating phases (cf.Ref.[27])relevant for neutri-noless double beta decay and leptogenesis can be easily included as well.Concerning proton decay,note that since SU (5)is bro-ken by a bulk Higgs ﬁeld,the broken gauge boson masses are ≃M GUT .Therefore,all fermion zero modes can be localized at the IR branes of the throats without intro-ducing rapid proton decay through d =6operators.To achieve doublet-triplet splitting and suppress d =5pro-ton decay,we may then,e.g.,resort to suitable extensions of the Higgs sector [28].Moreover,although the ﬂavor symmetry G F is global,quantum gravity eﬀects might require G F to be gauged [29].Anomalies can then be canceled by Chern-Simons terms in the 5D bulk.We emphasize that the above discussion is focussed on a speciﬁc minimal example realization of the model.Many SU (5)GUTs with non-Abelian ﬂavor symmetries,however,can be constructed along the same lines by varying the ﬂavor charge assignment,choosing diﬀerent groups G F ,or by modifying the throat geometry.A de-tailed analysis of these models and variations thereof will be presented in a future publication [30].To summarize,we have discussed the construction of 5D SUSY SU (5)GUTs that yield nearly tribimaximal lepton mixing,as well as the observed CKM mixing matrix,together with the hierarchy of quark and lepton masses.Small neutrino masses are generated only by the type-I seesaw mechanism.The fermion masses and mixings arise from the local breaking of non-Abelian ﬂavor symmetries at the IR branes of a ﬂat multi-throat geometry.For an example realization,we have shown that the non-Abelian ﬂavor symmetries can exactly predict the leading order term π/4in the sum rule for the atmospheric mixing angle,while strongly suppress-ing the reactor angle.This makes this class of models testable in future neutrino oscillation experiments.In addition,we arrive,for the ﬁrst time,at a combined description of QLC and non-Abelian ﬂavor symmetries in SU (5)GUTs.One main advantage of our setup with throats is that the necessary symmetry breaking can be realized with a very simple Higgs sector and that it can be applied to and generalized for a large class of uniﬁed models.We would like to thank T.Ohl for useful comments.The research of F.P.is supported by Research Train-ing Group 1147“Theoretical Astrophysics and Particle Physics ”of Deutsche Forschungsgemeinschaft.G.S.is supported by the Federal Ministry of Education and Re-search (BMBF)under contract number 05HT6WWA.∗********************************.de †**************************.de[1]H.Georgi and S.L.Glashow,Phys.Rev.Lett.32,438(1974);H.Georgi,in Proceedings of Coral Gables 1975,Theories and Experiments in High Energy Physics ,New York,1975.[2]J.C.Pati and A.Salam,Phys.Rev.D 10,275(1974)[Erratum-ibid.D 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Computer-Vision计算机视觉英文ppt

At the same time, AI MIT laboratory has attracted many famous scholars from the world to participate in the research of machine vision,which included the theory of machine vision , algorithm and design of system .
Its mainstream research is divided into three stages:
Stage 1: Research on the visual basic method ,which take the model world as the main object;
Stage 2: Research on visual model ,which is based on the computational theory;
the other is to rebuild the three dimensional object according to the two-dimensional projection images .
History of computer vision
1950s: in this period , statistical pattern recognition is most applied in computer vision , it mainly focuse on the analysis and identification of two-dimensional image,such as: optical character recognition, the surface of the workpiece, the analysis and interpretation of the aerial image.

专题05 阅读理解D篇(2024年新课标I卷) (专家评价+三年真题+满分策略+多维变式) 原卷版

《2024年高考英语新课标卷真题深度解析与考后提升》专题05阅读理解D篇（新课标I卷）原卷版(专家评价+全文翻译+三年真题+词汇变式+满分策略+话题变式)目录一、原题呈现P2二、答案解析P3三、专家评价P3四、全文翻译P3五、词汇变式P4(一)考纲词汇词形转换P4(二)考纲词汇识词知意P4(三)高频短语积少成多P5(四)阅读理解单句填空变式P5(五)长难句分析P6六、三年真题P7(一)2023年新课标I卷阅读理解D篇P7(二)2022年新课标I卷阅读理解D篇P8(三)2021年新课标I卷阅读理解D篇P9七、满分策略（阅读理解说明文）P10八、阅读理解变式P12 变式一：生物多样性研究、发现、进展6篇P12变式二：阅读理解D篇35题变式（科普研究建议类）6篇P20一原题呈现阅读理解D篇关键词: 说明文;人与社会;社会科学研究方法研究;生物多样性; 科学探究精神;科学素养In the race to document the species on Earth before they go extinct, researchers and citizen scientists have collected billions of records. Today, most records of biodiversity are often in the form of photos, videos, and other digital records. Though they are useful for detecting shifts in the number and variety of species in an area, a new Stanford study has found that this type of record is not perfect.“With the rise of technology it is easy for people to make observation s of different species with the aid of a mobile application,” said Barnabas Daru, who is lead author of the study and assistant professor of biology in the Stanford School of Humanities and Sciences. “These observations now outnumber the primary data that comes from physical specimens(标本), and since we are increasingly using observational data to investigate how species are responding to global change, I wanted to know: Are they usable?”Using a global dataset of 1.9 billion records of plants, insects, birds, and animals, Daru and his team tested how well these data represent actual global biodiversity patterns.“We were particularly interested in exploring the aspects of sampling that tend to bias (使有偏差) data, like the greater likelihood of a citizen scientist to take a picture of a flowering plant instead of the grass right next to it,” said Daru.Their study revealed that the large number of observation-only records did not lead to better global coverage. Moreover, these data are biased and favor certain regions, time periods, and species. This makes sense because the people who get observational biodiversity data on mobile devices are often citizen scientists recording their encounters with species in areas nearby. These data are also biased toward certain species with attractive or eye-catching features.What can we do with the imperfect datasets of biodiversity?“Quite a lot,” Daru explained. “Biodiversity apps can use our study results to inform users of oversampled areas and lead them to places – and even species – that are not w ell-sampled. To improve the quality of observational data, biodiversity apps can also encourage users to have an expert confirm the identification of their uploaded image.”32. What do we know about the records of species collected now?A. They are becoming outdated.B. They are mostly in electronic form.C. They are limited in number.D. They are used for public exhibition.33. What does Daru’s study focus on?A. Threatened species.B. Physical specimens.C. Observational data.D. Mobile applications.34. What has led to the biases according to the study?A. Mistakes in data analysis.B. Poor quality of uploaded pictures.C. Improper way of sampling.D. Unreliable data collection devices.35. What is Daru’s suggestion for biodiversity apps?A. Review data from certain areas.B. Hire experts to check the records.C. Confirm the identity of the users.D. Give guidance to citizen scientists.二答案解析三专家评价考查关键能力，促进思维品质发展2024年高考英语全国卷继续加强内容和形式创新，优化试题设问角度和方式，增强试题的开放性和灵活性，引导学生进行独立思考和判断，培养逻辑思维能力、批判思维能力和创新思维能力。

刺激-反应联结学习在项目特异性比例一致效应中的作用

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效应。研究者认为，可能存在局部的、项目特异性的认知控制机制，可以根据单个项目的比例偏置情况选择性地进行注意资源分配从而影响不同项目的反应（Jacoby et al., 2003）。
然而，注意调节理论近来受到了其他研究的挑战（Schmidt & Besner, 2008; Schmidt & Lemercier, 2019）。Schmidt 和 Besner 认为，ISPC 效应中比例一致性与刺激–反应的可能性混合在一起，可以用更经济的可能性学习来解释这一效应。该研究提出了可能性学习假说（contingency learning hypothesis），表示认知控制不是必要的，被试完全可以通过学习发现刺激无关维度与正确反应的可能性关系，并基于此预测正确的反应。在冲突任务中，一致试次占多数时，刺激常常伴随着一致的任务无关的刺激属性，这一属性有很大可能性可以去预测正确的反应，而多数试次为不一致时，被试可能根据伴随的不一致的任务无关刺激属性去预测反应（Schmidt & Lemercier, 2019）。这一策略可以加快一致或不一致试次的反应，从而产生 ISPC 效应。可能性学习假说基于刺激–反应（stimulus-response, S-R）之间的联结解释了 ISPC 效应，是 S-R 联结学习的一种方式（Schmidt, 2013）。
心理与行为研究 2021，19(3)：326~333 Studies of Psychology and Behavior
刺激–反应联结学习在项目特异性比例一致效应中的作用 *
夏天生1 谭玲2
(1 广东工业大学艺术与设计学院，广州 510090) (2 广东工业大学管理学院，广州 510520)

基于混沌系统与提升小波的抗剪切攻击的彩色图像盲水印算法

序列；提升小波；抗剪切攻击
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基混沌统与提升小波的抗剪切攻击的于系彩色图像盲水印算法
赵玉霞，２
（．商洛学院计算机科学系，陕西商洛７６０；２１２００．西北大学信息科学与技术学院，陕西西安７０６１０９）
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Ｅｐｒｍｅｔｉｄｃｔｈｔｔｅａｇｒｈｈｓｈｇｆｃｅｃ，ｔｏｇｒｂｓｎｓｎｅｕｉ，ｄｘｅｉｎｓｎｉａｅｔａｈｌｏｔｍａｉｈｅｉｎｙｓｎｏｕｔｅｓａｄｓｃｒｔａｉｉｒｙｎｐｒｃｌｒｙｉｃｎｐｏｅｔｏｓｅｒｒｎｆｒａｉｎａｔｃ．ａｔｕａｌａｒｔｃｍｈａａｓｏｉｔｒｆｔｍｔｔｋｏａＫｅｒｓｏｕｅｐｌａｉｎｌｄｗａｅｍａｋｎｌｏｔｍ；ｃａｓｓｑｅｃｓＬＷＴ；ｙｗｏｄ：ｃｍｐｔｒａｐｉｔ；ｂｉｔｒｒｉｇａｇｒｈｃｏｎｉｈｏｅｕｎｅ；ｐｏｅｔｇｓｅｒｔａｓｏａｉｎａｔｃｒｔｃｉｈａｎｆｒｔｔｋｎｒｍｏａ

基于拉普拉斯特征映射的鲁棒视频哈希方法

ＲｏｕｔｉｅａｈｎａｅｎＬａｌｃａｇｎｐｂｓｖｄｏｈｓｉｇｂｓｄｏｐａｉｎＥｉｅｍａｓ
ＮＩｕｓａＱＩｉｎｐｎ。Ｑｒｅｇｌ２ＥＸｉ－ｈｎ，ＡＯＪ —ｉｇ，ａＮＦｎ —ｎｉ
ＡｂｔａｔｂｓｖｄｏｈｓｉｇｆｒｉｅｏｙｄｔｃｏａｅｎＬｐａｉｉｅｍａｓ（Ｅｉｐｏｏｅ．Ｉｉｍｅｏ，ｋｙｓｃ：ＡｒｕｔｉｅａｈｎｄｏｃｐｅｅｔｎｂｓｄｏａｌｃａＥｇｎｈｈ
（．山东财政学院计算机信息工程学院，山东济南２０１；２１５０４．山东大学信息科学与工程学院，山东济南２００；３５１０．山东师范大学传播学院，山东济南２０１）５０４
摘要：针对视频拷贝检测问题，出了基于拉普拉斯特征映射（ａｌｉｉｎｐ，Ｅ的视频哈希方法，提ＬｐａａＥｇｍａｓＬ）ｃｎｅ该方法利用视频
明，方法具有较好的鲁棒性和区分性。该关键词：拉普拉斯特征映射；视频哈希；拷贝检测；鲁棒性；区分性
中图法分类号：Ｐ９Ｔ３１
文献标识码：Ａ
文章编号：００７２（１１３９．１０．０４２１１７９００）－４
层析成像技术和服从均匀分布的向量对视频进行镜头分割和关键帧提取，以高阶累计量作为视频在高维空间的特征，并利用ＬＥ进行降维，到视频在三维空间中的轨迹，得利用三维空间中点的范数构造视频哈希来实现视频拷贝检测。实验结果表

CP Asymmetries in Higgs decays to ZZ at the LHC

a r X i v :0708.3612v 1 [h e p -p h ] 27 A u g 2007CP Asymmetries in Higgs decays to ZZ at the LHCRohini M.Godbole 1,David ler 2,M.Margarete M¨u hlleitner 3,41Centre for High Energy Physics,Indian Institute of Science,Bangalore,560012,India.2Dept.of Physics and Astronomy,University of Glasgow,Glasgow G128QQ,U.K.3Theory Division,Physics Department,CERN,CH-1211Geneva 23,Switzerland.4Laboratoire d’Annecy-Le-Vieux de Physique Th´e orique,LAPTH,France.Abstract.We examine the eﬀect of a general HZZ coupling through a study of the Higgs decay to leptons via Z bosons at the LHC.We discuss various methods for placing limits on additional couplings,including measurement of the partial width,threshold scans,and asymmetries constructed from angular observables.We ﬁnd that only the asymmetries provide a deﬁnitive test of additional couplings.We further estimate the signiﬁcances they provide.1.IntroductionThe veriﬁcation of the Higgs mechanism as the cause of electroweak symmetry breaking and the discovery of the Higgs boson is the next big goal of particle physics.However,it is not enough to simply ﬁnd a new resonance in the Higgs search channels at the next generation of colliders.One must ensure that this resonance is indeed the Higgs boson by measuring its properties:its CP and spin,to demonstrate its predicted scalar nature;its couplings to known particles,to verify that these couplings are proportional to the particle’s mass;and the Higgs self couplings,in order to reconstruct the Higgs potential itself.This will be a challenging programme and will not be fully realised at the Large Hadron Collider (LHC)(e.g.the quartic Higgs self coupling will be out of reach).However,such an analysis will be crucial in our investigation of electroweak symmetry breaking in scenarios where the suspected Higgs boson is all we ﬁnd at the LHC,as well as scenarios where new physics is discovered.In the former case,testing for deviations from the Standard Model (SM)may provide clues to resolving some of the SM’s long standing problems;in the latter case,the Higgs boson properties will provide essential information on the nature of the new physics.It is interesting to note that the Higgs boson’s CP (and spin)is intimately related to its couplings to other SM particles,since its scalar or pseudoscalar nature allow or forbid certain tensor structures in the Higgs boson couplings.In this report,we investigate the tensor structure of the HZZ vertex in order to shed some light on the Higgs boson’s CP.We write down the most general tensor vertex for this coupling and investigate how the additional terms inﬂuence the decay H →ZZ (∗)→4leptons at the LHC.For a more detailed description of this analysis,see Ref.[1].The most general vertex for a spinless particle coupling to a pair of Z bosons,with four-momenta q 1and q 2,is given by,V µνHZZ=igm Zm 2Z+c ǫµναβp αk βwhere p=q1+q2and k=q1−q2,θW denotes the weak-mixing angle andǫµναβis the totally antisymmetric tensor withǫ0123=1.The CP conserving tree-level Standard Model coupling is recovered for a=1and b=c=0.Terms containing a and b are associated with the coupling of a CP-even Higgs,while that containing c is associated with that of a CP-odd Higgs boson.The simulanteous appearance of a non-zero a(and/or b)together with a non-zero c would lead to CP violation.In general these parameters can be momentum-dependent form factors that may be generated from loops containing new heavy particles or equivalently from the integration over heavy degrees of freedom giving rise to higher dimensional operators.The form factors b and c may,in general,be complex, but since an overall phase will not aﬀect the observables studied here,we are free to adopt the convention that a is real.2.The total widthOne method of investigating the tensor structure of the HZZ coupling is to examine the threshold behaviour of the decay H→ZZ∗[2].Notice that the additional terms in the vertexwidth on the virtuality of the most virtual Z boson.width from the SM prediction.Alternatively,one could examine the magnitude of the total decay width for H→ZZ∗→4leptons to see if it diﬀers from the SM.For the vertex of Equation1,the dependence on the coeﬃcients a,b and c is given by,∂2ΓHm4H +|b|2m4H4+|c|28q21q22m2Zβ2 m4H ,(2)whereβis the usual Lorentz boost factor for the Z-bosons.(Notice that the only term with a linearβdependence(from the phase space)is proportional to a2,illustrating the principle described above for the threshold scan.)If additional terms are present one expects them toincrease or decrease the width according to this equation.We used the ATLAS study of Ref.[3,4] (including cuts and eﬃciencies)to estimate the number of signal and background events for the SM and CP-violating scenarios(scaling the signal according to Equation2).In Figure2we plot the number of standard deviations from the SM that the CP-violating scenario would imply,for a150GeV Higgs boson and an integrated luminosity of300fb−1(we set b=0for simplicity). The white area represents scenarios where the signiﬁcance of the deviation is less than3σ,the light blue/grey region represents a3−5σdeviation,while the dark blue/grey region represents a greater than5σdeviation.This measurement would allow one to rule out much of the a−|c| parameter space,but does not allow one to deﬁnitively rule out(or place signiﬁcant limits on) the CP-odd coupling|c|.A SM-like rate is perfectly consistent with a large value of|c|and a small value of a.3.Asymmetries as a probe of CP violationTo deﬁnitively ascertain whether or not extra tensor structures are present in the HZZ vertex one is better served by measuring asymmetries which vanish when such terms are absent.Such an asymmetry can be constructed from an observable,O,based on the angles of theﬁnal state leptons,Γ(O>0)−Γ(O<0)A=。

Nature Research Reporting Summary说明书

October 2018Corresponding author(s):Sinem K. Saka, Yu Wang, Peng YinLast updated by author(s):June 05, 2019Reporting SummaryNature Research wishes to improve the reproducibility of the work that we publish. This form provides structure for consistency and transparency in reporting. For further information on Nature Research policies, see Authors & Referees and the Editorial Policy Checklist .StatisticsFor all statistical analyses, confirm that the following items are present in the figure legend, table legend, main text, or Methods section.The exact sample size (n ) for each experimental group/condition, given as a discrete number and unit of measurement A statement on whether measurements were taken from distinct samples or whether the same sample was measured repeatedlyThe statistical test(s) used AND whether they are one- or two-sided Only common tests should be described solely by name; describe more complex techniques in the Methods section.A description of all covariates tested A description of any assumptions or corrections, such as tests of normality and adjustment for multiple comparisons A full description of the statistical parameters including central tendency (e.g. means) or other basic estimates (e.g. regression coefficient) AND variation (e.g. standard deviation) or associated estimates of uncertainty (e.g. confidence intervals)For null hypothesis testing, the test statistic (e.g. F , t , r ) with confidence intervals, effect sizes, degrees of freedom and P value notedGive P values as exact values whenever suitable.For Bayesian analysis, information on the choice of priors and Markov chain Monte Carlo settingsFor hierarchical and complex designs, identification of the appropriate level for tests and full reporting of outcomesEstimates of effect sizes (e.g. Cohen's d , Pearson's r ), indicating how they were calculatedOur web collection on statistics for biologists contains articles on many of the points above.Software and codePolicy information about availability of computer codeData collection Commercial softwares licensed by microscopy companies were utilized: Zeiss Zen 2012 (for LSM 710), Leica LAS AF (for Leica SP5), ZeissZen 2.3 Pro Blue edition (for LZeiss Axio Observer Z1), Olympus VS-ASW (for Olympus VS120), PerkinElmer Phenochart (version 1.0.2) .Data analysis Open-source Python (3.6.5), TensorFlow (1.12.0), and Deep Learning packages have been utilized for machine learning-based nucleiidentification (the algorithm and code is available at https:///HMS-IDAC/UNet). We used Matlab (2017b) for watershed-based nuclear segmentation using the identified nuclear contours. Python 3.6 was used for the FWHM calculations, as well as plotting ofhistograms. We used MATLAB and the Image Processing Toolbox R2016a (The MathWorks, Inc., Natick, Massachusetts, United States)for quantifications in mouse retina sections and for Supplementary Fig. 4. We utilized Cell Profiler 3.1.5 for the quantifications of signalamplification in FFPE samples in Figure 2 and 3. FIJI (version 2.0.0-rc-69/1.52n) was utilized for ROI selections and format conversions.HMS OMERO (version 5.4.6.21) was used for viewing images and assembling figure panels.For manuscripts utilizing custom algorithms or software that are central to the research but not yet described in published literature, software must be made available to editors/reviewers. We strongly encourage code deposition in a community repository (e.g. GitHub). See the Nature Research guidelines for submitting code & software for further information.DataPolicy information about availability of dataAll manuscripts must include a data availability statement . This statement should provide the following information, where applicable:- Accession codes, unique identifiers, or web links for publicly available datasets- A list of figures that have associated raw data- A description of any restrictions on data availabilityData and Software Availability: The data and essential custom scripts for image processing will be made available from the corresponding authors P.Y.(**************.edu),S.K.S.(***********************.edu),andY.W.(********************.edu)uponrequest.Thedeeplearningalgorithmandtestdataset for automated identification of nuclear contours in tonsil tissues is available on https:///HMS-IDAC/UNet . The MATLAB code for nuclear segmentation isOctober 2018available on: https:///HMS-IDAC/SABERProbMapSegmentation .Field-specific reportingPlease select the one below that is the best fit for your research. If you are not sure, read the appropriate sections before making your selection.Life sciencesBehavioural & social sciences Ecological, evolutionary & environmental sciencesFor a reference copy of the document with all sections, see /documents/nr-reporting-summary-flat.pdfLife sciences study design All studies must disclose on these points even when the disclosure is negative.Sample size Each FFPE experiment batch were performed on consecutive sections from the same source, each containing over 600,000 cells. Due to largenumber of single cells with tens of distinct germinal center morphologies being present in each section, ROIs from different parts of a wholesection was used for quantification of signal improvement for each condition (consecutive sections were used for all the conditions of onequantification experiment). Number of ROIs are noted in the respective figure legends. For quantifications in retina samples, due toconserved staining morphology and low sample-to-sample variability n = 6 z-stacks were acquired from at least 2 retina sections. ForSupplementary Fig. 4, minimum 5 z-stacks were acquired for each condition to collect images of 18-45 cells. Number of cells are reported in the graphs.Data exclusions Parts of the FFPE tissue sections were excluded from analysis due to automated imaging related aberrations (out-of-focus areas) or tissuepreparation aberrations (folding of the thin sections at the edges, or uneven thickness at the edge areas). For FWHM calculations inSupplementary Fig. 2, ROIs that yield lineplots with more than one automatically detected peak were discarded to avoid deviations due tomultiple peaks. For Supplementary Fig. 4 cells in the samples were excluded when an external bright fluorescent particle (dust speck, dye aggregate etc.) coincided with the nuclei (as confirmed by manual inspection of the images). The exclusion criteria were pre-established.Replication Each FFPE experiment batch were performed on consecutive sections from the same source, each containing over 600,000 cells. Forevaluation and quantification of our method, multiple biological replicates were not accumulated in order to avoid the error that would beintroduced by the natural biological and preparation variation, and to avoid unnecessary use of human tissue material. In the case of themouse retina quantifications a minimum of two distinct retinal sections were imaged, and each experiment was performed at least twice. ForSupplementary Fig. 4 dataset, 16 different conditions were prepared and each were imaged multiple times (before linear, after linear, beforebranch, after branch). Although the data was not pooled together for the statistics reported in the figure, low cell-to-cell variability was observed and high consistency was seen across the samples for comparable conditions, suggesting low sample to sample variability.Randomization Randomization was not necessary for this study.Blinding Blinding was not possible as experimental conditions were mostly evident from the image data.Reporting for specific materials, systems and methodsWe require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material, system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response.AntibodiesAntibodies used The full list is also available in Supplementary Information, Supplementary Table 4.Ki-67 Cell Signaling #9129, clone: D3B5 (formulated in PBS, Lot: 2), diluted 1:100-1:250 after conjugationCD8a Cell Signaling #85336 clone: D8A8Y (formulated in PBS, Lot: 4) diluted 1:150 after conjugationPD-1 Cell Signaling #43248, clone: EH33 (formulated in PBS, Lot: 2), diluted 1:150 after conjugationIgA Jackson ImmunoResearch #109-005-011 (Lot: 134868), diluted 1:150 after conjugationCD3e Cell Signaling #85061 clone: D7A6E(TM) XP(R) (formulated in PBS, Lot:2), diluted 1:150 after conjugationIgM Jackson ImmunoResearch #709-006-073 (Lot: 133627), diluted 1:150 after conjugationLamin B Santa Cruz sc-6216 clone:C-20, (Lot: E1115), diluted 1:100Alpha-Tubulin ThermoFisher #MA1-80017 (multiple lots), diluted 1:50 after conjugationCone arrestin Millipore #AB15282 (Lot: 2712407), diluted 1:100 after conjugationGFAP ThermoFisher #13-0300 (Lot: rh241999), diluted 1:50 after conjugationSV2 HybridomaBank, Antibody Registry ID: AB_2315387, in house production, diluted 1:25 after conjugationPKCα Novus #NB600-201, diluted 1:50 after conjugationCollagen IV Novus #NB120-6586, diluted 1:50 after conjugationRhodopsin EnCor Bio #MCA-A531, diluted 1:50 after conjugationCalbindin EnCor Bio #MCA-5A9, diluted 1:25 after conjugationVimentin Cell Signaling #5741S, diluted 1:50 after conjugationCalretinin EnCor Bio #MCA3G9, diluted 1:50 after conjugationVLP1 EnCor Bio #MCA-2D11, diluted 1:25 after conjugationBassoon Enzo ADI-VAM-#PS003, diluted 1:500Homer1b/c ThermoFisher #PA5-21487, diluted 1:250SupplementaryAnti-rabbit IgG (to detect Ki-67 and Homer1b/c indirectly) Jackson ImmunoResearch # 711-005-152 (Multiple lots), 1:90 afterconjugationAnti-mouse IgG (to detect Bassoon indirectly) Jackson ImmunoResearch #715-005-151) (Multiple lots), diluted 1:100 afterconjugationAnti-goat IgG (to detect Lamin B indirectly) Jackson ImmunoResearch # 705-005-147) (Lot: 125860), diluted 1:75 afterconjugationAlternative antibodies used to validate colocalization of VLP1 and Calretinin in Supplementary Fig. 8d-f:Calretinin (SantaCruz #SC-365956; EnCor Bio #CPCA-Calret; EnCor Bio #MCA-3G9 AP), VLP1 (EnCor Bio #RPCA-VLP1; EnCor Bio#CPCA-VLP1; EnCor Bio #MCA-2D11). All diluted 1:100.Fluorophore-conjugated secondary antibodies used for reference imaging:anti-rat-Alexa647 (ThermoFisher #A-21472, 1:200), anti-rabbit-Alexa488 (ThermoFisher #A-21206, 1:200), anti-rabbit-Atto488(Rockland #611-152-122S, Lot:33901, 1:500), anti-mouse-Alexa647 (ThermoFisher #A-31571, 1:400), anti-goat-Alexa647(ThermoFisher # A-21447, 1:200), anti-rabbit-Alexa647 (Jackson ImmunoResearch, 711-605-152, Lot: 125197, 1:300).Validation All antibodies used are from commercial sources as described. Only antibodies that have been validated by the vendor with in vitro and in situ experiments (for IHC and IF, with images available on the websites) and/or heavily used by the community withpublication in several references were used. The validation and references for each are publicly available on the respectivevendor websites that can reached via the catalog numbers listed above. In our experiments, IF patterns matched the distributionof cell types these antibodies were expected to label based on the literature both before and after conjugation with DNA strands. Eukaryotic cell linesPolicy information about cell linesCell line source(s)BS-C-1 cells and HeLa cellsAuthentication Cell lines were not authenticated (not relevant for the experiment or results)Mycoplasma contamination Cell lines were not tested for mycoplasma contamination (not relevant for the experiment or results)Commonly misidentified lines (See ICLAC register)No commonly misidentified cell lines were used.October 2018Animals and other organismsPolicy information about studies involving animals; ARRIVE guidelines recommended for reporting animal researchLaboratory animals Wild-type CD1 mice (male and female) age P13 or P17 were used for retina harvest.Wild animals The study did not involve wild animals.Field-collected samples The study did not involve samples collected from the field.Ethics oversight All animal procedures were in accordance with the National Institute for Laboratory Animal Research Guide for the Care and Useof Laboratory Animals and approved by the Harvard Medical School Committee on Animal Care.Note that full information on the approval of the study protocol must also be provided in the manuscript.Human research participantsPolicy information about studies involving human research participantsPopulation characteristics We have only used exempt tissue sections for technical demonstration, since we do not derive any biological conclusions, thepopulation characteristics is not relevant for this methodological study.Recruitment Not relevant for this study.Ethics oversight Human specimens were retrieved from the archives of the Pathology Department of Beth Israel Deaconess Medical Centerunder the discarded/excess tissue protocol as approved in Institutional Review Board (IRB) Protocol #2017P000585. Informedinform consent was waived on the basis of minimal risk to participants (which is indirect and not based on prospectiveparticipation by patients).Note that full information on the approval of the study protocol must also be provided in the manuscript.October 2018。

Weak Interactions of Light Flavours

2Leabharlann Standard Model
LSM = LH (φ) + LG (W, Z, G) + Higgs Gauge ¯ / ψ+ ψiD
ψ=fermions ψ,ψ′ =fermions
The Standard Model Lagrangian has four parts: ¯ ′ gψψ′ ψφψ Yukawa
QCD and QED conserve C,P,T separately. Local Field theory by itself implies CPT. The fermion and Higgs2 part of the SM-lagrangian conserves CP and T as well. The only part that violates CP and as a consequence also T is the Yukawa part. The Higgs part is responsible for two parameters, the gauge part for three and the HiggsFermion part contains in principle 27 complex parameters, neglecting Yukawa couplings to neutrinos. Luckily most of the 54 real parameters in the Yukawa sector are unobservable. After diagonalizing the lepton sector there only the three charged lepton masses remain. The quark sector can be similarly diagonalized leading to 6 quark masses, but some parts remain in the diﬀerence between weak interaction eigenstates and mass-eigenstates. The latter is conventionally put in the couplings of the charged W -boson, which is given by Vud Vus Vub dα g α − uα cα t γ µ (1 − γ5 ) Vcd Vcs Vcb sα − √ Wµ 2 2 V V V b

对光照变化鲁棒的快速关键点提取与匹配

（江苏省图像处理与图像通信重点实验室，南京２００）１０３（南京邮电大学通信与信息工程学院，南京２００）１０３（南京邮电大学地理与生物信息学院，南京２００）１０３
（东南大学影像科学与技术实验室，京２０９）南１０６
照变化具有较好的适应性．
关键词：关键点提取；征匹配；照变化；方差描述子；特光协积分图像
中图分类号：Ｐ９Ｔ３１文献标志码：Ａ文章编号：１０００（０２０－４３００１— ５５２１）３０１－６
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零工工作者感知算法控制对工作投入的影响机制研究——基于认知和情感的双路径模型

第3期(总第389期)2024年3月商㊀业㊀经㊀济㊀与㊀管㊀理JOURNAL OF BUSINESS ECONOMICS No.3(General No.389)Mar.2024收稿日期:2023-12-08基金项目:国家自然科学基金项目如何扬长避短 ?越轨创新对多主体的双刃剑效应㊁人力资源管理干预机制及系统动态过程研究 (72172032);国家社会科学基金项目机器情感学习对人机协同双路径作用和养老陪护服务供需平衡的整合效应研究 (23BGL239);辽宁省社会科学规划基金项目数字化㊁服务化背景下的辽宁制造企业绩效提升战略研究 (L21BGL019);河北省自然科学基金项目服务化㊁数字化及其融合战略对制造企业绩效的影响研究 (G2021501006)作者简介:张兰霞,女,教授,博士生导师,管理学博士,主要从事组织行为与人力资源管理研究;李佳敏(通讯作者),男,博士研究生,主要从事组织行为与人力资源管理研究;毛孟雨,男,博士研究生,主要从事组织行为与人力资源管理研究㊂零工工作者感知算法控制对工作投入的影响机制研究基于认知和情感的双路径模型张兰霞,李佳敏,毛孟雨(东北大学工商管理学院,辽宁沈阳110169)摘㊀要:算法的快速发展及其在管理活动中的应用正改变着员工的工作方式,给组织管理实践带来了新的挑战㊂目前却少有研究关注员工感知算法控制对其工作投入的影响机制㊂文章依据资源保存理论,基于认知和情感的视角,构建了感知算法控制对工作投入影响的双路径模型,并检验了认知负荷和情绪耗竭的中介作用以及算法透明度的调节作用㊂针对397名零工工作者两阶段的调查分析发现:感知算法控制显著负向影响工作投入;认知负荷和情绪耗竭不仅在感知算法控制和工作投入之间起中介作用,而且在感知算法控制和工作投入之间起链式中介作用;算法透明度不仅调节了感知算法控制与认知负荷和情绪耗竭间的关系,还调节了认知负荷和情绪耗竭的中介作用㊂这不仅丰富了算法管理领域的实证研究成果,也为相关组织开展科学的员工管理实践提供了参考和借鉴㊂关键词:感知算法控制;工作投入;算法透明度;资源保存理论中图分类号:F270㊀㊀文献标志码:A㊀㊀文章编号:10002154(2024)03004712DOI:10.14134/33-1336/f.2024.03.004Impact of Perceived Algorithmic Control of Gig Workers on Work Engagement :A Dual-Pathway Model Based on Cognitive and Affective FactorsZHANG Lanxia,LI Jiamin,MAO Mengyu (School of Business Administration ,Northeastern University ,Shenyang 110169,China )Abstract ︰The rapid development of algorithms and their application in management activities are changing the way employees work and bringing new challenges to organizational management practices.There is currently little research focusing on the mechanisms by which employees perceived algorithmic control and how it impacts their work engagement.This study is based on the conservation of resources theory and constructs a dual-path model of the impact of perceived algorithmic control on work engagement from cognitive and emotional perspectives.It examines the mediating role of cognitive load and emotional exhaustion,as well as the moderating role of algorithm transparency.From a two-stage survey analysis of 397gig workers this study finds that perceived algorithmic control significantly negatively affects work engagement.Cognitive load and emotional exhaustion not only play mediation effects in the relationships between perceived algorithmic control and work engagement,but also play chain mediation roles in the relationships between perceived algorithmic control and work engagement.In addition,algorithm transparency not only moderates the84商㊀业㊀经㊀济㊀与㊀管㊀理2024年effects of perceived algorithmic control on cognitive load and emotional exhaustion,but also moderates the mediating role of cognitive load and emotional exhaustion.This study enriches the empirical research results in the field of algorithm management,and provides a basis for relevant organizations to develop scientific employee management measures.Key words︰perceived algorithmic control;work engagement;algorithm transparency;conservation of resources theory一、引㊀言数字化促进了零工经济在全球范围内的发展,尤其在中国,以网约车司机㊁外卖小哥为代表的零工工作者依托在线劳动平台实现就业,推动了我国经济的发展[1]㊂目前,已有许多企业依靠平台算法管理零工工作者,使算法管理在管理实践中逐步得到推广[2]㊂在企业应用算法的过程中,零工工作者不仅在工作中经常感知到算法对自身的监控,而且他们的收入和绩效都是通过算法反馈的数据得到的,感知算法控制对零工工作者的重要影响逐渐凸显[3]㊂因此,零工工作者感知算法控制逐渐得到组织管理者与学者们的关注,在学术研究中取得了许多成果㊂感知算法控制是指员工对于算法如何通过规范指导㊁追踪评估和行为约束对其提供在线劳动服务的过程进行实时动态控制的综合感知[4]㊂通过文献梳理发现,相关学者对感知算法控制的结果变量进行了初步探讨,并且发现感知算法控制可以影响员工的行为㊁绩效和健康等[5-6]㊂总的来说,这些研究深化了人们对感知算法控制结果变量的理解,也为组织如何有效地采取措施应对感知算法控制提供了可靠的管理启示㊂但遗憾的是,这些研究都忽视了感知算法控制对零工工作者工作状态的影响㊂事实上,算法正在逐步改变着员工的工作状态㊂工作状态不仅对员工的身心健康和工作行为有重要影响,还会影响企业绩效㊂因此,探究感知算法控制对员工工作状态的影响是十分必要的㊂在对员工工作状态的零星研究中,学者们分别检验了感知算法控制对员工的认知和情感的影响㊂例如,孙锐等[6]发现感知算法控制会影响零工工作者的情绪耗竭㊂但是,目前的研究缺少对员工的认知和情感的整合㊂事实上,感知算法控制对员工的认知和情感都有重要影响,基于认知和情感的算法管理研究有待学者整合㊂此外,有学者认为个体认知的变化会进一步导致情感的变化[7]㊂因此,本文进一步考虑认知到情感的链式中介作用㊂特别地,已有研究发现算法控制对认知和情感的影响存在研究结论不一致的地方㊂例如,感知算法控制对工作投入的影响不是简单的线性关系,感知算法控制对情绪耗竭存在双刃剑效应[6]等㊂本文认为出现不一致研究结论的原因是学者们缺乏对感知算法控制边界条件的认知,因此需要理论界进一步揭示感知算法控制的边界条件㊂工作投入作为一种以活力㊁奉献等特质为代表的积极工作状态,是连接个体特征㊁工作因素和工作绩效的纽带[8]㊂本文选取工作投入作为员工的工作状态变量,探讨感知算法控制对员工工作状态的影响机制㊂资源保存理论为解释感知算法控制对工作投入的影响机制提供了新的理论视角㊂该理论认为,个体具有保护自身资源的动机,现有资源存量会进一步影响他们的工作态度与行为[9]㊂由于算法对零工工作者进行全方位的监控,他们在感受到这种控制后,会感受到工作压力㊁紧张和不安[4]㊂基于资源保存理论,感知算法控制会使零工工作者快速损耗资源,导致资源短缺㊂这些损失的资源可以表现为零工工作者在感知算法控制后产生的消极心理状态,如心理认知和情感状态等[2-3]㊂一方面,感受到算法控制的零工工作者既希望按时完成工作,也会担心自己在工作过程中由于争分夺秒完成任务而出现危险,这就会经历矛盾的认知过程,消耗自身认知资源,产生认知负荷;另一方面,零工工作者在感受到算法的实时监控和追踪后会产生工作压力,进而消耗自己的情绪资源,导致情绪耗竭[9]㊂因此,认知负荷是一种消极认知,情绪耗竭是一种消极情感,二者的增加意味着零工工作者心理资源的减少[10]㊂伴随着资源的减少,零工工作者将会展现出消极的工作态度和行为㊂基于此,本文认为,认知负荷和情绪耗竭在感知算法控制和工作投入之间起中介作用㊂此外,依据资源保存理论,如果零工工作者能够理解算法系统的运作机制,他们在工作中就能采取措施有效规避算法带来的不利影响,减少资源的消耗㊂反之,如果零工工作者无法理解算法系统的使用过程,他们会产生担忧和焦虑,消耗自身资源[9-11]㊂能够衡量用户理解算法系统运作原因以及运作程度的算法透明度可能会影响感知算法控制引起员工认知和情绪资源消耗的程度[11]㊂因此,本文认为,算法透明度是感知算法控制影响工作投入过程的重要边界条件,探讨算法透明度在感知算法控制和认知负荷㊁情绪耗竭之间的调节作用以及对认知负荷和情绪耗竭中介效果的调节作用是十分必要的㊂综上所述,本文依据资源保存理论,探究零工工作者的感知算法控制对工作投入的影响,厘清认知负荷和情绪耗竭在上述关系中的中介作用以及算法透明度的调节作用,以期丰富算法管理领域的实证研究成果,也为相关组织开展科学的员工管理实践提供参考和借鉴㊂二㊁理论基础与研究假设(一)感知算法控制与工作投入感知算法控制是员工对于算法如何通过规范指导㊁追踪评估和行为约束对其提供在线劳动服务过程进行实时动态控制的综合感知,对员工和组织都会产生重要的影响[12-14]㊂而工作投入作为一种以活力㊁奉献等特质为代表的积极工作状态,是连接个体特征㊁工作因素和工作绩效的纽带[8]㊂资源保存理论为解释感知算法控制对工作投入的影响提供了一个理论视角㊂该理论认为个体有保护和维持自身资源㊁获取新资源的动机㊂当个体的资源出现损耗时,个体会保护自身资源不再减少㊂同时,个体会感到自己受到威胁,进而产生消极的心理体验和工作行为[9]㊂具体而言,感知算法控制表达了零工工作者对于平台制定的标准㊁政策和内容的理解,并基于此形成自己的判断,进而影响他们的行为㊂当零工工作者感知到算法控制时,他们会认为平台在催促他们提高工作效率,并且对自己的行为进行约束㊂为了按照平台的规定按时且高效地完成任务,零工工作者会出现资源损耗等情况㊂此时,他们会减少工作投入以保证不再消耗自身的资源㊂已有研究发现,感知算法控制会给员工带来工作负荷㊁工作不安全感等消极影响[15-16]㊂零工工作者在受到感知算法控制带来的消极影响后,会减少工作投入㊂基于此,本文提出如下假设:H1:零工工作者感知算法控制对工作投入具有显著负向影响㊂(二)认知路径:认知负荷的中介作用认知负荷是指个体在工作过程中,收集㊁分析和处理信息时消耗的认知资源的总和[17]㊂已有研究发现,信息复杂程度[18]和网络环境特征[19]等会影响员工的认知负荷㊂零工工作者使用算法协助自己工作并且感知到算法控制时,他们也会面临复杂的信息以及复杂的网络环境特征,进而增加认知负荷㊂资源保存理论认为,个体由于资源损失而引发的潜在威胁感会影响个体对环境的反应[9]㊂具体而言,当零工工作者感到算法控制时,他们内心中会产生矛盾的认知过程㊂例如,当外卖小哥送餐时间马上要截止时,平台催促外卖小哥要将外卖按时送达,否则就会扣除部分奖励㊂此时,外卖小哥内心中会产生矛盾的过程,即加快配送速度以完成任务或在保证自身安全和遵守交通规则的前提下完成任务㊂这样复杂的心理活动通常会大量消耗零工工作者的认知资源,进一步增强零工工作者的认知负荷[20]㊂因此,本文认为,零工工作者感知算法控制显著正向影响认知负荷㊂进一步地,认知负荷也是工作中重要的压力源之一,会阻碍员工完成工作任务[21]㊂依据资源保存理论,零工工作者在应对压力时,需要投入更多的资源去缓解压力带来的威胁,加快了资源的损耗和流失,这会导致零工工作者减少工作投入[22]㊂Breevaart 和Bakker [23]的研究结论为上述论断提供了实证支持,他们研究发现员工日常的认知负荷会显著负向影响工作投入㊂因此,本文认为,零工工作者认知负荷对工作投入具有显著负向影响㊂基于资源保存理论,个体在资源遭受损失时,会出现的应激反应㊂个体在应对压力的过程中又会投入更多的资源,从而陷入资源损失螺旋[9]㊂综上所述,零工工作者在感知算法控制时需要更多的心智活动以保证任务的完成,这会导致其产生认知负荷㊂认知负荷作为重要的压力源会导致员工心理资源的进一步流失,从而降低工作投入[9,22]㊂Hu 等[24]的研究已经证明了认知负荷在用户熟悉程度和用户满意度之间的中介作用,为上述论断提供了支持㊂因此,本文认为,认知负荷在感知算法控制和工作投入之间起中介作用㊂94㊀第3期㊀张兰霞,李佳敏,毛孟雨:零工工作者感知算法控制对工作投入的影响机制研究基于认知和情感的双路径模型05商㊀业㊀经㊀济㊀与㊀管㊀理2024年基于此,本文提出如下假设:H2:认知负荷在感知算法控制和工作投入之间起中介作用㊂(三)情感路径:情绪耗竭的中介作用情绪耗竭是指个体在处理人际关系㊁使用知识技能的过程中,过度消耗自己的情绪资源而产生焦躁情绪的心理状态[25]㊂零工工作者在感受到算法控制时,会感受到算法对自身的要求和限制,在这种要求和限制下,零工工作者甚至需要立即做出选择[26]㊂基于资源保存理论,零工工作者在选择的过程中可能会感受到角色冲突,产生心理不适,造成情绪资源的损耗,进而导致情绪耗竭[27]㊂因此,本文认为,零工工作者感知算法控制对情绪耗竭具有显著正向影响㊂进一步地,情绪耗竭是工作倦怠的重要表现形式㊂情绪耗竭的员工不仅会对工作失去热情和动力,而且会伴有沮丧㊁焦虑等心理感受[28]㊂员工在情绪耗竭时会出现资源的消耗,在个体情绪资源枯竭的情况下,零工工作者为了防止仅有的资源进一步被消耗,会减少情绪资源投入,进而减少工作投入㊂正如万金等[29]研究发现,员工情绪耗竭显著负向影响工作投入㊂因此,本文认为,零工工作者情绪耗竭对工作投入具有显著负向影响㊂资源保存理论认为,个体在完成任务过程中会损耗自身资源,使个体感受到威胁,进而产生消极的心理体验[9]㊂由于感知算法控制会让零工工作者感到心理不适,导致情绪耗竭㊂情绪资源的流失使零工工作者对工作的活力与热情降低,陷入沮丧和焦虑等消极的情绪中,从而减少了工作投入㊂与上述逻辑推论一致的是,于维娜等[30]验证了情绪耗竭在领导包容性和非工作期间恢复体验之间的中介作用,姚柱和罗瑾琏[31]则验证了情绪耗竭在时间压力和知识隐藏之间的中介作用㊂因此,本文认为,情绪耗竭在感知算法控制和工作投入之间起中介作用㊂基于此,本文提出如下假设:H3:情绪耗竭在感知算法控制和工作投入之间起中介作用㊂(四)认知负荷与情绪耗竭的链式中介作用结合假设H2和H3,基于资源保存理论,当零工工作者感到算法对自身的控制时,会带来紧张和不安,零工工作者的资源会减少[4]㊂此时,零工工作者可能需要频繁切换任务或应对不同类型的工作,这就需要调动大量的认知资源[17]㊂由于感知算法控制涉及对信息的处理和理解,零工工作者可能会感到认知负荷加重㊂高度的认知负荷可能导致零工工作者感到压力和疲劳,这可能引起情绪的负面变化[25]㊂情绪耗竭指的是长时间的心理压力和疲劳,这可能导致个体对工作的情感投入减少[25]㊂因此,当零工工作者产生认知负荷后,自身资源进一步减少,进而表现为情感上的资源耗竭,即情绪耗竭㊂长期的情绪耗竭可能使零工工作者感到疲惫和缺乏动力[28]㊂由于认知资源有限,当个体感到疲劳时,他们可能更难以集中注意力㊁保持高效率和保持对任务的积极投入状态[8]㊂最终,员工为了防止进一步消耗自身资源而减少工作投入㊂因此,本文认为,认知负荷和情绪耗竭在感知算法控制和工作投入之间起链式中介作用㊂基于此,本文提出如下假设:H4:认知负荷和情绪耗竭在感知算法控制和工作投入之间起链式中介作用㊂(五)算法透明度的调节作用算法透明度是指用户可以理解算法系统运作的原因以及如何运作的程度[10]㊂算法的不透明属性和黑箱属性导致许多员工对算法表现出较高的不信任感,还有员工甚至出现了算法厌恶[11]㊂同时,零工工作者在工作中不得不接受算法决策的结果,这会给他们带来不确定感,出现这些感觉也是因为他们不能理解算法运作的机制[32]㊂甚至有研究发现,当组织使用算法管理员工时,如果员工对算法系统有着清晰和准确的理解,员工在工作时会表现出更强的自主感和胜任感[33]㊂因此,算法透明度可能是感知算法控制影响工作投入过程中的一个重要边界条件㊂具体而言,感知算法透明度高的零工工作者会更了解算法背后的原理,更愿意接受算法的监督和提醒,甚至会将算法视为帮助自身提升工作绩效的工作伙伴[34]㊂因此,感知算法透明度高的零工工作者在感受到算法控制时,会认为算法在帮助自己高效地完成工作㊂此时,零工工作者自身的资源会得到补充,感知算法控制对认知负荷和情绪耗竭的正向影响会被削弱[35]㊂反之,感知算法透明度低的零工工作者对算法的运行机制和原理并不了解,只是按照算法分配的工作和提醒完成任务,他们难以处理算法传递给他们的复杂信息,甚至会产生更强的工作不确定性感和工作不安全感[36]㊂因此,感知算法透明度低的零工工作者在感受到算法控制时,会认为算法给他们的工作带来阻碍㊂此时,零工工作者自身的资源会进一步地损耗,感知算法控制对认知负荷和情绪耗竭的正向影响被增强㊂裴嘉良等[37]的研究为上述观点提供了实证支持,他们发现,算法透明度可以调节感知算法控制对自主性动机和控制性动机的影响㊂基于此,本文提出如下假设:H5:算法透明度削弱了感知算法控制与认知负荷(a )和情绪耗竭(b )间的正相关关系,即算法透明度越高,感知算法控制对认知负荷(a )和情绪耗竭(b )的正向影响越弱㊂综上所述,认知负荷和情绪耗竭在感知算法控制影响工作投入的双路径之间均有间接效应㊂因此,本文进一步提出被调节的中介作用假设,即零工工作者感知算法控制通过认知负荷和情绪耗竭影响工作投入的双路径会受到算法透明度的调节㊂当零工工作者感知到的算法透明度高时,认知负荷和情绪耗竭的中介作用就会被削弱㊂具体而言,感知算法透明度低的零工工作者,由于不了解算法背后的原理,在感知算法控制后会感到压力和威胁,因此他们会表现出更高的认知负荷和情绪耗竭㊂而认知负荷和情绪耗竭会导致个体资源的损耗,造成工作投入的减少㊂基于此,本文提出如下假设:H6:算法透明度削弱了认知负荷(a )和情绪耗竭(b )的间接效应,即算法透明度越高,认知负荷(a )和情绪耗竭(b )在感知算法控制和工作投入之间的间接作用越弱㊂综上所述,本文的理论模型如图1所示㊂图1㊀研究模型图三㊁研究方法(一)样本和程序本文采用问卷调查法收集数据,样本来自山东省济南市平台企业中的零工工作者,具体包括外卖配送员㊁网约车司机㊁跑腿人员和在线家政服务人员㊂研究人员首先将设计好的问卷导入问卷收集平台问卷星中,生成问卷电子链接和二维码;随后联系相关企业的负责人协助发放问卷电子链接和二维码㊂研究人员依靠校友关系,首先联系了9家使用算法管理的平台企业㊂在与相关企业负责人沟通后,最终有7家平台企业同意协助发放调查问卷电子链接和二维码㊂问卷的填写均为匿名,并且完全尊重员工的个人意愿㊂由于本文中的所有变量均为员工自我评价,为降低共同方法偏差对数据的不利影响,本文采用两阶段问卷收集法㊂为保证问卷数据的准确匹配,要求被试填写手机号后6位㊂虽然相关企业的员工使用算法工作,但为确保问卷的准确性,避免问卷链接和二维码被发送到不相关的被试手中,研究人员在问卷中设置了甄别题项,即向被试确认在工作中是否使用算法㊂如果被试选择否 ,则问卷会自动结束㊂第一轮调研在202315㊀第3期㊀张兰霞,李佳敏,毛孟雨:零工工作者感知算法控制对工作投入的影响机制研究基于认知和情感的双路径模型25商㊀业㊀经㊀济㊀与㊀管㊀理2024年年1月进行,测量了感知算法控制㊁算法透明度和人口统计学变量等信息㊂本轮共发放465份问卷,收回445份问卷㊂在删除作答时间过短㊁作答结果具有明显规律等不合格问卷后,共得到431份有效问卷,问卷有效回收率为92.69%㊂第二轮调研于两个月后进行,测量了认知负荷㊁情绪耗竭和工作投入㊂本轮主要对第一轮中的有效问卷进行追踪,通过对被试手机号后6位进行匹配,共收回415份问卷,在删除作答时间过短㊁作答结果具有明显规律等不合格问卷后,共得到397份有效问卷,问卷有效回收率为92.11%㊂在有效样本中,男性占52.39%,女性占47.61%;18 25岁占33.21%,26 30岁占25.14%,31 40岁占35.21%,41岁以上占6.44%;工作2年以下占比33.21%,3 5年占比29.31%,6 8年占比25.73%,9年及以上占比11.75%;大学本科学历的样本最多,占样本总数的66.75%,初中及以下学历的样本最少,占样本总数的8.81%㊂(二)变量测量本文中的变量均选取国内外成熟量表进行测量,对国外量表严格按照翻译回译的程序设计问卷[38]㊂为保证翻译后的国外量表在中国情境下的适用性,邀请了两位组织行为领域的博士研究生以及一位零工工作者对量表的内容进行了审查㊂所有问卷均采用5级Likert量表进行测量,其中,1代表完全不同意 ,5代表完全同意㊂1.感知算法控制㊂选取裴嘉良等[4]开发的包括11个题项的量表测量感知算法控制㊂其中,代表性题项为算法按照平台标准对我的工作做出了规范指示 ,该变量的内部一致性系数是0.88㊂2.算法透明度㊂本文借鉴裴嘉良等[37]学者的做法,在Durcikova和Gray[39]开发的3题项透明度量表的基础上对测量题项进行改编㊂其中,代表性题项为我可以随时查询有关平台算法运作的信息 ,该变量的内部一致性系数是0.85㊂3.认知负荷㊂采用Mohr等[40]开发的3题项量表来测量认知负荷㊂其中,代表性题项为我觉得下班后休息很不容易 ,该变量的内部一致性系数是0.80㊂4.情绪耗竭㊂采用Boswell等[41]开发的3题项量表测量情绪耗竭㊂其中,代表性题项为我觉得工作使我精神枯竭 ,该变量的内部一致性系数是0.81㊂5.工作投入㊂采用Schaufeli等[42]学者开发的9题项量表测量工作投入㊂其中,代表性题项为我在工作时会达到忘我的状态 ,该变量的内部一致性系数是0.90㊂6.控制变量㊂参考以往研究[43],本文将年龄㊁性别㊁受教育程度和工作年限等人口统计学变量作为控制变量㊂其中,年龄和工作年限为填空题,由被试直接填写其年龄和工作年限;性别和受教育程度为选择题,由被试根据自己实际情况选择㊂四㊁数据分析及结果(一)共同方法偏差检验使用Harman单因子检验方法对共同方法偏差进行检验[44]㊂将所有变量的题项未旋转进行探索性因子分析,结果表明,第一个主成分的特征值大于1,且解释了30.47%的变异值,没有超过40%的临界值,说明本文的共同方法偏差问题并不严重㊂同时,鉴于Harman单因子检验方法结果可能不灵敏,故本文在五因子模型的基础上,加入误差变量因子㊂随后,将该模型与五因子模型进行比较,发现各指标的变化不大(ΔCFI=0.011,ΔTLI=0.012,ΔRMSEA=0.010),这再次说明本文的共同方法偏差问题并不严重[45]㊂(二)描述性统计分析本文所涉及变量的均值㊁标准差和各变量间的相关系数如表1所示㊂由表1可知,感知算法控制与情绪耗竭(r=0.33,p<0.01)和认知负荷(r=0.32,p<0.01)显著正相关,与工作投入(r=-0.30,p<0.01)显著负相关;情绪耗竭与工作投入(r=-0.29,p<0.01)显著负相关;认知负荷与工作投入(r=-0.33,p< 0.01)显著负相关㊂因此,H1得到初步支持㊂同时,各变量AVE的平方根均大于该变量与其他变量的相关。

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反常霍尔效应理论的研究进展_梁拥成

前沿进展反常霍尔效应理论的研究进展3梁拥成1,3 张　英2 郭万林1 姚裕贵3, 方　忠3,(1　南京航空航天大学纳米科学研究所　南京　210016)(2　北京师范大学物理系　北京　100875)(3　中国科学院物理研究所　北京凝聚态物理国家实验室　北京　100080)摘　要文章介绍了在铁磁性材料中反常霍尔效应的发现及其机制研究的历史;阐述了反常霍尔效应理论研究最近取得的重大进展,即倒空间中布洛赫态的贝里曲率(规范场)特性决定了霍尔电导率;同时指出,建立系统地解释反常霍尔效应机制的理论仍然是一个挑战性的任务.关键词反常霍尔效应,第一性原理计算,铁磁性,自旋-轨道耦合,贝里曲率Progress of studi es on the ano ma lous Ha ll effectL I A NG Yong 2Cheng1,3 ZHANG Ying 2 G UO W an 2L in 1 Y AO Yu 2Gui 3, F ANG Zhong3,(1　Institute of N ano Science,N anjing U niversity of Aeronautics and Astronautics,N anjing 210016,China )(2　D epart m ent of Physics,B eijing N or m al U niversity,B eijing 100875,China )(3　B eijing N ational L aboratory for Condensed M atter Physics,Institute of Physics,Chinese A cade m y of Sciences,B eijing 100080,China )Abstract The phenomenon,discovery and hist ory of the anomalous Hall effect are reviewed .Studies on its mechanis m are discussed with emphasis on recent p r ogress,i .e .,the relati onship bet ween the ano mal ous Hall conductivity and the Berry curvature (gauge field )of the B loch states in momentum s pace .It is pointed out that a full understanding of the anomal ous Hall effect is still a challenging p r oblem.Keywords ano malous Hall effect,first -p rincip les calculations,ferr omagnetis m,s p in 2orbit coup ling,Berry curvatures .3　国家自然科学基金(批准号:90303022,10334090,10425418,60576050,10404035,10534030,10674163,10372044,50275073)、国家重点基础研究发展计划(批准号:2005CB724400)、中科院知识创新工程、教育部创新团队和科技创新工程重大项目培育基金(批准号:705021)资助项目2007-01-17收到　通讯联系人.Email:ygyao@aphy .i phy .ac .cn 通讯联系人.E mail:zfang@aphy .i phy .ac .cn;1　反常霍尔效应如图1(a )所示,一个非磁性的金属或半导体薄片放置在xy 平面内,外加电场E 沿x 方向,外加磁场B 垂直于薄片平面而沿z 方向.这时材料中的载流子不仅受到来自于外加电场的力而沿x 方向运动,同时还受到磁场的洛伦兹力的作用而在y 方向产生附加的横向运动.这横向运动将造成薄片两侧电荷积累,从而沿y 方向产生一横向霍尔电压V H .横向霍尔电阻率ρxy 的大小依赖于外加磁场的大小,即ρxy =R 0B ,(1)其中R 0称为常规霍尔系数,它的大小与载流子数目成反比,符号取决于载流子的类型.这种现象称为常规霍尔效应(ordinary Hall effect ).然而在如图1(b )所示的铁磁性(F M )的金属材料样品里,横向电阻率ρxy 的大小除了包括(1)式中的常规项外,还另外增加了与样品的磁化强度M 大小有关的反常项,当样品达到饱和磁化强度M s 时,它就变成了常数.图2给出了横向霍尔电阻率ρxy 与磁场大小B 的关系曲线:ρxy 先随B 迅速线性增加,经过一个拐点后线性缓慢增加,直至饱和.显然,这不能简单用磁场的洛伦兹力来解释.因而,通常人们称这种现象为反常霍尔效应(anomal ous Hall effect ).由于它与自发磁化有关,也称为自发霍尔效应(s pontaneous Hall effect ).根据经验,ρxy =R 0B +4πR s M ,(2)其中R s 称为反常霍尔系数,通常它大于常规霍尔系数R 0至少一个量级以上,且强烈地依赖于温度.另外,在铁磁性金属中,即使没有外加磁场B ,仅有x 方向的电场E 时,也会出现横向霍尔电压V H .实际上,为了让此现象明显,常用一弱的磁场B 使样品内的磁畴都平行取向.图1　(a )常规霍尔效应示意图;(b )反常霍尔效应示意图常规霍尔效应有着广泛的应用,如确定半导体的导电类型,测定载流子浓度和迁移率,以及制造霍尔传感器等等[1],而反常霍尔效应则是探究和表征铁磁材料中巡游电子输运特性的重要手段和工具之一.它的测量技术被广泛应用于许多领域,最重要的应用是在新兴的自旋电子学方面.例如,在III -V 族半导体中掺入磁性锰原子,从而实现材料铁磁性与半导体性的人工联姻,促进了稀磁半导体(DMS )材料的诞生,稀磁半导体材料最初就是通过图2　霍尔电阻率ρxy 与磁场大小的关系曲线示意图在低温和高温范围内测量样品的反常霍尔效应发现的[2,3],而且反常霍尔效应在稀磁半导体材料整个应用过程中的性能表征都有着不可替代的作用.2　反常霍尔效应理论机制的研究历史尽管反常霍尔效应有着至关重要的作用而且这种现象的发现已有一百多年历史,但关于理论机制一直处于争论之中.到目前为止,还没有建立完整的理论体系对有关实验结果做出非常合理的、定量的解释.争论的焦点是该效应是内禀机制还是外在机制,以及如何处理杂质、缺陷和声子等散射问题.1879年,Ed win Hall 在实验中观测到常规霍尔效应.在紧接着的两年内,他测量铁、钴、镍等铁磁性材料时[4—6]发现了三个新的特点:(1)霍尔系数比早期测量过的金和铜的霍尔系数大10倍;(2)随着温度升高,霍尔系数迅速增大;(3)霍尔电压与外加磁场不再有线性关系,而且,当磁化强度达到饱和时,它就变成常数.这三个特点实际上标志着反常霍尔效应的首次发现.为了证实和解释霍尔发现的这种现象,在接下来的将近80年的时间内,许多研究者在这方面做了大量的实验研究工作.例如,Kundt [7]发现霍尔电阻近似与磁化强度成线性关系;S m ith 和Sears [8]于1929年提出上面列出的霍尔电阻与磁化强度的经验关系式(2).然而在对反常霍尔效应机制的理论解释方面基本没有大的进展.直到1954年,Kar p lus 和Luttinger [9,10]才从理论上详细研究了自旋-轨道耦合作用对自旋极化巡游电子的输运影响,第一次提出了反常霍尔效应的内禀机制.他们完全忽略杂质、声子等散射,把外加电场作为微扰动展开,推导出在包含自旋-轨道耦合相互作用的理想晶体能带中运动的载流子,存前沿进展在一个正比于贝里曲率的反常速度,它的具体形式我们将在下面给出.正是由于这个反常速度的存在,在外加电场下,同时考虑到上自旋与下自旋的电子占据数不相等,导致电子将会有个净的横向电流,产生反常霍尔效应[11].也就是说,反常霍尔效应是自旋-轨道耦合的必然结果,仅和材料的固有能带结构相关,是材料的内禀特性,和散射无关.按照这个理论,反常霍尔系数R s 与总电阻的平方ρ2成正比.这与当时几种过渡金属的实验观测结果是一致的,如铁就是典型的一个例子.然而,这个结论很快受到S m it [12]的质疑,他批驳了Kar p lus 和Luttinger 的观点,认为在真实的材料中总是存在缺陷或者杂质,电子的运动将会受到散射,结果对于理想周期性晶格,内禀的反常霍尔系数R s 将会消失为零.进一步,他提出了螺旋散射(ske w scattering )机制,认为对于固定自旋方向的电子,由于自旋-轨道耦合相互作用,电子受到杂质的散射是不对称的,结果定向运动的电子偏离原来的方向,形成横向的电荷积累,它的直观物理图像如图3(a )所示.螺旋散射主要由被散射的载流子偏离原来路径方向的角度θH (也称为自发霍尔角)[6]来表征:θH =ρxy /ρ.(3)因此,根据螺旋散射可以得到霍尔电阻率ρxy 与ρ成正比,即ρxy ∝ρ,(4)而且霍尔电阻率ρxy 还依赖于散射势的类型和作用距离.图3　(a )反常霍尔效应螺旋散射(ske w scattering )机制示意图;(b )反常霍尔效应边跳(side 2jump )机制示意图Kohn 和Luttinger[13]为了修正没有考虑散射的局限性,他们重新把密度矩阵对自旋-轨道耦合和杂质散射势的强度一起进行微扰展开,结果在新得到的霍尔电导率的表达式中,除了原来的Kar p lus 和Luttinger 结果[9]外,还增加了一项杂质散射作用的贡献.后来,Luttinger [14]进一步运用这种方法具体研究了没有关联作用的弱杂质散射势模型,基本发现有相同的结果,然而,在他的电导率表达式里,对霍尔电导率贡献的散射项不依赖于散射势,而仅仅取决于体系的电子结构,这点是奇怪的,但他没有给出具体的解释.最后他回应了S m it 的质疑,他指出,在理想周期晶格结构里反常霍尔系数R s 并没有出现抵消情况.在接下来的十年内,以Luttinger 和S m it 为代表的两种观点一直争论着,始终没有得到调和.然而在1970年,Berger [15]又提出反常霍尔效应的边跳(side 2ju mp )机制,使人们对反常霍尔效应的量子力学的起源更加迷惑.边跳散射机制模型如图3(b )所示.当自旋-轨道相互作用存在时,由于自旋-轨道作用取决于自旋角动量s 和轨道角动量L 的矢量积,与二者之间的夹角有关,于是散射后对于固定自旋方向的电子运动轨迹将有一个横向跳跃Δy ,这不断的横向跳跃也相当于使载流子获得一横向平均速度,导致横向电荷积累和霍尔电压的产生.按照这种模型,载流子波包的横向跳跃距离Δy 与螺旋散射参数θH 和平均自由程λ有关:tan θH ≈θH ≈Δy /λ≈ρΔy .(5)因此,根据边跳机制可以得到霍尔电阻率ρxy 与ρ成二次方关系,即ρxy ∝ρ2.(6)这似乎可以成功地解释在铁、镍和铁镍合金中实验观察到的ρxy 与总电阻平方ρ2成线性关系的现象.边跳机制模型与具体散射势的形式无关.螺旋散射和边跳散射机制都属于外在机制,都是由于杂质或声子散射造成的,在Berger 与S m it 进一步交换各自观点后[16—19],似乎认为反常霍尔效应是由杂质散射引起的外在机制造成的,而Luttinger 最早提出的内禀机制却渐渐失去了原有的主导地位.然而,考虑到在实际材料中,人们很难对杂质的散射势建立准确定量的模型,外在机制预测的结果很难与实验定量地比较,因此主要由外在机制导致反常霍尔效应这个结论是值得怀疑的.3　反常霍尔效应理论的最新进展近来,由于自旋电子学的兴起,人们需要理解和探究稀磁半导体材料的性质,反常霍尔效应是探测和确定给定温度下材料体系铁磁态最基本的表征工具之一,这就迫使人们对反常霍尔效应理论机制进前沿进展行深入的思索.与自旋-轨道耦合引起杂质不对称散射的外在机制不同,近来最新研究工作的进展[20—24]主要是从贝里相角度出发重新审视最早由Luttinger 提出的内禀机制,并认为在很多情形下反常霍尔效应主要是由内禀机制引起的,即动量空间布洛赫波函数的贝里曲率决定了霍尔电导率.下面我们简单地综述反常霍尔效应内禀机制的基本理论[25—32].在理想晶体中,按照布洛赫波定理,波函数为│ψn (k ,r )〉=e i k ·r │u n (k ,r )〉,(7)其中n 是能带指标,k 是波矢,r 是实空间坐标,│u n (k ,r )是晶格周期函数.晶体中载流子在外加电磁场中的准经典运动可以用布洛赫波函数组成的波包来描述,它满足下面运动方程[28,29]:r ·=1 9εn 9k-k ·×Ωn (8)k ·=-e(E +r ·×B ),(9)其中Ωn 为贝里曲率,它的定义为Ωn =-I m 〈 k u n │×│ k u n 〉.(10)在运动方程(8)式中,第二项就是前面提到的反常速度,它与外磁场B 无关,方向垂直于外电场E .正是这个反常速度给出横向电导率(霍尔电导率)的内禀根源.利用玻尔兹曼输运理论,积分整个布里渊区(BZ )内所有占据能带的贝里曲率,就能给出晶体的霍尔电导率σxy =-e2∫B Zd 3k (2π)3Ωz(k ),(11)其中Ωz(k )为所有占据能带的贝里曲率之和,即Ωz (k )=∑nf n Ωzn (k ).(12)(10)式定义的贝里曲率与贝里相位的关系为βn =∮C d k ·〈u k │99k│u k 〉=∮C d k ·A n =∫∫sd S ·Ωn .(13)形式上,A n 可看作k 空间中的“矢势”,而Ωn 则看成相应的“磁场强度”,βn 则代表通过以闭曲线C 为边界的曲面S 的“磁通量”,因而贝里曲率就是规范场.在电子能带简并或近简并时,这个规范场将会极大的增加,形成尖锐的峰,这点相应于贝里相联结定义的规范场的源.能带简并或接近简并点能充当动量空间里磁单极的作用,结果反常霍尔效应也可看作动量空间里磁单极的手印和表象[25,32].图4就是铁磁Sr Ru O 3材料的t 2g 能带实际计算出的规范场在动量空间k z =0平面上的实际分布:在k x =k y =0处形成尖锐的峰,而沿k x =±k y 方向形成陡峭的脊.而图5给出了常见的铁磁材料铁在布里渊区(010)面内贝里曲率Ωz (k )大小的实际分布图,也形成尖锐的峰与脊.因而,动量空间内规范场的特性决定了霍尔电导率的特性,也就是反常霍尔效应是由磁性材料能带所决定的,是材料的内禀特性.图4　Sr RuO 3的t 2g 能带实际计算出的规范场在动量空间k z =0的ΓM平面内的实际分布图(见文献[25])图5　铁磁材料Fe 在布里渊区(010)ΓM 平面内贝里曲率Ωz(k )的大小分布图(见文献[32])对于这个理论结果((11)式),Jung wirth等[24,31]首先把这个理论运用到能用四价带或六价带的Luttinger 有效哈密顿量描述的第Ⅲ-Ⅴ族半导体掺锰的稀磁材料,成功地得到与(Ga,Mn )A s 和(I n,Mn )A s 实验结果定量一致的数据.紧接着在随后的研究中,最大的进展是结合第一性原理计算来定量地研究真实铁磁材料的反常霍尔效应,并成功地用于解释一些相关实验.表1提供了几种典型的铁磁材料Fe [32,33],Co,N i,Mn 5Ge 3[34]和Sr RuO 3[25,26]中反常霍尔电导率的第一性原理计算值与实验前沿进展值[12,35,36]比较,计算结果都很好地符合实验结果.此外对于CuCr2Se4-x B r x体系中,掺杂对反常霍尔效应的系统影响也获得了实验与理论的一致的结果[37,38].所有这些理论计算的成功都强有力地表明了反常霍尔效应内禀机制的存在,这和过去外在机制在反常霍尔效应中占主导地位的观点相矛盾,这促使人们重新思考反常霍尔效应的起源问题.表1　铁磁材料Fe,Co,N i,Mn5Ge3和Sr RuO3中反常霍尔电导率的计算值与实验值的比较,单位为(Ω·c m)-1材料理论值实验值Fe(bcc)7501030[35]Co(hcp)492500[36]N i(fcc)-2073-753[12]Mn5Ge3964310[34]860[34] Sr RuO3-60-100[25] 为了解决内外机制的争论,人们需要建立一个可同时处理内外机制的普适理论[39,40].考虑到实际材料里,杂质和缺陷等无序总是存在的,显然这个理论必须有处理由这些无序引起的散射问题的能力.然而系统解释所有的实验结果的理论(特别是结合第一性原理计算的理论)到目前远没有建立,还有很多困惑需要解决.例如,对于Sr Ru O3[25,26,41],虽然输运、光、磁等实验结果被第一性原理计算所重现,但是发现霍尔电阻率ρxy与温度并非单调变化,甚至还有符号的改变,这完全违背上面的经验公式(2).因此,反常霍尔效应机制的研究还有待于取得进一步突破,完善的理论(特别是结合第一性原理计算的理论)的建立在目前还是一个具有挑战性的任务.除了反常霍尔效应以外,自旋霍尔效应的产生也具有相似的机理.由于在自旋-轨道耦合的作用下贝里相的存在,外加电场下就会诱导横向的自旋流动即内禀自旋霍尔效应.这种效应自从最近理论上[42,43]和实验上[44,45]提出以后,已经极大地引起了人们的注意.然而尽管这些关于自旋霍尔效应的研究取得了很大突破和进展,但还还存在着许多争论,例如自旋流的定义问题等等[46].考虑到产生自旋霍尔效应与反常霍尔效应的机制原理是类似的[47,48],对反常霍尔效应的研究将有助于理解自旋霍尔效应.4　结束语由于新的稀磁半导体材料和自旋电子学材料的兴起,为了更好地表征这些铁磁材料的内禀性质,需要人们更深入地理解反常霍尔效应的机制,这吸引了很多理论工作者的兴趣,特别是在最近几年,反常霍尔效应的内禀机制的研究取得了重大进展.然而,结合第一性原理计算方法,建立一套系统的理论体系来令人信服地解释螺旋散射、边跳等外在机制与内禀机制的所有争论,还需要进一步的研究,这仍然是一个具有挑战性的任务.这些对于机制类似的自旋霍尔效应的研究也是一样的.参考文献[1]杨锡震,杨道生,田强.物理实验,2005,25(10):3[YangX Z,Yang D S,Tian Q.physical Experi m ent,2005,25(10):3(in Chinese)][2]Ohno 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al.Phys.Rev.Lett.,2006,97:046604[40]Onoda S,Sugi m ot o N,Nagaosa N.Phys.Rev.Lett.,2006,97:126602[41]Mathieu R,A sa m itsu A,Ya mada H et al.Phys.Rev.Lett.,2004,93:016602[42]Muraka m i S,Nagaosa N,Zhang S C.Science,2003,301:1348[43]Sinova J et al.Phys.Rev.Lett.,2004,92:126603[44]W underlich J,Kaestner B,Sinova J et al.Phys.Rev.Lett.,2005,94:047204[45]Kat o Y K,Myers R C,Gossard A C et al.Science,2004,306:1910[46]Shi J R,Zhang P,Xiao D et al.Phys.Rev.Lett.,2006,96:076640[47]Yao Y,Fang Z.Phys.Rev.Lett.,2005,95:156601[48]Guo G Y,Yao Y G,N iu Q.Phys.Rev.Lett.,2005,94:226601·物理新闻和动态·自旋光子开关许多研究者试图开发一种自旋电子学“s p intr onic”装置,利用电子的自旋以及电荷来存储和处理信息.而另一些人则想利用光线与金属表面的电子的集体振荡之间的相互作用来产生一种称作“p las monic”(纳米光子学的一个分支)的装置来处理和传输数据.A lberta大学的Abdul Elezabbi等发明了一种材料,将自旋电子学与p las monic相结合,作为频率为太赫兹的光线的开关.当这种材料置于外磁场中时,在微米大小的钴颗粒中的电子发生自旋极化.钴颗粒的部分表面覆盖有金层,如果频率在太赫兹范围的光线照射在这种材料上,与光线相关联的磁场将一些自旋极化的电子从钴中驱赶到金层中.这导致金和钴之间产生一种各向异性磁致电阻.当磁场去掉之后,不再有各向异性磁致电阻,大部分光线经由p las mon从材料中传输出来.而加上磁场后,由于各向异性磁致电阻的产生使电阻增加,阻止p las mon的流动,在一些样品中,光线的传输降低70%以上.有关论文发表在Phys.Rev.Lett.,2007,98:133901(树华　编译自PhysicsW eb Ne ws9Ap ril2007)美国物理年会热议固态氦超流美国物理学会年会于2007年3月5—9日在科罗拉多州首府丹佛召开.期间固态氦超流再次成为热门话题.2004年,M.Chen和E.Ki m构建了一个固态氦扭摆(小罐中的氦始终保持加压状态).他们发现,当温度降到几十mK,小罐的扭动频率突然增加.这意味着小罐整体的转动惯量突降,罐中的部分固态氦不再参与摆动,而是脱离了主体,并且可以无阻地在主体固态氦之间穿插(见Science,1July2005,p38).这一现象,当时被认为是固态氦超流.不过,一些理论物理学家很快就论证了:上述穿插图像在有序晶体中是完全不可能的.替代的解释是:残存在固态氦中的传统超流液氦以逾渗方式无阻地穿越固态氦晶体中的缺陷(《固态氦也能超流吗?》一文刊登在《物理》,2004,33(6):468).后一种解释也得到了实验的支持:Reppy和R ittner在类似的扭摆实验中,对固态氦晶体施行稍稍加热,以“退火”消除固态氦晶体中的缺陷.他们发现,流动受阻(见Science,24March2007,p1693).现在,所有的实验小组(包括M.Chen以及来自日本横滨的Keiya Shiraha ma等)都已重复了Reppy等的结果.此外,实验还证实,如果令液氦急速凝固,致使固态氦中包含大量的晶粒边界和缺陷,在“氦雪球”中自由流动的氦原子,可以高达20%.有理论物理学家通过计算模拟确认,氦原子的确可以沿着晶粒边界无阻地滑移.但有实验者指出,这不足以解释高达20%的原子流量.总之,这其中包含着很新的物理问题.(戴闻　编译自Science,6Ap ril2007,p.46)前沿进展。

Probing New Higgs-Top Interactions at the Tree-Level in a Future e^+e^- Collider

a rXiv:h ep-ph/971355v114Oct1997UCRHEP-T206October 1997Probing New Higgs-Top Interactions at the Tree-Level in a Future e +e −Collider 1Shaouly Bar-Shalom Department of Physics,University of California,Riverside CA 92521,USA.Abstract The possibility of observing large signatures of new CP-violating and ﬂavor-changing Higgs-Top couplings in a future e +e −collider experi-ments such as e +e −→t ¯t h,t ¯t Z and e +e −→t ¯c νe ¯νe ,t ¯c e +e −is discussed.Such,beyond the Standard Model,couplings can occur already at the tree-level within a class of Two Higgs Doublets Models.Therefore,an extremely interesting feature of those reactions is that the CP-violatingand ﬂavor-changing eﬀects are governed by tree-level dynamics.These reactions may therefore serve as unique avenues for searching for new phenomena associated with Two Higgs Doublets Models and,as is shown here,could yield statistically signiﬁcant signals of new physics.We ﬁnd that the CP-asymmetries in e +e −→t ¯t h,t ¯t Z can reach tensof percents,and the ﬂavor changing cross-section of e +e −→t ¯c νe ¯νe is typically a few fb’s,for light Higgs mass around the electroweak scale.2.Introductory Remarks And Two Higgs Doublets ModelsA future high energy e+e−collider running at c.m.energies of0.5–2TeV,oftenreferred to as the Next Linear Collider(NLC),is designed,in part,to study indetail the nature of the scalar potential[1].It may be also very useful for a closeexamination of the top quark Yukawa couplings to scalar particle(s)which,in turn,may give us a clue about the properties of the scalar particle(s).In a NLC with a yearly integrated luminosity of the order of100fb−1,a detailedstudy of cross-sections at the level of∼few fb’s may become feasible.In particular,for top-Higgs systems,the NLC will enable a detailed examination of new phe-nomena,beyond the Standard Model(SM),associated with new CP-violating andﬂavor-changing(FC)top Yukawa couplings to scalar particle(s),such as the onesdiscussed here.Indeed,the top quark,being so heavy,m t∼175GeV,is the most sensitive to these new interactions.In the SM,the scalar potential is economically composed of only one scalardoublet.Even a mild extension of the SM with an additional scalar doublet[2],can give rise to rich new phenomena beyond the SM associated with top-Higgssystems,e.g.,tree-level CP-violation[3,4,5]and tree-levelﬂavor-changing-scalar(FCS)transitions[6,7,8],in interaction of neutral scalars with the top quark.Here we present three distinct reactions which are very powerful probes of thetth and t¯c h Yukawa couplings.Theﬁrst two reactions,e+e−→t¯t h and e+e−→t¯t Z [3,4],exhibit large CP-violating asymmetries,at the order of tens of percent,already at tree-level.The third is tree-level t¯c production through the W+W−fusion process, e+e−→W+W−νe¯νe→t¯cνe¯νe[6],which appears to be extremely sensitive to a t¯c h FCS interaction.In the presence of two Higgs doublets the most general Yukawa lagrangian canbe written as:L Y=U1ij¯q i,L˜φ1u j,R+D1ij¯q i,Lφ1d j,R+U2ij¯q i,L˜φ2u j,R+D2ij¯q i,Lφ2d j,R+h.c.,(1) whereφi for i=1,2are the two scalar doublets and U k ij,D k ij,for k=1,2,are the Yukawa couplings matrices which are in general non-diagonal.Depending onthe assumptions made,one can then obtain diﬀerent versions of a Two Higgs Dou-blet Model(2HDM).In particular,if one imposes the discrete symmetriesφ1;φ2→−φ1;φ2and d i,R;u i,R→−d i,R;−u i,R or−d i,R;u i,R one arrives at the so called Model I or Model II,respectively,depending on whether the-1/3and2/3charged quarks are coupled to the same or to diﬀerent scalar doublets.If,in addition,these discrete symmetries are softly violated by a mass-dimension-two term in the Higgs potential,then the real and imaginary parts of the Higgs doublets mix,giving rise to CP-violating scalar-pseudoscalar mixed couplings of a neutral Higgs to fermions already at the tree-level[9].On the other hand,if one does not impose the above dis-crete symmetries,one arrives at a most general version of the2HDM,often called Model III,in which both FCS transitions and CP-nonconserving interactions be-tween the neutral Higgs particles and fermions are present at tree-level(for a recent short review see e.g.,[10]).The scalar spectrum of any of the above2HDM’s con-sists of three neutral Higgs and two charged Higgs particles which are not relevant for the present discussion.For reasons discussed in the following sections,for both the CP-violating eﬀects in e+e−→t¯t h,t¯t Z and the FC eﬀects in e+e−→t¯cνe¯νe, only two out of the three neutral Higgs of the2HDM’s(i.e.,Models II and III)are relevant.We denote these two neutral Higgs particles by h and H corresponding to the lighter and heavier Higgs-boson,respectively.In some instances we denote a neutral Higgs by H,then H=h or H is to be understood.The H t¯t interaction lagrangian piece of a general2HDM can be written as:L H tt=−g W2m tsinβ;R12tanβ;R322,b ht=0 and there is no phase in the ht¯t interaction lagrangian.In Model III with the Cheng-Sher Ansatz(CSA)[11],the couplings of the neutral=g W √scalars to fermions are given byξU,Dij√m t m c2Existing experimental information does not provide any useful constraints onλtc;in particular, we may well haveλtc∼O(1)[10].(c)(a)e h , HZ Z Zte(b)(a)γ,Z tt t e e Figure 1:Tree-level Feynman diagrams contributing to e +e −→t ¯t h (left hand side)and e +e −→t ¯t Z (right hand side)in the unitary gauge,in a two Higgsdoubletmodel.For e +e −→t ¯t Z ,Diagram (a )on the right hand side represents 8diagramsin which either Z or γare exchanged in the s-channel and the outgoing Z isemittedfrom e +,e −,t or ¯t .3.e +e −→t ¯t h,t ¯t Z ;Cases of Tree-Level CP-Violation 3The reactions:e +(p +)+e −(p −)→t (p t )+¯t (p ¯t )+h (p h ),(9)e +(p +)+e −(p −)→t (p t )+¯t (p ¯t )+Z (p Z ),(10)exhibits large CP violation asymmetries in a 2HDM.A novel feature of these re-actions is that the eﬀect arises at tree graph level.Basically,for the tth (ttZ )ﬁnal states,Higgs(Z )emission oﬀthe t ,¯t interferes with the Higgs(Z )emission oﬀthe s-channel Z -boson (see Fig.1)[3,4].We ﬁnd that the processes e +e −→t ¯t h and e +e −→t ¯t Z provide two independent,but analogous,promising venues to search for signatures of the same CP-odd phase,residing in the top-neutral Higgs coupling,if the value of tan β(the ratio between the two VEV’s in a 2HDM)is in the vicinity of 1.In particular,they serve as good examples for large CP-violating eﬀects that could emanate from t systems due to the large mass of the top quark and,thus,they might unveil the role of a neutral Higgs particle in CP-violation.Although these reactions are not meant(necessarily)to lead to the discovery of a neutral Higgs,they will,no doubt,be scrutinized in the NLC since they stand out as very interesting channels by themselves.In particular,they could perhaps providea unique opportunity to observe the top-Higgs Yukawa couplings directly[12,13,14].In[12,13],using a very interesting generalization of the optimal observables technique used here,Gunion et al.have extended our work on CP-violation in e+e−→t¯t h described below,to include a detailed cross-section analysis such that all Higgs Yukawa couplings combinations are extracted.A detailed cross-section analysis of the reaction e+e−→t¯t Z was performed in the SM by Hagiwara et al.[14].There,it was found that the Higgs exchange contribution of diagram(b)on the right hand side of Fig.1will be almost invisible in a TeV e+e−collider for neutral Higgs masses in the range m h<2m t.On the contrary,we will show here that if the scalar sector is doubled,then the lightest neutral Higgs may reveal itself through CP-violating interactions with the top quark even if m h<2m t.In the unitary gauge the reactions in Eqs.9and10can proceed via the Feynman diagrams depicted in Fig.1.We see that for e+e−→t¯t Z,diagram(b)on the right hand side of Fig.1,in which Z and H are produced(H=h or H is either a real or virtual particle,i.e.m H>2m t or m H<2m t,respectively)followed by H→t¯t,is the only place where new CP-nonconserving dynamics from the Higgs sector can arise,being proportional to the CP-odd phase in the H t¯t vertex.As mentioned above,in both the tth and the ttZﬁnal state cases,CP-violation arises due to interference of the diagrams where the Higgs is coupled to a Z-boson with the diagrams where the Higgs or Z is radiated oﬀthe t or¯t.We note that in the ttZ case there is no CP-violating contribution coming from the interference between the diagrams with the ZZ H coupling and the diagrams where the Z-boson is emitted from the incoming electron or positron lines.The relevant pieces of the interaction Lagrangian involve the H t¯t and the H ZZ couplings and is given in Eqs.2and6,respectively.As usual the couplings a h,H,t and c h,H in Eqs.3and7,respectively,are functions of tanβ≡v2/v1(the ratio b h,Htof the two VEVs)and of the three mixing anglesα1,α2,α3which characterize the Higgs mass matrix.As was mentioned in the previous section,only two(denotedhere by h and H)out of the three neutral Higgs are relevant for the CP-violatingeﬀect studied here.The reason is that only two out of the three neutral Higgsparticles in the theory can simultaneously have a coupling to vector bosons and apseudoscalar coupling to fermions.We have denoted their couplings by a h t,b h t,c h anda H t,b H t,c H,corresponding to the light,h,and heavy,H,neutral Higgs,respectively.This implies the existence of a“GIM-like”cancellation,namely,when both h andH contribute to CP-violation,then all CP-nonconserving eﬀects,being proportionalto b h t c h+b H t c H,must vanish when the two Higgs states h and H are degenerate.Inthe following we set the mass of the heavy Higgs,H,to be m H=750GeV or1TeV.In the process e+e−→t¯t h,a Higgs particle is produced in theﬁnal state,there-fore,the heavy Higgs-boson,H,is not important and this“GIM-like”mechanismis irrelevant.Note that there is an additional diagram contributing to e+e−→t¯t h, which involve the ZhH coupling and is not shown in Fig.1.This diagram is, however,negligible for the large m H values used here.In contrast,in the process e+e−→t¯t Z,the Higgs is exchanged as a virtual or a real particle and the eﬀect of H is,although small compared to h,important in order to restore the“GIM-like”cancellation discussed above.For both the tth and ttZﬁnal states processes,we denote the tree-level polarizeddiﬀerential-cross-section(DCS)byΣ(j)f,where f=tth or f=ttZ correspondingto the tth or ttZﬁnal states,respectively,and j=1(−1)for left(right)polarizedincoming electron beam.Σ(j)f can be subdivided into its CP-even(Σ+(j)f)andCP-odd(Σ−(j)f)parts:Σ(j)f=Σ+(j)f+Σ−(j)f.(11) The CP-even and CP-odd DCS’s can be further broken to diﬀerent terms which correspond to the various Higgs coupling combinations and which transform as n under T N.For bothﬁnal states,f=tth and f=ttZ,we have:Σ+(j)f= i g i(n)+f F i(n)+(j)f,CP even,(12)Σ−(j)f= i g i(n)−f F i(n)−(j)f,CP odd,(13)where g i(n)+f ,g i(n)−f,n=+or−,are diﬀerent combinations of the Higgs couplingsa H t,b H t,c H and F i(n)+(j)f ,F i(n)−(j)f,again with n=+or−,are kinematical functions ofphase space which transform like n under T N.Let usﬁrst write the Higgs coupling combinations for the CP-even part.In the case of e+e−→t¯t h,neglecting the imaginary part in the s-channel Z propagator, we have four relevant coupling combinations[3,12]:g1(+) +tth =(a h t)2,g2(+)+tth=(b h t)2,g3(+)+tth=(c h)2,g4(+)+tth=a h t c h.(14)In the case of e+e−→t¯t Z,apart from the SM DCS,which corresponds to interfer-ence terms among the four SM diagrams represented by diagram(a)on the right hand side of Fig.1,and keeping terms proportional to both the real and imaginary parts of the Higgs propagator,ΠH,we get[4]:g1(+) +ttZ =(a H t c H)Re(ΠH),g2(−)+ttZ=(a H t c H)Im(ΠH),(15)g3(+) +ttZ =(a H t c H)2Re(ΠH),g4(+)+ttZ=(a H t c H)2Im(ΠH),(16)g5(+) +ttZ =(b H t c H)2Re(ΠH),g6(+)+ttZ=(b H t c H)2Im(ΠH),(17)where:ΠH≡ s+m2Z−m2H−2p·p Z+im HΓH −1.(18) p≡p−+p+andΓH is the width of H=h or H.For the CP-odd parts one gets:g1(−)−tth=b h t c h,(19)g1(−)−ttZ =b H t c H Re(ΠH),g2(+)−ttZ=b H t c H Im(ΠH).(20)The CP-even pieces,Σ+(j)f,yield the corresponding cross-sections(recall that f= tth or ttZ):σ(j)f= Σ+(j)f(Φ)dΦ,(21) whereΦstands for the phase-space variables.In Fig.2a and2b we plot the un-polarized cross-sections,σtth andσttZ as a function of m h and√025050075010001250150017502000m h or s 1/2 (GeV) 0.0 0.5 1.0 1.52.0σt t h (f b )s 1/2=1 TeVs 1/2=1.5 TeVm h =100 GeVm h =360 GeV (a)025050075010001250150017502000m h or s 1/2 (GeV) 01 2 3 4 5 6 78 9σt t Z (f b )s 1/2=1 TeV s 1/2=1.5 TeV m h =100 GeV m h =360 GeV (b)Figure 2:The cross sections (in fb)for:(a)the reaction e +e −→t ¯t h with tan β=0.5and (b)the reaction e +e −→t ¯tZ with tan β=0.3,assuming unpolarized electron and positron beams,for Model II with set II and as a function of m h (solid and dashed lines)and√s ≈750GeV and m h ∼>2m t .σtth drops with m h while σttZ grows in the range m h ∼<2m t .σttZ peaks at around m h ∼>2m t and drops as m h grows further.Moreover,σtth peaks at around√s ≈750GeV for both m h =100and 360GeV.As we will seelater,these diﬀerent features of the two cross-sections are,in part,the cause for the diﬀerent behavior of the CP-asymmetries discussed below.Let us now concentrate on the CP-odd T N -odd eﬀects in e +e −→t ¯th ;t ¯t Z ,ema-nating from the T N-odd pieces inΣ−(j)tth;Σ−(j)ttZ.From Eqs.19and20it is clear that the CP-violating piecesΣ−(j)tth;Σ−(j)ttZ have to be proportional to b h t c h(in the ttZ case there is an additional similar piece corresponding to the heavy Higgs H).The corresponding CP-odd kinematic functions,F1(−)−(j)tth ;F1(−)−(j)ttZ,being T N-odd,arepure tree-level quantities and are proportional to the only non vanishing Levi-Civita tensor present,ǫ(p−,p+,p t,p¯t),when the spins of the top are disregarded.The ex-plicit expressions for F1(−)−(j)fare:F1(−)−(j)tth =−12g3W m2ZΠZhΠZ T3t c Z jǫ(p−,p+,p t,p¯t)×j(Πh t+Πh¯t) (s−s t−m2h)(3w−j−w+j)+m2Z(w−j−w+j) + T3t c Z jΠZ(Πh t−Πh¯t)f ,(22)F1(−)−(j)ttZ =−√c3W2m2t2T3t c Z jΠZ±Q t s2W c2WΠγ,(26)where s W(c W)is the sin(cos)of the weak mixing angleθW,Q f and T3f are the chargeand z-component of the weak isospin of a fermion,respectively.c Z−1=1/2−s2W,c Z1=−s2W(recall that j=−1(1)for a left(right)handed electron).Since at tree level there cannot be any absorptive phases,only T N-odd,CP asymmetries are expected to occur inΣ−(j)f.Note that in the ttZ case there is aCP-odd T N-even piece,b H t c H Im(ΠH)×F2(+)−(j)ttZ(see Eq.20),in the DCS.However,being proportional to the absorptive part coming from the Higgs propagator,it is not a pure tree-level quantity.Simple examples of observables that can trace the tree-level CP-eﬀect in e +e −→t ¯th ;t ¯t Z are:O = p −·( p t × p ¯t )Σ+(j )tth ;Σ+(j )ttZ .(27)O opt (tth ;ttZ )are optimal observables in the sense that the statistical error,in the measured asymmetry,is minimized [15].As mentioned before,since the ﬁnal state consists of three particles,using only the available momenta,there is a unique an-tisymmetrical tensor that can be formed.Thus,both observables are proportional to ǫ(p −,p +,p t ,p ¯t )and O opt (tth ;ttZ )are related to O through a multiplication by a CP-even function.In the following we focus only on the CP-odd eﬀects coming from the optimal observables.However,we remark that the results for the simple observ-able O exhibit the same behavior,though slightly smaller then those for O opt .The theoretical statistical signiﬁcance,N SD ,in which an asymmetry can be measured in an ideal experiment is given by N SD =A √σ(σ=σtth ;σttZ for the tth ;ttZ ﬁnal states),where for the observables O and O opt ,the CP-odd quantity A ,deﬁned above,is:A O ≈ O / O opt .(28)Also,L is the eﬀective luminosity for fully reconstructed t ¯th or t ¯t Z events.In particular,we take L =ǫL ,where L is the total yearly integrated luminosity and ǫis the overall eﬃciency for reconstruction of the t ¯th or t ¯t Z ﬁnal states.For numerical results we have used set II deﬁned above for the angles α1,2,3,i.e.{α1,α2,α3}={π/2,π/4,0}(recall that for the tth ﬁnal state we choose tan β=0.5while for the ttZ ﬁnal state we choose tan β=0.3).Figs.3a and 3b show the ex-pected asymmetry and statistical signiﬁcance in the unpolarized case,corresponding to O opt in Model II for the tth and ttZ ﬁnal states,respectively.The asymmetry is plotted as a function of the mass of the light Higgs (m h )where again,m H =750GeV in the ttZ case.We plot N SD /√L =0.1will correspond to a one-sigma eﬀect).We remark that set II cor-50150250350450550650m h (GeV) 0.0 0.10.20.30.4 0.5A opt , s=1 TeVA opt , s=1.5 TeV N SD /L 1/2, s=1 TeV N SD /L 1/2, s=1.5 TeV (a)50150250350450550650750m h (GeV)0.0 0.10.20.3 0.4A opt , s=1 TeVA opt , s=1.5 TeVN SD /L 1/2, s=1 TeVN SD /L 1/2, s=1.5 TeV(b)Figure 3:The asymmetry,A opt ,and scaled statistical signiﬁcance,N SD /√s =1TeV and 1.5TeV.All graphs are with set II of the parameters,as in Fig.2.responds to the largest CP-eﬀect,though not unique.In the tth case tan β=0.5is favored,however,the eﬀect mildly depends on tan βin the range 0.3∼<tan β∼<1(see also [3]).In the ttZ case,the eﬀect is practically insensitive to α3and is roughly proportional to 1/tan β,it therefore drops as tan βis increased.Nonetheless,we ﬁnd that N SD /√50075010001250150017502000s 1/2 (GeV) 0.0 0.10.20.30.4 0.5A opt , m h =100 GeVA opt , m h =360 GeVN SD /L 1/2, m h =100 GeVN SD /L 1/2, m h =360 GeV (a)50075010001250150017502000s 1/2 (GeV)0.0 0.10.20.3 0.4A opt , m h =100 GeVA opt , m h =360 GeVN SD /L 1/2, m h =100 GeVN SD /L 1/2, m h =360 GeV(b)Figure 4:The asymmetry,A opt ,and scaled statistical signiﬁcance,N SD /√s ,form h =100GeV and m h =360GeV.All graphs are with set II of the parameters,as in Fig.2.m h =m H =750GeV,in which case the “GIM-like”mechanismdiscussed before applies.The scaled statistical signiﬁcance N SD /√L ≈0.12−0.2in the mass range 50GeV ∼<m h ∼<350GeV,for both √L on the c.m.energy,√s ≈1.1(1.5)TeV for m h =100(360)GeV and stays roughlythe same as √s ≈1TeV and then decreases as √are produced followed by the h decay h→t¯t,thus,the Higgs exchange diagram becomes more dominant.In Tables1and2we present N SD for O opt,for the tth and ttZ cases,respectively, in Model II with set II,and we also compare the eﬀect of beam polarization with the unpolarized case.As before,we take tanβ=0.5and tanβ=0.3for the tth and ttZ cases,respectively,where for the ttZ case we also present numbers for both m H=750GeV(shown in the parentheses)and m H=1TeV,to demonstrate the sensitivity of the CP-eﬀect to the mass of the heavy Higgs.For illustrative purposes,√we choose m h=100,160and360GeV and show the numbers fors=1.5TeV with L=500[fb]−1(see[1]).In both cases we takeǫ=0.5assuming that there is no loss of luminosity when the electrons are polarized(if the eﬃciency for t¯t h and/or ttZ reconstruction isǫ=0.25,then our numbers would correspondingly require2years of running).Evidently,for both reactions,left polarized incoming electrons can probe CP-violation slightly better than unpolarized ones.We can see that in the tth case the CP-eﬀect drops as the mass of the light Higgs h grows,while in the ttZ case√it grows with m h.In particular,weﬁnd that withs=1TeV and m h=360GeV,the ttZ case is much more sensitive to O opt and the eﬀect can reach2.2σfor left polarized electron beam.However, with that c.m.energy,the tth mode gives a better CP-odd eﬀect in the range 100GeV∼<m h∼<160GeV.Before continuing,let us summarize the above results and add some concluding remarks.We have shown that an extremely interesting CP-odd signal may arise at tree-level in the reactions e+e−→t¯t h and e+e−→t¯t Z.The asymmetries that were found are∼15%−35%in the tth case and∼7%−8%for the ttZﬁnal state.TheseTable1:The statistical signiﬁcance,N SD,in which the CP-nonconserving eﬀects in e+e−→t¯t h can be detected in one year of running of a future high energy collider with either unpolarized or polarized incoming electron beam.We have used√tanβ=0.5,a yearly integrated luminosity of L=200and500[fb]−1fore+e−→t¯t h(Model II with Set II)s j(TeV)⇓(GeV)⇒m h=1602.2 1.12.0 1.01.80.9-13.91.5unpol3.513.1e+e−→t¯t Z(Model II with Set II)s j(TeV)⇓(GeV)⇒m h=160(1.8)1.7(2.2)2.2(1.6)1.6(2.0)2.0(1.5)1.5(1.8)1.8-1(2.4)3.01.5unpol(2.1)2.71(1.8)2.3asymmetries can give rise to a∼3−4σCP-odd signals in a future e+e−collider running with c.m.energies in the range1TeV∼<√,(29)s2can be constructed.We have considered this observable for the reaction e+e−→t¯t h→bW+¯bW−h in[3].We found there that,close to threshold,this observable is not very eﬀective.However at higher energies,O b is about as sensitive as the simple triple product correlation O deﬁned in Eq.27and,therefore,slightly less sensitive then O opt.Note also that for the light Higgs mass,m h=100GeV,the most suitable way to detect the Higgs in e+e−→t¯t h→bW+¯bW−h is via h→b¯b with branching ratio∼1.For m h∼>2m t,and speciﬁcally with set II used above,there are two competing Higgs decays,h→t¯t and h→W+W−,depending on the value of tanβ. For example,for tanβ=0.5,as was chosen above,one has Br(h→t¯t)≈0.77 and Br(h→W+W−)≈0.17,thus,the h→t¯t mode is more adequate.Of course, h→t¯t will dominate more for smaller values of tanβand less if tanβ>0.5. In particular,for tanβ=0.3(1)one has Br(h→t¯t)≈0.89(0.57)and Br(h→W+W−)≈0.08(0.32).As emphasized before,theﬁnal states t¯t h and t¯t Z,and in particular the t¯t h, are expected to be the center of considerable attention at a future linear collider.Extensive studies of these reactions are expected to teach us about the details ofthe couplings of Higgs to the top quark.Thus,it is gratifying that the sameﬁ-nal states promise to exhibit interesting eﬀects of CP violation.It would be veryinstructive to examine the eﬀects in other extended models.Numbers emergingfrom the2HDM that was used especially with the speciﬁc value of the parameters,should be viewed as an illustrative example.The important point is that the reac-tions e+e−→t¯t h→bW+¯bW−h and e+e−→t¯t Z→bW+¯bW−Z appear to be very powerful and very clean tools for extracting valuable information on the parametersof the underlying model for CP violation.3.e+e−→t¯cνe¯νe,t¯c e+e−;Cases of Tree-Level Flavor-Changing-Scalar Tran-sitionsThe reactions:e+e−→t¯cνe¯νe;¯t cνe¯νe,e+e−→t¯c e+e−;¯t ce+e−,(30) occur via W+W−or ZZ fusion(see Fig.5).The FCS transitions in those reactions gives rise to appreciable cross-sections,at the level of few fb’s[6],which should be accessible to the Next generation of e+e−Linear Colliders.The crucial interesting feature of the V V fusion reactions is that,being a t-channel fusion process,the corresponding cross-sections grow with the c.m.energy√of the collider.Therefore,even if no t¯c events are detected ats=0.5−2TeV due to a severe CKM suppression[6].We therefore neglect theSM contribution in the following.e e h H νeeee νt (e)(e)d,s,bW(Z)c ,(a)(b)W(Z)W νtcW νe e Figure 5:(a)The Standard Model diagram for e +e −→t ¯c νe ¯νe ;(b)Diagrams for e +e −→t ¯c νe ¯νe (e +e −)in Model III.In Model III,where the tc H coupling of Eq.4are present,V V →t ¯c pro-ceeds at tree-level via the ˆs -channel neutral Higgs exchange of diagram (b)in Fig.5.Neglecting the SM diagram,the corresponding parton-level cross-sectionˆσV ≡ˆσ(V 1λ1V 2λ2→t ¯c)is given by [6]:4ˆσV =(sin 2˜α)2N c πα2m W 4|ǫV 1λ1·ǫV 2λ2|2|Πh −ΠH |2×m t m c √1−4m 2ℓ/ˆs,(32)and:ΠH =14V 1=W +,V 2=W −for W +W −fusion and V 1=V 2=Z for ZZ fusion.For deﬁniteness,we will ignore CP violation and take λI =0and λ=λR in Eq.4.In calculating the full cross sections,i.e.σννtc ≡σ(e +e −→t ¯c νe ¯νe +¯t cνe ¯νe )and σeetc ≡σ(e +e −→t ¯c e +e −+¯tce +e −),we used the eﬀective vector boson approximation (EVBA)[16].An exact calculation of σννtc ,using 2→4helicity amplitudes,wasperformed in [7],where it was found that,in the ranges where σννtc ∼>1fb,the diﬀerence between the EVBA and the exact calculation is about ∼10%.Note alsofrom Eq.31,that ˆσW →ˆσZ for m W →m Z .The main diﬀerence between σννtc and σeetc then arises from the dissimilarity between the distribution functions for W and Z bosons,and we ﬁnd that σννtc ≈10×σeetc (for more details see [6]).Therefore,below we present an analysis of σννtc only,keeping in mind that σeetc exhibits the same behavior though suppressed by about an order of magnitude.As mentioned in the introduction,only two out of the three neutral Higgs parti-cles are relevant for the present analysis.The reason is that,in the FC case also,only h and H can simultaneously have a coupling to a vector boson and a FC coupling to t ¯c .therefore there is a “GIM-like”cancellation in the scalar sector,operative also in the ﬂavor-changing eﬀects of Model III.In particular,the choice ˜α=π/4,for which the tch and tcH couplings are identical (see Eq.4),is special in the sense that for this value the “GIM-like”cancellation mentioned above is most eﬀective.Thus,for degenerate h and H masses and with ˜α=π/4,the cross-section σννtc vanishes.However,for ˜α=π/4,this “GIM-like”cancellation is only partly eﬀectiveand σννtc ∼>1fb is still possible,even with m H =m h .In Fig.6we show the dependence of the scaled cross-section σννtc /λ2on the mass of the light Higgs m h for four values of s and for ˜α=π/4.5The cross-section peaks at m h ≃250GeV and drops as the mass of the light Higgs approaches that of the heavy Higgs due to the “GIM-like”cancellation discussed above.For c.m.energies of √s∼>1TeV and an integrated luminosity of the order of L ∼>102[fb]−1,Model III (with λ=1)predicts hundreds and up to thousands of t ¯c νe ¯νe events and several tens to hundreds of t ¯c e +e −events.For example,with√5The scaled cross-section,σννtc /λ2,has a residual mild dependence on λthrough its dependence on the Higgs particles widths,ΓH .1002003004005006007008009001000m h (GeV)0.00.51.01.52.02.53.03.54.04.55.05.56.0σννtc/λ2(fb )s 1/2=0.5 TeVs 1/2=1 TeVs 1/2=1.5 TeV s 1/2=2 TeVm H =1 TeVFigure 6:The cross-section σ(e +e −→t ¯c νe ¯νe +¯t cνe ¯νe )in units of λ2as a function ofm h for √s =1.5TeV.Thecorresponding SM prediction yields,as mentioned above,essentially zero events.In Fig.7we show the dependence of σννtc /λ2on (sin ˜α)2for m h =250GeV,√s in the range 0.5–2TeV.Wesee that in the large splitting case,i.e.m H =1TeV,σννtc (π/14∼<˜α∼<π/4)>σννtc (˜α=π/4).Moreover,even for (m H −m h )=0,σννtc∼>1fb is still possible for 0.02∼<(sin ˜α)2∼<0.22and 0.78∼<(sin ˜α)2∼<0.98.In fact,our analysis shows that,with moderate restrictions on ˜α,σννtc remains well above the fb level for √。

一种新的基于奇异值分解的小波域盲水印

ＡｂｔａｔＡｔｐｅｅ，ｈｗｏｉｒｖｈｅｒｂｔｅｓｏｏｕｓｔｒｒｉｇａａｎｔｇｏｔｉａｔａｓ，ｅｐｅｉｌｔａｋｆｓｒｃ：ｒｓｎｔｏｔｍｐｏｅｔｏｕｓｎｓｆｒｂｔｗａｅｍａｋｎｇｉｓｅｍｅｒｃｌａｔｃｋｓｃａｌａｔｃｓｏｙ
ａｄａｖｎａｅｆｉｒｔｗｖｌａｓｒＤ）ｔｉｐｐｒｒｐｓｄａｎｖｌｌｄｗｔｒａｋｇｂｓｄｏＶｎＷＴｎｄａｔｓｓｅａｅｔｒｎｆｍ（ＷＴ，ｓａｅｏｏｅｏｅｂｉａｍｒｉａｅｎＳＤａｄＤ，ｇｏｄｃｅｅｔｏｈｐｎｅｎ
ｄｉ１．９９ｊｉｎ１０ —６５２１．３１２ｏ：０３６／．ｓ．０１３９．００．０ｓ１
Ｎｏｅｌｎｔｒｒｉｇｂｓｄｏｉｇｌｒｖｌｂｉｄｗａｅｍａｋｎａｅｎｓｎｕａ
ｖｌｅｄｃｍｐｓｔｏｎｖｌｔｔａｓｏｍａｕｅｏｏｉｎａｄｗａｅｅｒｎｆｒｉ
Ａｉｕ．ＣＮＱｎＩ — ａＨＥｉＬｈｇ
（ｃｏｌｆｔａ— ｌｔｃｌＣｍｕｅｎｉｅｒｇ，ｎｖｒｔｈｎｈｉｏｃｎｅ＆ＴｃｎｌｙＳａｇａ００３，ｈｎ）Ｓｈｏｏｉｌｅｒａ＆ｏｐｔＥｇｎｅｎＵｉｓｙｏＳａｇａｒＳｉｃｃＥｃｉｒｉｅｉｆｆｅｅｈｏｏ，ｈｎｈｉ０９Ｃｉａｇ２
第２８卷第３期２１０１年３月

2022年新高考全国Ⅱ卷英语真题(解析版)

2.How many chaperones are needed for a group of 30 children to visit the Museum?
A.One.B.Two.C.Three.D.Four.
3.What are children prohibited from doing at the Museum?
6.What does the author think of himself?
A.Socially ambitious.B.Physically attractive.
C.Financially independent.D.Digitally petent.
7.What can we learn about the author as a journalist?
【2题详解】
细节理解题。根据“Group Size”标题下“We require one chaperone (监护人) per ten children.(我们要求每十个孩子有一个监护人)”可知，10个孩子需要1个监护人，那么30个孩子则需要3个监护人。故选C。
3题详解】
细节理解题。根据“Guidelines”标题下“Children are not allowed unacpanied in all areas of the Museum.(无人陪伴的儿童不得进入博物馆的所有区域)”可知，儿童必须在监护人陪伴下才能进入博物馆，即儿童不能单独进入博物馆进行探索。与选项D“Exploring the place alone.(独自探索博物馆)”属于同义替换，故选D。
A.He lacks experience in his job.B.He seldom appears on television.

Building and Environment

逄秀锋，等：我国建筑调适发展现状与前景指南与标准、建立激励机制以及政策法规、走向市场化产业化。

我国建筑调适的发展目前也遵循了这样一条发展路径，不同的是，我们的目标是用更短的时间完成西方国家四十多年走过的道路。

参考文献：［1］Mills E．Commissioning Capturing the Potential［J］．ASHRAE Journal，2011，53（2）：1－2．［2］逄秀锋，刘珊，曹勇．建筑设备与系统调适［M］．北京：中国建筑工业出版社，2015：1－2．［3］Legris C，Choiniere D，Milesi Ferretti．Annex47Report1：Commissioning Overview［R］．Paris：International Energy Agency，2010．［4］The U．S．Department of Energy．New DOE Research Strengthens Business Case for Building Commissioning［EB/OL］．（2019－05－02）［2020－01－02］．https：//www．energy．gov/eere/buildings/articles/ new-doe-research-strengthens-business-case-building-commissioning．作者简介：逄秀锋（1976），男，辽宁人，毕业于美国内布拉斯加大学林肯分校，暖通空调专业，博士，研究员，研究方向：建筑调适技术、建筑系统能耗模拟、暖通空调系统故障诊断与优化控制、智慧建筑（xpang113@163．com）。

Energy and Buildingshttps：//www．sciencedirect．com/journal/energy-and-buildings/vol/224/suppl/CVolume224，1October2020（1）A new analytical model for short-time analysis of energypiles and its application，by Jian Lan，Fei Lei，Pingfang Hu，Na Zhu，Article110221Abstract：An energy pile is a special form of vertical ground heatexchanger that couples the roles of structural support and heat trans-fer．Modeling the transient heat transfer process inside an energy pilehas importance；however，available analytical models either have in-sufficient calculation accuracy or are computationally demanding．Based on three existing models，this paper proposes a novel short-term hybrid composite-medium line-source（HCMLS）model，whichis not only efficient in computation but also more accurate than mosttraditional analytical models．The model is suitable for ground heatexchangers of various radii．Comparisons between the hybrid analyti-cal model and a numerical model are made for energy pile cases withdifferent parameters，including the thermal properties，borehole radii，relative positions of tubes，and number of tubes．In general，the hy-brid composite-medium line-source model gives credible predictionafter100min．The new model is further validated by the infinitecomposite-medium line-source（ICMLS）model，which is currentlythe most theoretically complete short-term model．Moreover，the newmodel is applied to thermal response tests（TRTs）．The least dimen-sionless test duration for interpretations based on the modified hybridcomposite-medium line-source（C-HCMLS）solution is Fo＞1.7．This study renders the application of in situ TRTs to energy pileswith large diameters feasible．Keywords：Ground heat exchanger；Energy pile；Short time re-sponse；Thermal response testing（2）Charging performance of latent thermal energy storage sys-tem with microencapsulated phase-change material for domestichot water，by Y．Fang，Z．G．Qu，J．F．Zhang，H．T．Xu，G．L．Qi，Arti-cle110237（3）Thermographic2D U-value map for quantifying thermalbridges in building fa ades，by Blanca Tejedor，Eva Barreira，Ricardo M．S．F．Almeida，Miquel Casals，Article110176（4）Urban morphology and building heating energy con-sumption：Evidence from Harbin，a severe cold region city，by Hong Leng，Xi Chen，Yanhong Ma，Nyuk Hien Wong，Tingzhen Ming，Article110143（5）UK Passivhaus and the energy performance gap，by Ra-chel Mitchell，Sukumar Natarajan，Article110240Building and Environmenthttps：//www．sciencedirect．com/journal/building-and-environ-ment/vol/183/suppl/CVolume183，October2020（1）Residential buildings airtightness frameworks：A reviewon the main databases and setups in Europe and NorthAmerica，by Irene Poza-Casado，Vitor E．M．Cardoso，Ricar-do M．S．F．Almeida，et al，Article107221Abstract：The airtightness of buildings has gained relevance in thelast decade．The spread of the regulatory frameworks，the demand ofstricter requirements，schemes for testing and quality control，the cre-ation of airtightness databases and its analysis，is proof of this real-ity．The present review encompasses schemes developed in Europeand North America with regard to these aspects for national residen-tial sectors．A normative framework on requirements and recommen-dations at the national level is compiled．Whole building airtightnessdatabases are compared based on their structures and measurementdata acquisition protocols．Gathered complementary information notdirectly related to testing is analysed and airtightness influencing fac-tors importance and relationships are discussed．Weaknesses andstrengths in the different aspects of the existing database setups areidentified．Also，neglected or not entirely undertaken topics are pin-pointed together with the suggestion of possible opportunities forfuture works and changes．Amongst other relevant remarks and dis-cussions，it is concluded that the lack of uniformization in methodbetween countries，the need for a minimum data setup，the lack ofdata analysis on relating the energy impact with the advancement inrequirements of airtightness performance and the implemented setupsare some of the main issues to address in the near future．Keywords：Review paper；Airtightness；Regulation policy（2）A simulation framework for predicting occupant thermalsensation in perimeter zones of buildings considering directsolar radiation and ankle draft，by Shengbo Zhang，Jamie P．Fine，Marianne F．Touchie，William O’Brien，Article107096（3）Comparative review of occupant-related energy aspectsof the National Building Code of Canada，by Ahmed Abdeen，William O’Brien，Burak Gunay，Guy Newsham，HeatherKnudsen，Article107136Applied Energyhttps：//www．sciencedirect．com/journal/applied-energy/vol/275/suppl/CVolume275，1October2020（1）Performance characteristics of variable conductance loopthermosyphon for energy-efficient building thermal control，byJingyu Cao，Xiaoqiang Hong，Zhanying Zheng，et al，Article115337Abstract：Variable conductance loop thermosyphon（VCLT）manip-ulates natural phase-change cycle to regulate the heat transfer．Its pri-mary advantages include high sustainability，simple design and lowcost．One of the potential applications of variable conductance loopthermosyphon is thermal control in buildings for achieving highenergy efficiency．In this study，a distributed steady-state model wasimplemented to determine the heat transfer control characteristics ofvariable conductance loop thermosyphon for the first time and evalu-ate its effectiveness on precise air-conditioning for buildings．The in-ternal flow resistance rises from0.002K/W to0．305K/W and theheat transfer rate decreases from468．5W to71．9W when the rela-tive opening degree of the regulating valve reduces from1.00to0.17under normal boundary conditions．The thermodynamic analysesshow that the regulating valve of the variable conductance loop ther-mosyphon can enable effective thermal control over a wide range ofheat transfer rate to accomplish indoor thermal comfort．The studyalso reveals that variable conductance loop thermosyphon can be ef-fectively adopted with various working fluids and over wide rangesof heat source and heat sink temperatures．Keywords：Air-conditioning；Energy-efficient building；Loop ther-mosyphon；Numerical study（2）Increasing the energy flexibility of existing district heatingnetworks through flow rate variations，by Jacopo Vivian，Dav-ide Quaggiotto，Angelo Zarrella，Article115411（3）A framework for uncertainty quantification in buildingheat demand simulations using reduced-order grey-box en-ergy models，by Mohammad Haris Shamsi，Usman Ali，EleniMangina，James O’Donnell，Article115141（2020－10－10《建筑节能》杂志社侯恩哲摘录）7。

面向极低功耗收发器的分数锁相环架构设计

文章编号：2095－6835（2020）13－0043－03面向极低功耗收发器的分数锁相环架构设计何昊晨（武汉理工大学自动化学院，湖北武汉430070）摘要：分数锁相环的毛刺是噪声耦合到带内的原因之一，导致收发器使用更高的功率实现等同的灵敏度。

针对该问题，提出一种基于可变幅度电荷泵（Variable Amplitude Charge Pump，VACP）和固定脉冲、可变周期信号发生器（Fixed Pulse Variable Period Signal Generator，FPVPSG）的低毛刺分数锁相环架构。

在FPVPSG的驱动下，VACP的输出电流脉冲不仅有固定位置、固定宽度、可变幅度，而且有可变周期，用于根除参考毛刺和分数毛刺。

基于Spectre的仿真结果表明，当参考频率f REF为20MHz，小数分频为120.13，且瞬态和锁定时的周期分别为1/f REF 和27/f REF时，20MHz及其整数倍的参考毛刺被根除，10MHz的分数毛刺较已有方案小19.67dB，且其他分数毛刺均远小于已有方案。

该结果表明推荐的分数锁相环架构可用于极低功耗收发器，在移动物联网和边缘计算领域有一定的应用前景。

关键词：极低功耗收发器；交调干扰；噪声；分数锁相环架构中图分类号：TN74文献标识码：A DOI：10.15913/ki.kjycx.2020.13.0161引言在移动物联网和边缘计算等领域，大部分收发器布局在户外或其他较难维护的场景，开发者应设计高性能的器件，用于尽可能降低收发器的功耗，使其具有较长的使用寿命。

分数锁相环（Fractional Phase-Locked Loop，FPLL）为收发器提供本振信号，将基带信号上变频到射频或者将接收信号下变频到基带，它的毛刺将恶化收发器的信噪比，导致发射器使用更高的发射功率实现等同的灵敏度，不利于节省收发器的功耗。

因此，研究更低毛刺的FPLL架构对实现极低功耗的收发器具有重要的意义，一直为学术界和工业界关注的研究热点。

一种基于复合混沌序列的扩频水印算法

（ｎｔｕｌｔｎｅｈｏｇ，ＩｆｒａｉｎＥｇｎｅｉｌＩｓｔｔｏｅｒｉＴｃｎｌｙＰＡＩｏｍｔｎｉｒｇｉｅｆＥｃｏｃｏｎｏｅｎ，ｈｎｚｏ５０４ｈｎ）Ｚｅｇｈｕ４００，Ｃｉａ
Ａｓｒｃ：ＴｉｐｐｒｕｒａｄａｏｕｔｐｅｄｓｅｔｍａｏｉｍｗｔｉｆｔｉＷＴｄｓｒｅａｅｔｒｎｆｍ）ｏｂｔｔｈｓａｅｔｏｗｒｒｂｓｓｒａｃｕｌｒｈｉｈｇｓｅＤ（ｉｅｖｌａｓｒｄ — ａｐｆｐｒｇｔｈｈａｙｎｃｔｗｅｔｏ
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对水印置乱，而后基于复合混沌二值序列对水印图案信号进行加密和扩频，给出了一种小波域中量化步长的并自适应确定方法，通过奇偶量化的方法将二值水印比特批量嵌入到载体的频域系数中。复合混沌密钥的使用与
小波域系数修改的隐蔽性，强了水印算法的安全性，于混沌序列扩频码的扩频水印技术增强了水印的鲁棒增基性，同时很好地兼顾了水印的不可见性，并且实现了水印信息的盲提取。
第２７卷第２期
２１００年２月