Experimental study of the decay PHI(1020)---ETA+GAMMA in multi-photon final state
Study of B - rho pi decays at Belle
a r X i v :h e p -e x /0207007v 1 1 J u l 2002BELLEBelle Prerpint 2002-18KEK Preprint 2002-59Study of B →ρπdecays at BelleBelle Collaboration A.Gordon u ,Y.Chao z ,K.Abe h ,K.Abe aq ,N.Abe at ,R.Abe ac ,T.Abe ar ,Byoung Sup Ahn o ,H.Aihara as ,M.Akatsu v ,Y.Asano ay ,T.Aso aw ,V.Aulchenko b ,T.Aushev ℓ,A.M.Bakich an ,Y.Ban ag ,A.Bay r ,I.Bedny b ,P.K.Behera az ,jak m ,A.Bondar b ,A.Bozek aa ,M.Braˇc ko t ,m ,T.E.Browder g ,B.C.K.Casey g ,M.-C.Chang z ,P.Chang z ,B.G.Cheon am ,R.Chistov ℓ,Y.Choi am ,Y.K.Choi am ,M.Danilov ℓ,L.Y.Dong j ,J.Dragic u ,A.Drutskoy ℓ,S.Eidelman b ,V.Eiges ℓ,Y.Enari v ,C.W.Everton u ,F.Fang g ,H.Fujii h ,C.Fukunaga au ,N.Gabyshev h ,A.Garmash b ,h ,T.Gershon h ,B.Golob s ,m ,R.Guo x ,J.Haba h ,T.Hara ae ,Y.Harada ac ,N.C.Hastings u ,H.Hayashii w ,M.Hazumi h ,E.M.Heenan u ,I.Higuchi ar ,T.Higuchi as ,L.Hinz r ,T.Hokuue v ,Y.Hoshi aq ,S.R.Hou z ,W.-S.Hou z ,S.-C.Hsu z ,H.-C.Huang z ,T.Igaki v ,Y.Igarashi h ,T.Iijima v ,K.Inami v ,A.Ishikawa v ,H.Ishino at ,R.Itoh h ,H.Iwasaki h ,Y.Iwasaki h ,H.K.Jang a ℓ,J.H.Kang bc ,J.S.Kang o ,N.Katayama h ,Y.Kawakami v ,N.Kawamura a ,T.Kawasaki ac ,H.Kichimi h ,D.W.Kim am ,Heejong Kim bc ,H.J.Kim bc ,H.O.Kim am ,Hyunwoo Kim o ,S.K.Kim a ℓ,T.H.Kim bc ,K.Kinoshita e ,S.Korpar t ,m ,P.Krokovny b ,R.Kulasiri e ,S.Kumar af ,A.Kuzmin b ,Y.-J.Kwon bc ,nge f ,ai ,G.Leder k ,S.H.Lee a ℓ,J.Li ak ,A.Limosani u ,D.Liventsevℓ,R.-S.Lu z,J.MacNaughton k,G.Majumder ao, F.Mandl k,D.Marlow ah,S.Matsumoto d,T.Matsumoto au,W.Mitaroffk,K.Miyabayashi w,Y.Miyabayashi v,H.Miyake ae,H.Miyata ac,G.R.Moloney u,T.Mori d,T.Nagamine ar,Y.Nagasaka i,T.Nakadaira as,E.Nakano ad, M.Nakao h,J.W.Nam am,Z.Natkaniec aa,K.Neichi aq, S.Nishida p,O.Nitoh av,S.Noguchi w,T.Nozaki h,S.Ogawa ap, T.Ohshima v,T.Okabe v,S.Okuno n,S.L.Olsen g,Y.Onuki ac, W.Ostrowicz aa,H.Ozaki h,P.Pakhlovℓ,H.Palka aa,C.W.Park o,H.Park q,L.S.Peak an,J.-P.Perroud r, M.Peters g,L.E.Piilonen ba,J.L.Rodriguez g,F.J.Ronga r, N.Root b,M.Rozanska aa,K.Rybicki aa,H.Sagawa h,S.Saitoh h,Y.Sakai h,M.Satapathy az,A.Satpathy h,e,O.Schneider r,S.Schrenk e,C.Schwanda h,k,S.Semenovℓ,K.Senyo v,R.Seuster g,M.E.Sevior u,H.Shibuya ap,V.Sidorov b,J.B.Singh af,S.Staniˇc ay,1,M.Stariˇc m,A.Sugi v, A.Sugiyama v,K.Sumisawa h,T.Sumiyoshi au,K.Suzuki h,S.Suzuki bb,S.Y.Suzuki h,T.Takahashi ad,F.Takasaki h, K.Tamai h,N.Tamura ac,J.Tanaka as,M.Tanaka h,G.N.Taylor u,Y.Teramoto ad,S.Tokuda v,S.N.Tovey u,T.Tsuboyama h,T.Tsukamoto h,S.Uehara h,K.Ueno z, Y.Unno c,S.Uno h,hiroda h,G.Varner g,K.E.Varvell an,C.C.Wang z,C.H.Wang y,J.G.Wang ba,M.-Z.Wang z,Y.Watanabe at,E.Won o,B.D.Yabsley ba,Y.Yamada h, A.Yamaguchi ar,Y.Yamashita ab,M.Yamauchi h,H.Yanai ac,P.Yeh z,Y.Yuan j,Y.Yusa ar,J.Zhang ay,Z.P.Zhang ak,Y.Zheng g,and D.ˇZontar aya Aomori University,Aomori,Japanb Budker Institute of Nuclear Physics,Novosibirsk,Russiac Chiba University,Chiba,Japand Chuo University,Tokyo,Japane University of Cincinnati,Cincinnati,OH,USAf University of Frankfurt,Frankfurt,Germanyg University of Hawaii,Honolulu,HI,USAh High Energy Accelerator Research Organization(KEK),Tsukuba,Japani Hiroshima Institute of Technology,Hiroshima,Japanj Institute of High Energy Physics,Chinese Academy of Sciences,Beijing,PRChinak Institute of High Energy Physics,Vienna,Austria ℓInstitute for Theoretical and Experimental Physics,Moscow,Russiam J.Stefan Institute,Ljubljana,Slovenian Kanagawa University,Yokohama,Japano Korea University,Seoul,South Koreap Kyoto University,Kyoto,Japanq Kyungpook National University,Taegu,South Korear Institut de Physique des Hautes´Energies,Universit´e de Lausanne,Lausanne,Switzerlands University of Ljubljana,Ljubljana,Sloveniat University of Maribor,Maribor,Sloveniau University of Melbourne,Victoria,Australiav Nagoya University,Nagoya,Japanw Nara Women’s University,Nara,Japanx National Kaohsiung Normal University,Kaohsiung,Taiwany National Lien-Ho Institute of Technology,Miao Li,Taiwanz National Taiwan University,Taipei,Taiwanaa H.Niewodniczanski Institute of Nuclear Physics,Krakow,Polandab Nihon Dental College,Niigata,Japanac Niigata University,Niigata,Japanad Osaka City University,Osaka,Japanae Osaka University,Osaka,Japanaf Panjab University,Chandigarh,Indiaag Peking University,Beijing,PR Chinaah Princeton University,Princeton,NJ,USAai RIKEN BNL Research Center,Brookhaven,NY,USAaj Saga University,Saga,Japanak University of Science and Technology of China,Hefei,PR ChinaaℓSeoul National University,Seoul,South Koreaam Sungkyunkwan University,Suwon,South Koreaan University of Sydney,Sydney,NSW,Australiaao Tata Institute of Fundamental Research,Bombay,Indiaap Toho University,Funabashi,Japanaq Tohoku Gakuin University,Tagajo,Japanar Tohoku University,Sendai,Japanas University of Tokyo,Tokyo,Japanat Tokyo Institute of Technology,Tokyo,Japanau Tokyo Metropolitan University,Tokyo,Japanav Tokyo University of Agriculture and Technology,Tokyo,Japanaw Toyama National College of Maritime Technology,Toyama,Japanay University of Tsukuba,Tsukuba,Japanaz Utkal University,Bhubaneswer,Indiaba Virginia Polytechnic Institute and State University,Blacksburg,VA,USAbb Yokkaichi University,Yokkaichi,Japanbc Yonsei University,Seoul,South KoreaB events collected with the Belle detector at KEKB.Thebranching fractions B(B+→ρ0π+)=(8.0+2.3+0.7−2.0−0.7)×10−6and B(B0→ρ±π∓)=(20.8+6.0+2.8−6.3−3.1)×10−6are obtained.In addition,a90%confidence level upper limitof B(B0→ρ0π0)<5.3×10−6is reported.Key words:ρπ,branching fractionPACS:13.25.hw,14.40.Nd1on leave from Nova Gorica Polytechnic,Nova Gorica,Sloveniamodes are examined.Here and throughout the text,inclusion of charge con-jugate modes is implied and for the neutral decay,B0→ρ±π∓,the notation implies a sum over both the modes.The data sample used in this analysis was taken by the Belle detector[9]at KEKB[10],an asymmetric storage ring that collides8GeV electrons against3.5GeV positrons.This produces Υ(4S)mesons that decay into B0B pairs.The Belle detector is a general purpose spectrometer based on a1.5T su-perconducting solenoid magnet.Charged particle tracking is achieved with a three-layer double-sided silicon vertex detector(SVD)surrounded by a central drift chamber(CDC)that consists of50layers segmented into6axial and5 stereo super-layers.The CDC covers the polar angle range between17◦and 150◦in the laboratory frame,which corresponds to92%of the full centre of mass(CM)frame solid angle.Together with the SVD,a transverse momen-tum resolution of(σp t/p t)2=(0.0019p t)2+(0.0030)2is achieved,where p t is in GeV/c.Charged hadron identification is provided by a combination of three devices: a system of1188aerogelˇCerenkov counters(ACC)covering the momentum range1–3.5GeV/c,a time-of-flight scintillation counter system(TOF)for track momenta below1.5GeV/c,and dE/dx information from the CDC for particles with very low or high rmation from these three devices is combined to give the likelihood of a particle being a kaon,L K,or pion, Lπ.Kaon-pion separation is then accomplished based on the likelihood ratio Lπ/(Lπ+L K).Particles with a likelihood ratio greater than0.6are identified as pions.The pion identification efficiencies are measured using a high momentum D∗+data sample,where D∗+→D0π+and D0→K−π+.With this pion selection criterion,the typical efficiency for identifying pions in the momentum region0.5GeV/c<p<4GeV/c is(88.5±0.1)%.By comparing the D∗+data sample with a Monte Carlo(MC)sample,the systematic error in the particle identification(PID)is estimated to be1.4%for the mode with three charged tracks and0.9%for the modes with two.Surrounding the charged PID devices is an electromagnetic calorimeter(ECL) consisting of8736CsI(Tl)crystals with a typical cross-section of5.5×5.5cm2 at the front surface and16.2X0in depth.The ECL provides a photon energy resolution of(σE/E)2=0.0132+(0.0007/E)2+(0.008/E1/4)2,where E is in GeV.Electron identification is achieved by using a combination of dE/dx measure-ments in the CDC,the response of the ACC and the position and shape of the electromagnetic shower from the ECL.Further information is obtained from the ratio of the total energy registered in the calorimeter to the particle momentum,E/p lab.Charged tracks are required to come from the interaction point and have transverse momenta above100MeV/c.Tracks consistent with being an elec-tron are rejected and the remaining tracks must satisfy the pion identification requirement.The performance of the charged track reconstruction is studied using high momentumη→γγandη→π+π−π0decays.Based on the relative yields between data and MC,we assign a systematic error of2%to the single track reconstruction efficiency.Neutral pion candidates are detected with the ECL via their decayπ0→γγ. Theπ0mass resolution,which is asymmetric and varies slowly with theπ0 energy,averages toσ=4.9MeV/c2.The neutral pion candidates are selected fromγγpairs by requiring that their invariant mass to be within3σof the nominalπ0mass.To reduce combinatorial background,a selection criteria is applied to the pho-ton energies and theπ0momenta.Photons in the barrel region are required to have energies over50MeV,while a100MeV requirement is made for photons in the end-cap region.Theπ0candidates are required to have a momentum greater than200MeV/c in the laboratory frame.Forπ0s from BE2beam−p2B and the energy difference∆E=E B−E beam.Here, p B and E B are the momentum and energy of a B candidate in the CM frame and E beam is the CM beam energy.An incorrect mass hypothesis for a pion or kaon produces a shift of about46MeV in∆E,providing extra discrimination between these particles.The width of the M bc distributions is primarily due to the beam energy spread and is well modelled with a Gaussian of width 3.3MeV/c2for the modes with a neutral pion and2.7MeV/c2for the mode without.The∆E distribution is found to be asymmetric with a small tail on the lower side for the modes with aπ0.This is due toγinteractions withmaterial in front of the calorimeter and shower leakage out of the calorimeter. The∆E distribution can be well modelled with a Gaussian when no neutral particles are present.Events with5.2GeV/c2<M bc<5.3GeV/c2and|∆E|< 0.3GeV are selected for thefinal analysis.The dominant background comes from continuum e+e−→qB events and jet-like qi,j|p i||p j|P l(cosθij)i,k|p i||p k|,r l=),where L s and L qqD0π+ decays.By comparing the yields in data and MC after the likelihood ratiorequirement,the systematic errors are determined to be4%for the modes with aπ0and6%for the mode without.Thefinal variable used for continuum suppression is theρhelicity angle,θh, defined as the angle between the direction of the decay pion from theρin the ρrest frame and theρin the B rest frame.The requirement of|cosθh|>0.3 is made independently of the likelihood ratio as it is effective in suppressing the background from B decays as well as the qB events is used[14].The largest component of this background is found to come from decays of the type B→Dπ;when the D meson decays via D→π+π−,events can directly reach the signal region while the decay D→K−π+can reach the signal region with the kaon misidentified as a pion.Decays with J/ψandψ(2S) mesons can also populate the signal region if both the daughter leptons are misidentified as pions.These events are excluded by making requirements on the invariant mass of the intermediate particles:|M(π+π−)−M D0|>0.14 GeV/c2,|M(π+π0)−M D+|>0.05GeV/c2,|M(π+π−)−M J/ψ|>0.07GeV/c2 and|M(π+π−)−Mψ(2S)|>0.05GeV/c2.The widest cut is made around the D0mass to account for the mass shift due to misidentifying the kaons in D0 decays as pions.Fig.1shows the∆E and M bc distributions for the three modes analysed after all the selection criteria have been applied.The∆E and M bc plots are shown for events that lie within3σof the nominal M bc and∆E values,respectively. The signal yields are obtained by performing maximum likelihoodfits,each using a single signal function and one or more background functions.The signal functions are obtained from the MC and adjusted based on comparisons of B+→B0are assumed to be equal.The M bc distribution for all modes isfitted with a single Gaussian and an ARGUS background function[15].The normalization of the ARGUS function is left tofloat and shape of the function isfixed from the∆E sideband:−0.25 GeV<∆E<−0.08GeV and5.2GeV/c2<M bc<5.3GeV/c2.For the mode with only charged pions in thefinal state,the∆E distribution isfitted with a single Gaussian for the signal and a linear function withfixed shape for the continuum background.The normalization of the linear function is left to float and the slope isfixed from the M bc sideband,5.2GeV/c2<M bc<5.26GeV/c2,|∆E|<0.3GeV.There are also other rare B decays that are expected to contaminate the∆E distribution.For the mode without aπ0,these modes are of the type B0→h+h−(where h denotes aπor K),B→ρρ(including all combinations of charged and neutralρmesons,where the polarizations of theρmesons are assumed to be longitudinal)and B→Kππ(including the decays B+→ρ0K+,B+→K∗0π+,B+→K∗0(1430)0π+,B+→f0(980)K+ and B+→f0(1370)K+)[16].These background modes are accounted for by using smoothed histograms whose shapes have been determined by combining MC distributions.The three B→ρρmodes are combined into one histogram. The normalization of this component is allowed tofloat in thefit due to the uncertainty in the branching fractions of the B→ρρmodes.Likewise,the B→hh and all the B→Kππmodes are combined to form one hh and one Kππcomponent.The normalizations of these components arefixed to their expected yields,which are calculated using efficiencies determined by MC and branching fractions measured by previous Belle analyses[16,17].The∆Efits for the modes with aπ0in thefinal state have the signal compo-nent modelled by a Crystal Ball function[18]to account for the asymmetry in the∆E distribution.As for the B+→ρ0π+mode,the continuum background is modelled by a linear function withfixed slope.Unlike the B+→ρ0π+mode, a component is included for the background from the b→c transition.The pa-rameterization for rare B decays includes one component for the B→Kππ0 modes(B0→ρ+K−and B0→K∗+π−)[19]and one for all the B→ρρmodes.The normalization of the B→ρρcomponent is left tofloat while the other components from B decays arefixed to their expected yields.Table1summarizes the results of the∆Efits,showing the number of events, signal yields,reconstruction efficiencies,statistical significance and branching fractions or upper limits for eachfit.The statistical significance is defined assystematic error in thefitted signal yield is estimated by independently varying eachfixed parameter in thefit by1σ.Thefinal results are B(B+→ρ0π+)=(8.0+2.3+0.7−2.0−0.7)×10−6and B(B0→ρ±π∓)=(20.8+6.0+2.8−6.3−3.1)×10−6where thefirst error is statistical and the second is systematic.For theρ0π0mode,one standard deviation of the systematic error is added to the statistical limit to obtain a conservative upper limit at90%confidence of5.3×10−6.The possibility of a nonresonant B→πππbackground is also examined.To check for this type of background,the M bc and∆E yields are determined for differentππinvariant mass bins.Byfitting the M bc distribution inππinvariant mass bins with B→ρπand B→πππMC distributions,the nonresonant contribution is found to be below4%.To account for this possible background, errors3.7%and3.2%are added in quadrature to the systematic errors of the ρ+π−andρ0π+modes,respectively.Theππinvariant mass distributions are shown in Fig.2.Two plots are shown for theρ+π−andρ0π+modes,one with events from the M bc sideband superimposed over the events from the signal region(upper)and one with events from signal MC superimposed over events from the signal region with the sideband subtracted(lower).Fig.3 shows the distribution of the helicity variable,cosθh,for the two modes with all selection criteria applied except the helicity condition.Events fromρπdecays are expected to follow a cos2θdistribution while nonresonant and other background decays have an approximately uniform distribution.The helicity plots are obtained byfitting the M bc distribution in eight helicity bins ranging from−1to1.The M bc yield is then plotted against the helicity bin for each mode and the expected MC signal distributions are superimposed.Both the ππmass spectrum and the helicity distributions provide evidence that the signal events are consistent with being fromρπdecays.The results obtained here can be used to calculate the ratio of branching frac-tions R=B(B0→ρ±π∓)/B(B+→ρ0π+),which gives R=2.6±1.0±0.4, where thefirst error is statistical and second is systematic.This is consistent with values obtained by CLEO[20]and BaBar[21,22]as shown in Table2. Theoretical calculations done at tree level assuming the factorization approx-imation for the hadronic matrix elements give R∼6[3].Calculations that include penguin contributions,off-shell B∗excited states or additionalππres-onances[4–8]might yield better agreement with the the measured value of R.In conclusion,statistically significant signals have been observed in the B→ρπmodes using a31.9×106BWe wish to thank the KEKB accelerator group for the excellent operation of the KEKB accelerator.We acknowledge support from the Ministry of Ed-ucation,Culture,Sports,Science,and Technology of Japan and the Japan Society for the Promotion of Science;the Australian Research Council and the Australian Department of Industry,Science and Resources;the National Science Foundation of China under contract No.10175071;the Department of Science and Technology of India;the BK21program of the Ministry of Education of Korea and the CHEP SRC program of the Korea Science and Engineering Foundation;the Polish State Committee for Scientific Research under contract No.2P03B17017;the Ministry of Science and Technology of the Russian Federation;the Ministry of Education,Science and Sport of the Republic of Slovenia;the National Science Council and the Ministry of Education of Taiwan;and the U.S.Department of Energy.References[1] A.E.Snyder and H.R.Quinn,Phys.Rev.D48,2139(1993).[2]I.Bediaga,R.E.Blanco,C.G¨o bel,and R.M´e ndez-Galain,Phys.Rev.Lett.81,4067(1998).[3]M.Bauer,B.Stech,and M.Wirbel,Z.Phys.C34,103(1987).[4] A.Deandrea et al.,Phys.Rev.D62,036001(2000).[5]Y.H.Chen,H.Y.Cheng,B.Tseng and K.C.Yang,Phys.Rev.D60,094014(1999).[6] C.D.Lu and M.Z.Yang,Eur.Phys.J C23,275(2002).[7]J.Tandean and S.Gardner,SLAC-PUB-9199;hep-ph/0204147.[8]S.Gardner and Ulf-G.Meißner,Phys.Rev.D65,094004(2002).[9]Belle Collaboration,A.Abashian et al.,Nucl.Instr.and Meth.A479,117(2002).[10]E.Kikutani ed.,KEK Preprint2001-157(2001),to appear in Nucl.Instr.andMeth.A.[11]G.C.Fox and S.Wolfram,Phys.Rev.Lett.41,1581(1978).[12]This modification of the Fox-Wolfram moments wasfirst proposed in a seriesof lectures on continuum suppression at KEK by Dr.R.Enomoto in May and June of1999.For a more detailed description see Belle Collaboration,K.Abe et al.,Phys.Lett.B511,151(2001).[13]CLEO Collaboration,D.M.Asner et al.,Phys.Rev.D53,1039(1996).[14]These MC events are generated with the CLEO group’s QQ program,see/public/CLEO/soft/QQ.The detector response is simulated using GEANT,R.Brun et al.,GEANT 3.21,CERN Report DD/EE/84-1,1984.[15]The ARGUS Collaboration,H.Albrecht et al.,Phys.Lett.B241,278(1990).[16]Belle Collaboration,A.Garmash et al.,Phys.Rev.D65,092005(2002).[17]Belle Collaboration,K.Abe et al.,Phys.Rev.Lett.87,101801(2001).[18]J.E.Gaiser et al.,Phys.Rev.D34,711(1986).[19]Belle Collaboration,K.Abe et al.,BELLE-CONF-0115,submitted as acontribution paper to the2001International Europhysics Conference on High Energy Physics(EPS-HEP2001).[20]CLEO Collaboration,C.P.Jessop et al.,Phys.Rev.Lett.85,2881(2000).[21]Babar Collaboration,B.Aubert et al.,submitted as a contribution paper tothe20th International Symposium on Lepton and Photon Interactions at High Energy(LP01);hep-ex/0107058.[22]BaBar Collaboration,B.Aubert et al.,submitted as a contribution paper tothe XXXth International Conference on High Energy Physics(ICHEP2000);hep-ex/0008058.Table1∆Efit results.Shown for each mode are the number of events in thefit,the signal yield,the reconstruction efficiency,the branching fraction(B)or90%confidence level upper limit(UL)and the statistical significance of thefit.Thefirst error in the branching fraction is statistical,the second is systematic.ρ0π+15424.3+6.9−6.29.68.0+2.3+0.7−2.0−0.74.4σρ+π−30144.6+12.8−13.46.820.8+6.0+2.8−6.3−3.13.7σρ0π0116−4.4±8.58.5<5.3-Experiment B(B0→ρ±π∓)×10−6B(B+→ρ0π+)×10−6RE v e n t s /16 M e VE v e n t s /3 M e V /c2(b) ρ0π+Signal backgrd02.557.51012.51517.52022.55.25.225 5.25 5.2755.3E v e n t s /18 M e VE v e n t s /2 M e V /c2(d) ρ+π-Signal backgrd051015202530355.25.225 5.25 5.2755.3∆E(GeV)E v e n t s /18 M e V(e) ρ0π024681012-0.2-0.10.10.2(GeV/c 2)E v e n t s /2 M e V /c2M bc (f) ρ0πSignal backgrd02468101214165.25.225 5.25 5.2755.3Fig.1.The ∆E (left)and M bc (right)fits to the three B →ρπmodes:ρ0π+,ρ+π−and ρ0π0.The histograms show the data,the solid lines show the total fit and the dashed lines show the continuum component.In (a)the contribution from the B →ρρand B →hh modes is shown by the cross hatched component.In (c)the cross hatched component shows the contribution from the b →c transition and B →ρρmodes.102030405060+0(GeV/c 2)E v e n t s /0.1 G e V /c2M(π+π0)(GeV/c 2)E v e n t s /0.1 G e V /c2(GeV/c 2)E v e n t s /0.1 G e V /c2+-(GeV/c 2)E v e n t s /0.1 G e V /c2M(π+ π-)510152025Fig.2.The M (ππ)distributions for B 0→ρ±π∓(left)and B +→ρ0π+(right)events in the signal region.Plots (a)and (b)show sideband events superimposed;plots (c)and (d)show the sideband subtracted plots with signal MC superimposed.-1-0.500.51M b c y i e l d (E v e n t s )cos θh-1-0.500.51M b c y i e l d (E v e n t s )cos θhFig.3.The ρmeson helicity distributions for B 0→ρ±π∓(a)and B +→ρ0π+(b).Signal MC distributions are shown superimposed.。
Study of the decay phi-- f0(980)g -- pi+pi-g with the KLOE detector
arXiv:hep-ex/0511031v2 24 Feb 2006
of High Energy Physics of Academica Sinica, Beijing, China. Nazionali di Frascati dell’INFN, Frascati, Italy.
Study of the decay φ →f0 (980)γ → π +π − γ with the KLOE detector
The KLOE Collaboration F. Ambrosino f , A. Antonelli b, M. Antonelli b, C. Bacci k, P. Beltrame c, G. Bencivenni b, S. Bertolucci b, C. Bini i, C. Bloise b, V. Bocci i, F. Bossi b, D. Bowring b,m, P. Branchini k, R. Caloi i, P. Campana b, G. Capon b, T. Capussela f , F. Ceradini k, S. Chi b, G. Chiefari f , P. Ciambrone b, S. Conetti m, E. De Lucia b, A. De Santis i, P. De Simone b, G. De Zorzi i, S. Dell’Agnello b, A. Denig c, A. Di Domenico i, C. Di Donato f , S. Di Falco g , B. Di Micco k, A. Doria f , M. Dreucci b, G. Felici b, A. Ferrari b, M. L. Ferrer b, G. Finocchiaro b, S. Fiore i, C. Forti b, P. Franzini i, C. Gatti b, P. Gauzzi i, S. Giovannella b, E. Gorini d, E. Graziani k, M. Incagli g, W. Kluge c, V. Kulikov e, F. Lacava i, G. Lanfranchi b, J. Lee-Franzini b,ℓ, D. Leone c, M. Martini b, P. Massarotti f , W. Mei b , S. Meola f , S. Miscetti b, M. Moulson b, S. M¨ uller c, F. Murtas b, M. Napolitano f , F. Nguyen k, M. Palutan b, E. Pasqualucci i, A. Passeri k, V. Patera b,h, F. Perfetto f , L. Pontecorvo i, M. Primavera d, P. Santangelo b, E. Santovetti j, G. Saracino f , B. Sciascia b, A. Sciubba b,h , F. Scuri g , I. Sfiligoi b, T. Spadaro b, M. Testa i, L. Tortora k, P. Valente i, B. Valeriani c, G. Venanzoni b, S. Veneziano i, A. Ventura d, S. Ventura i, R. Versaci c, G. Xu a,b ,
The decay $rho^{0}to pi^{+}+pi^{-}+gamma$ and the coupling constant g$_{rhosigmagamma}$
a rXiv:n ucl-t h /441v28Ma y2The decay ρ0→π++π−+γand the coupling constant g ρσγA.Gokalp ∗and O.Yilmaz †Physics Department,Middle East Technical University,06531Ankara,Turkey(February 8,2008)Abstract The experimental branching ratio for the radiative decay ρ0→π++π−+γis used to estimate the coupling constant g ρσγfor a set of values of σ-meson parameters M σand Γσ.Our results are quite different than the values of this constant used in the literature.PACS numbers:12.20.Ds,13.40.HqTypeset using REVT E XThe radiative decay processρ0→π++π−+γhas been studied employing different approaches[1,5].There are two mechanisms that can contribute to this radiative decay: thefirst one is the internal bremsstrahlung where one of the charged pions from the decay ρ0→π++π−emits a photon,and the second one is the structural radiation which is caused by the internal transformation of theρ-meson quark structure.Since the bremsstrahlung is well described by quantum electrodynamics,different methods have been used to estimate the contribution of the structural radiation.Singer[1]calculated the amplitude for this decay by considering only the bremsstrahlung mechanism since the decayρ0→π++π−is the main decay mode ofρ0-meson.He also used the universality of the coupling of theρ-meson to pions and nucleons to determine the coupling constant gρππfrom the knowledge of the coupling constant gρter,Renard [3]studied this decay among other vector meson decays into2π+γfinal states in a gauge invariant way with current algebra,hard-pion and Ward-identities techniques.He,moreover, established the correspondence between these current algebra results and the structure of the amplitude calculated in the single particle approximation for the intermediate states.In corresponding Feynman diagrams the structural radiation proceeds through the intermediate states asρ0→S+γwhere the meson S subsequently decays into aπ+π−pair.He concluded that the leading term is the pion bremsstrahlung and that the largest contribution to the structural radiation amplitude results from the scalarσ-meson intermediate state.He used the rough estimate gρσγ≃1for the coupling constant gρσγwhich was obtained with the spin independence assumption in the quark model.The coupling constant gρππwas determined using the then available experimental decay rate ofρ-meson and also current algebra results as3.2≤gρππ≤4.9.On the other hand,the coupling constant gσππwas deduced from the assumed decay rateΓ≃100MeV for theσ-meson as gσππ=3.4with Mσ=400MeV. Furthermore,he observed that theσ-contribution modifies the shape of the photon spectrum for high momenta differently depending on the mass of theσ-meson.We like to note, however,that the nature of theσ-meson as a¯q q state in the naive quark model and therefore the estimation of the coupling constant gρσγin the quark model have been a subject ofcontroversy.Indeed,Jaffe[6,7]lately argued within the framework of lattice QCD calculation of pseudoscalar meson scattering amplitudes that the light scalar mesons are¯q2q2states rather than¯q q states.Recently,on the other hand,the coupling constant gρσγhas become an important input for the studies ofρ0-meson photoproduction on nucleons.The presently available data[8] on the photoproduction ofρ0-meson on proton targets near threshold can be described at low momentum transfers by a simple one-meson exchange model[9].Friman and Soyeur [9]showed that in this picture theρ0-meson photoproduction cross section on protons is given mainly byσ-exchange.They calculated theγσρ-vertex assuming Vector Dominance of the electromagnetic current,and their result when derived using an effective Lagrangian for theγσρ-vertex gives the value gρσγ≃2.71for this coupling ter,Titov et al.[10]in their study of the structure of theφ-meson photoproduction amplitude based on one-meson exchange and Pomeron-exchange mechanisms used the coupling constant gφσγwhich they calculated from the above value of gρσγinvoking unitary symmetry arguments as gφσγ≃0.047.They concluded that the data at low energies near threshold can accommodate either the second Pomeron or the scalar mesons exchange,and the differences between these competing mechanisms have profound effects on the cross sections and the polarization observables.It,therefore,appears of much interest to study the coupling constant gρσγthat plays an important role in scalar meson exchange mechanism from a different perspective other than Vector Meson Dominance as well.For this purpose we calculate the branching ratio for the radiative decayρ0→π++π−+γ,and using the experimental value0.0099±0.0016for this branching ratio[11],we estimate the coupling constant gρσγ.Our calculation is based on the Feynman diagrams shown in Fig.1.Thefirst two terms in thisfigure are not gauge invariant and they are supplemented by the direct term shown in Fig.1(c)to establish gauge invariance.Guided by Renard’s[3]current algebra results,we assume that the structural radiation amplitude is dominated byσ-meson intermediate state which is depicted in Fig. 1(d).We describe theρσγ-vertex by the effective LagrangianL int.ρσγ=e4πMρMρ)2 3/2.(3)The experimental value of the widthΓ=151MeV[11]then yields the value g2ρππ2gσππMσ π· πσ.(4) The decay width of theσ-meson that follows from this effective Lagrangian is given asΓσ≡Γ(σ→ππ)=g2σππ8 1−(2Mπ2iΓσ,whereΓσisgiven by Eq.(5).Since the experimental candidate forσ-meson f0(400-1200)has a width (600-1000)MeV[11],we obtain a set of values for the coupling constant gρσγby considering the ranges Mσ=400-1200MeV,Γσ=600-1000MeV for the parameters of theσ-meson.In terms of the invariant amplitude M(Eγ,E1),the differential decay probability for an unpolarizedρ0-meson at rest is given bydΓ(2π)31Γ= Eγ,max.Eγ,min.dEγ E1,max.E1,min.dE1dΓ[−2E2γMρ+3EγM2ρ−M3ρ2(2EγMρ−M2ρ)±Eγfunction ofβin Fig.5.This ratio is defined byΓβRβ=,Γtot.= Eγ,max.50dEγdΓdEγ≃constant.(10)ΓσM3σFurthermore,the values of the coupling constant gρσγresulting from our estimation are in general quite different than the values of this constant usually adopted for the one-meson exchange mechanism calculations existing in the literature.For example,Titov et al.[10] uses the value gρσγ=2.71which they obtain from Friman and Soyeur’s[9]analysis ofρ-meson photoproduction using Vector Meson Dominance.It is interesting to note that in their study of pion dynamics in Quantum Hadrodynamics II,which is a renormalizable model constructed using local gauge invariance based on SU(2)group,that has the sameLagrangian densities for the vertices we use,Serot and Walecka[14]come to the conclusion that in order to be consistent with the experimental result that s-waveπN-scattering length is anomalously small,in their tree-level calculation they have to choose gσππ=12.Since they use Mσ=520MeV this impliesΓσ≃1700MeV.If we use these values in our analysis,we then obtain gρσγ=11.91.Soyeur[12],on the other hand,uses quite arbitrarly the values Mσ=500 MeV,Γσ=250MeV,which in our calculation results in the coupling constant gρσγ=6.08.We like to note,however,that these values forσ-meson parameters are not consistent with the experimental data onσ-meson[11].Our analysis and estimation of the coupling constant gρσγusing the experimental value of the branching ratio of the radiative decayρ0→π++π−+γgive quite different values for this coupling constant than used in the literature.Furthermore,since we obtain this coupling constant as a function ofσ-meson parameters,it will be of interest to study the dependence of the observables of the reactions,such as for example the photoproduction of vector mesons on nucleonsγ+N→N+V where V is the neutral vector meson, analyzed using one-meson exchange mechanism on these parameters.AcknowledgmentsWe thank Prof.Dr.M.P.Rekalo for suggesting this problem to us and for his guidance during the course of our work.We also wish to thank Prof.Dr.T.M.Aliev for helpful discussions.REFERENCES[1]P.Singer,Phys.Rev.130(1963)2441;161(1967)1694.[2]V.N.Baier and V.A.Khoze,Sov.Phys.JETP21(1965)1145.[3]S.M.Renard,Nuovo Cim.62A(1969)475.[4]K.Huber and H.Neufeld,Phys.Lett.B357(1995)221.[5]E.Marko,S.Hirenzaki,E.Oset and H.Toki,Phys.Lett.B470(1999)20.[6]R.L.Jaffe,hep-ph/0001123.[7]M.Alford and R.L.Jaffe,hep-lat/0001023.[8]Aachen-Berlin-Bonn-Hamburg-Heidelberg-Munchen Collaboration,Phys.Rev.175(1968)1669.[9]B.Friman and M.Soyeur,Nucl.Phys.A600(1996)477.[10]A.I.Titov,T.-S.H.Lee,H.Toki and O.Streltrova,Phys.Rev.C60(1999)035205.[11]Review of Particle Physics,Eur.Phys.J.C3(1998)1.[12]M.Soyeur,nucl-th/0003047.[13]S.I.Dolinsky,et al,Phys.Rep.202(1991)99.[14]B.D.Serot and J.D.Walecka,in Advances in Nuclear Physics,edited by J.W.Negeleand E.Vogt,Vol.16(1986).TABLESTABLE I.The calculated coupling constant gρσγfor differentσ-meson parametersΓσ(MeV)gρσγ500 6.97-6.00±1.58 8008.45±1.77600 6.16-6.68±1.85 80010.49±2.07800 5.18-9.11±2.64 90015.29±2.84900 4.85-10.65±3.14 90017.78±3.23Figure Captions:Figure1:Diagrams for the decayρ0→π++π−+γFigure2:The photon spectra for the decay width ofρ0→π++π−+γ.The contributions of different terms are indicated.Figure3:The pion energy spectra for the decay width ofρ0→π++π−+γ.The contri-butions of different terms are indicated.Figure4:The decay width ofρ0→π++π−+γas a function of minimum detected photon energy.Figure5:The ratio Rβ=Γβ。
Quarks——介绍夸克的英文资料
QuarksQuarks and Leptons are the building blocks which build up matter, i.e., they are seen as the "elementary particles". In the present standard model, there are six "flavors" of quarks. They can successfully account for all known mesons and baryons (over 200). The most familiar baryons are the proton and neutron, which are each constructed from up and down quarks. Quarks are observed to occur only in combinations of two quarks (mesons), three quarks (baryons). There was a recent claim of observation of particles with five quarks (pentaquark), but further experimentation has not borne it out.Quark Symbol Spin Charge BaryonNumberS C B T Mass*Up U 1/2 +2/3 1/3 0 0 0 0 1.7-3.3 MeV Down D 1/2 -1/3 1/3 0 0 0 0 4.1-5.8 MeV Charm C 1/2 +2/3 1/3 0 +1 0 0 1270 MeV Strange S 1/2 -1/3 1/3 -1 0 0 0 101 MeV Top T 1/2 +2/3 1/3 0 0 0 +1 172 GeVBottom B 1/2 -1/3 1/3 0 0 -1 0 4.19 GeV(MS) 4.67 GeV(1S)*The masses should not be taken too seriously, because the confinement of quarks implies that we cannot isolate them to measure their masses in a direct way. The masses must be implied indirectly from scattering experiments. The numbers in the table are very different from numbers previously quoted and are based on the July 2010 summary in Journal of Physics G, Review of Particle Physics, Particle Data Group. A summary can be found on the LBL site. These masses represent a strong departure from earlier approaches which treated the masses for the U and D as about 1/3 the mass of a proton, since in the quark model the proton has three quarks. The masses quoted are model dependent, and the mass of the bottom quark is quoted for two different models. But in other combinations they contribute different masses. In the pion, an up and an anti-down quark yield a particle of only 139.6 MeV of mass energy, while in the rho vector meson the same combination of quarks has a mass of 770 MeV! The masses of C and S are from Serway, and the T and B masses are from descriptions of the experiments in which they were discovered.Each of the six "flavors" of quarks can have three different "colors". The quark forces are attractive only in "colorless" combinations of three quarks (baryons), quark-antiquark pairs (mesons) and possibly larger combinations such as the pentaquark that could also meet the colorless condition. Quarks undergo transformations by the exchange of W bosons, and those transformations determine the rate and nature of the decay of hadrons by the weak interaction.Why "quark"?Has anyone ever seen a quark?What is the evidence for quarks inside protons?What is the evidence for six quarks?IndexParticle conceptsReferenc es Serway Ch. 47Rohlf Ch. 17Griffiths Ch. 1HyperPhysics***** Quantum Physics R Nave Go BackWhy "Quark"?The name "quark" was taken by Murray Gell-Mann from the book "Finnegan's Wake"by James Joyce. The line "Three quarks for Muster Mark..." appears in the fancifulbook. Gell-Mann received the 1969 Nobel Prize for his work in classifying elementary particles.IndexParticleconceptsHyperPhysics ***** Quantum PhysicsR Nave Go BackUp and Down QuarksThe up and down quarks are the most common and least massive quarks, being the constituents of protons and neutrons and thus of most ordinary matter.The fact that the free neutron decaysand nuclei decay by beta decay in processes likeis thought to be the result of a more fundamental quark processTable of quark propertiesIndexParticle conceptsHyperPhysics ***** Quantum PhysicsR Nave Go BackThe Strange QuarkIn 1947 during a study of cosmic ray interactions, a product of a proton collision with a nucleus was found to live for much longer time than expected: 10-10 seconds instead ofthe expected 10-23 seconds! This particle was named the lambda particle (Λ0) and the property which caused it to live so long was dubbed "strangeness" and that name stuck to be the name of one of the quarks from which the lambda particle is constructed. The lambda is a baryon which is made up of three quarks: an up, a down and a strange quark.The shorter lifetime of 10-23seconds was expected because the lambda as a baryon participates in the strong interaction, and that usually leads to such very short lifetimes. The long observed lifetime helped develop a new conservation law for such decays called the "conservation of strangeness". The presence of a strange quark in a particle is denoted by a quantum number S=-1. Particle decay by the strong or electromagnetic interactions preserve the strangeness quantum number. The decay process for the lambda particle must violate that rule, since there is no lighter particle which contains a strange quark - so the strange quark must be transformed to another quark in theprocess. That can only occur by the weak interaction, and that leads to a much longer lifetime. The decay processes show that strangeness is not conserved:The quark transformations necessary to accomplish these decay processes can be visualized with the help of Feynmann diagrams.The omega-minus, a baryon composed of three strange quarks, is a classicexample of the need for the property called "color" in describing particles.Since quarks are fermions with spin 1/2, they must obey the Pauliexclusion principle and cannot exist in identical states. So with threestrange quarks, the property which distinguishes them must be capable ofat least three distinct values.Conservation of strangeness is not in fact an independent conservation law, but can be viewed as a combination of the conservation of charge, isospin, and baryon number. It is often expressed in terms of hypercharge Y, defined by:Isospin and either hypercharge or strangeness are the quantum numbers often used to draw particle diagrams for the hadrons.Table of quark properties IndexParticle conceptsHyperPhysics***** Quantum Physics R Nave Go BackThe Charm QuarkIn 1974 a meson called the J/Psi particle was discovered. With a mass of 3100 MeV,over three times that of the proton, this particle was the first example of another quark, called the charm quark. The J/Psi is made up of a charm-anticharm quark pair.The lightest meson which contains a charm quark is the D meson. It provides interesting examples of decay since the charm quark must be transformed into a strange quark by the weak interaction in order for it to decay.One baryon with a charm quark is a called a lambda with symbol Λ+c . It has a composition udc and a mass of 2281 MeV/c2.Table of quark properties IndexParticle conceptsHyperPhysics***** Quantum Physics R Nave Go BackThe Top QuarkConvincing evidence for the observation of the top quark was reported by Fermilab's Tevatron facility in April 1995. The evidence was found in the collision products of 0.9 TeV protons with equally energetic antiprotons in the proton-antiproton collider. The evidence involved analysis of trillions of 1.8 TeV proton-antiproton collisions. The Collider Detector Facility group had found 56 top candidates over a predicted background of 23 and the D0 group found 17 events over a predicted background of 3.8. The value for the top quark mass from the combined data of the two groups after the completion of the run was 174.3 +/- 5.1 GeV. This is over 180 times the mass of a proton and about twice the mass of the next heaviest fundamental particle, the Z0 vector boson at about 93 GeV.The interaction is envisioned as follows: IndexParticle concept sReferen ce Ladbur yD-ZeroTable of quark propertiesHyperPhysics***** Quantum Physics R Nave Go BackConfinement of QuarksHow can one be so confident of the quark model when no one has ever seen an isolated quark? There are good reasons for the lack of direct observation. Apparently the color force does not drop off with distance like the other observed forces. It is postutated that it may actually increase with distance at the rate of about 1 GeV per fermi. A free quark is not observed because by the time the separation is on an observable scale, the energy is far above the pair production energy for quark-antiquark pairs. For the U and D quarks the masses are 10s of MeV so pair production would occur for distances much less thana fermi. You would expect a lot of mesons (quark-antiquark pairs) in very high energy collision experiments and that is what is observed.Basically, you can't see an isolated quark because the color force does not let them go, and the energy required to separate them produces quark-antiquark pairs long before they are far enough apart to observe separately.One kind of visualization of quark confinement is called the "bag model". One visualizes the quarks as contained in an elastic bag which allows the quarks to move freely around, as long as you don't try to pull them further apart. But if you try to pull a quark out, the bag stretches and resists.Another way of looking at quark confinement is expressed by Rohlf. "When we try to pull a quark out of a proton, for example by striking the quark with another energetic particle, the quark experiences a potential energy barrier from the strong interaction that increases with distance." As the example of alpha decay demonstrates, having a barrier higher than the particle energy does not prevent the escape of the particle - quantum mechanical tunneling gives a finite probability for a 6 MeV alpha particle to get through a 30 MeV high energy barrier. But the energy barrier for the alpha particle is thin enough for tunneling to be effective. In the case of the barrier facing the quark, the energy barrier does not drop off with distance, but in fact increases.Evidence for quarks in deep inelastic scattering IndexParticle conceptsReferenc eRohlf Sec 6-6HyperPhysics***** Quantum Physics R Nave Go Back The Bottom QuarkIn 1977, an experimental group at Fermilab led by Leon Lederman discovered a new resonance at 9.4 GeV/c^2 which was interpreted as a bottom-antibottom quark pair and called the Upsilon meson. From this experiment, the mass of the bottom quark is implied to be about 5 GeV/c^2. The reaction being studied waswhere N was a copper or platinum nucleus. The spectrometer had a muon-pair mass resolution of about 2%, which allowed them to measure an excess of events at 9.4 GeV/c^2. This resonance has been subsequently studied at other accelerators with a detailed investigation of the bound states of the bottom-antibottom meson.Table of quark properties IndexParticle conceptsReferenc eRohlf Ch. 17HyperPhysics***** Quantum Physics R Nave Go Back。
中考英语科学实验创新思考单选题40题
中考英语科学实验创新思考单选题40题1.In the science experiment, we need some tools. What is not a necessary tool? A. test tube B. hammer C. beaker D. microscope 答案：B。
本题考查科学实验中工具的名词。
A 选项“test tube”是试管，在化学实验等中常用；C 选项“beaker”是烧杯，也是科学实验常见工具；D 选项“microscope”是显微镜，在生物等实验中可能用到。
而B 选项“hammer”是锤子，一般不是科学实验的必要工具。
2.The scientist put a liquid in the _____. A. flask B. book C. pen D. box答案：A。
A 选项“flask”是烧瓶，可用于装液体进行实验；B 选项“book”是书，不能装液体；C 选项“pen”是笔，也不能装液体；D 选项“box”是盒子，通常不用于装实验液体。
3.We observe the reaction in the _____. A. table B. chair C. dish D. petri dish答案：D。
“petri dish”是培养皿，可用于观察实验反应；A 选项“table”是桌子；B 选项“chair”是椅子；C 选项“dish”通常指盘子，一般不用于观察实验反应。
4.The experiment needs a certain amount of _____. A. water B. breadC. stoneD. wood答案：A。
科学实验中常需要水，A 选项正确；B 选项“bread”是面包；C 选项“stone”是石头；D 选项“wood”是木头，都不是实验通常需要的量的物质。
5.In the chemistry experiment, we use ____ to measure the volume.A. rulerB. scaleC. graduated cylinderD. pencil答案：C。
中考英语科学实验的设计与实施单选题40题
中考英语科学实验的设计与实施单选题40题1.In a chemistry experiment, the main purpose of adding a certain reagent is to _.A.observe the color changeB.increase the temperatureC.reduce the pressureD.make the container heavier答案：A。
本题考查对化学实验目的的理解。
选项B“increase the temperature”增加温度通常不是添加某种试剂的主要目的。
选项C“reduce the pressure”降低压力也不是添加试剂的常见目的。
选项D“make the container heavier”让容器变重更不是添加试剂的目的。
而在化学实验中，添加试剂常常是为了观察颜色变化等现象。
2.The purpose of a physics experiment on gravity is to _.A.measure the length of an objectB.find out the speed of lightC.understand how gravity worksD.determine the shape of a molecule答案：C。
选项A“measure the length of an object”测量物体长度与重力实验目的无关。
选项B“find out the speed of light”找出光速不是重力实验的目的。
选项D“determine the shape of a molecule”确定分子形状也与重力实验不相关。
而重力实验的目的是理解重力如何起作用。
3.In a biology experiment, the purpose of using a microscope is to _.A.count the number of books in the roomB.see small organisms and structuresC.listen to musicD.calculate the area of a rectangle答案：B。
专业英语翻译 (16)
Quantum information science英文原稿:Information science and technology has penetrated into all aspects of society, in which the protagonist -- the development of computer science and technology and application, it is greatly promotes the progress of human civilization.Current computers are based on the classical physical laws, is a classical computer. Over the years, it has been recognized classic computer has some unconquerable limitations. For example, could not produce a true random number sequence, not in a limited time to simulate a conventional quantum mechanics system, not possible in acceptable time factorization of large numbers.From at present the development of microelectronics technology in light of the degree, people have to face such a problem: when the silica surface electric line of small to atomic scales, electronic circuits behavior will no longer obey the law of classical mechanics, replace sb. Is quantum mechanics. That is to say, people have to in the quantum theory under the framework of information science and information system construction.When the science is stillQuantum information (quantum information, QI) science, based on the superposition principle of quantum mechanics, based on studies of information processing a new cutting-edge science, the basic theory of modern physics and information science and technology intersect and produce a full vitality of the discipline. Quantum information science, including quantum computers, quantum state transfer from the material, quantum cryptography communication and quantum non-destructive measurement of other aspects.1980, Feynman [1] and Bennett (C. Bennett) [2] had carried out such as quantum information science theory. They pointed out that the two orthogonal polarization states of photons, atoms or atoms in two spin states, the appropriate level of these two orthogonal quantum states (for example: | 0>, | 1>) can be expressed a bit of quantum information, called quantum bit (qubit). Bit different from the classical, quantum bits in the particles (photons or atoms) not only in the | 0> or state | 1> state, and can at | 0> and | 1> of any kind of superposition state. It is this strange characteristic, so that quantum bits can not be compared with a classic bit of advantageIn the study of quantum information, in addition to quantum algorithms, quantum computers and quantum logic gates in quantum communication quantum state transfer from the material, is that people are most concerned about, the most interesting research topics, has received a preliminary experimental study the results.In addition, to explore methods of quantum information processing done by the process of quantum mechanics experiments, in turn, help people to verify and deepen understanding of the laws of the quantum world, the answer to those still remaining controversial issues. Quantum information science research, not only has important potential applications but also has far-reaching scientific significance.Powerful and efficient computational toolsIn 1985, Oxford University, more than the odd (D. Deutsch) [3] established thetheoretical basis of quantum computers, and promote the development of quantum computers. Similar to the classic computers, quantum computing, but also depends on the realization of the corresponding basic logic components - quantum logic gates (quantum logical gate, QLD). There are four possible experimental scheme of quantum logic gates, which are based on cavity quantum electrodynamics (CQED), ion trap (ion trap), nuclear magnetic resonance (NMR) and quantum dots (quantum dot).(1) cavity quantum electrodynamicsCavity quantum electrodynamics (CQED) The basic idea is that the very small number of atoms placed in a high-quality micro-cavity, the cavity electromagnetic fields (including the vacuum field) can be controlled to change, thus affecting the process of atomic radiation. CQED most successful is to study a small number of particles (photons, atoms) between theThe interaction. The method is possible to make a single photon of the electric field enhancement, so that it can make a single atom response saturation. To achieve this objective, we must achieve single-atom and single photon in the cavity of the strong coupling.As for quantum logic elements CQED quantum information processing, first by Pei Lizha in (T. Pellizzari), and others made. California Polytechnic University, Kimble (J. Kimble) group demonstrated the use of the program initial quantum logic gates. The basic approach is to capture a number of neutral atoms in the high-quality micro-optical cavity, the quantum information stored in the atoms within the state, that is the ground state of neutral atoms and on a metastable state. Contains the quantum state of a qubit is in the atomic ground state | g> and a long-lived metastable state | e> of the linear combination. The state quantum bits can be stored a long time, while the atomic energy in the cavity well with the outside world.CQED quantum logic gate is ideal to achieve one of the options. However, high-quality cavity, the connection between multiple quantum gates still have some technical difficulties.(2) ion trap technologyIon-trap quantum logic gate program first by Cirac (J. Cirac), who suggested that the current in the preliminary experiment has been achieved. In the experiment, each qubit is assigned in the capture in a linear Paul (Paul) trap single ions. Contains a qubit quantum state, is in the ion ground state | g> and a certain long-lived metastable state | e> of the linear combination. Therefore, the same atoms, it also enables qubit storage.The advantage of ion trap, ion Coulomb interaction between the far distance between the ions, so the energy of a single laser pulse tuned to a particular ion of | g> state and | e> state energy difference, we can achieve quantum information to read and change.Ion trap is the largest program in order to establish the ion trap quantum computing speed will be restricted. The reason is time - energy uncertainty relation determine the uncertainty of the laser pulse energy should be higher than the characteristic frequency of the vibration center of mass is small, the duration of each pulse should be longer than the reciprocal of the characteristic frequency; the phonon vibration frequency is generally lower the experiment the characteristic frequency of about 100 kHz, so the slower speed.In CQED, because of the role of the light field and atomic time soon, so there is no ion trap in the problems of slow response.(3) NMR techniquesNMR-based quantum computing scheme in recent years developed a new method of quantum information processing. In NMR, quantum bits are assigned certain specific molecules on the nuclear spin states. At a constant external magnetic field, each nuclear spin is either up or down. System and spin decoherence in degraded state can be kept for a longer time before, so the qubit can be stored.By a pulsed magnetic field acting on the spin-spin Rabi oscillation state to achieve the selected magnetic pulse can also be appropriate to achieve the transformation of a single magnetic spin states, because only those who are in resonance with the spin state of the external magnetic field will produce the role. Meanwhile, the spin state, there are also dipole-dipole interaction, this effect can be used to implement logic gates.NMR for quantum computation, but not as easily accepted as the first two options. Because the NMR system is "hot" nuclear spin temperature (room temperature) is generally caused by fluctuations in energy than the difference between the upper and lower levels of nuclear spin hundreds of times higher. This means that, from a single molecule in the composition of the nuclear spin quantum computer quantum state in a very large thermal noise into. The noise will drown out the quantum information. Further, the actual process is not handled a single molecule, but includes 1023 "quantum computer" macro samples.Read from this device the signal is actually a large number of molecules of the ensemble average, but the quantum algorithm is probabilistic, it comes from the randomness of quantum computing itself, and people took advantage of this randomness. Ensemble average does not mean a single unit on quantum computing. People had put forward some explanations of these difficulties, that the calculated average will not eliminate many useful quantum information. According to reports, the use of NMR methods have producedMulti-qubit logic gate, and use this to achieve a quantum state transfer from the material.Many scholars believe that the existing NMR system could not produce entanglement; arising from entanglement in quantum information is the key. NMR as a quantum information hardware will encounter many difficulties, from the principle limitations are: coherent signal and background noise ratio will be with the nuclear spin of each molecule increases the number of exponential decay. In a real system, complete with a 10-qubit NMR calculations will face serious challenges. Of course, some scholars hold different views on the above arguments, the NMR quantum logic gates to be optimistic. However, NMR will help people understand some of the nuclear spin of things.(4) quantum dotsRelated to nano-scale quantum-dot semiconductor region. These regions showed a small number of electronic states, the single-electron quantum dot can be changed into electronic state, which may be used for quantum information processing, quantum dots placed CQED they may control the materials in the spontaneous emission, enhanced light matter interaction the role. If the mature semiconductor technology combined with quantum devices, may have a practical quantum information systems. However, how toensure the purity of quantum dot materials remains a challenge.Quantum computing in an attempt to actually start, you need to try a variety of quantum logic gates program, which is a challenging work, it has only just begun. Practical quantum computing, to the number of qubits to the quantum logic gates and have made significant progress as a precondition.Magic magic- Quantum state transfer from the materialMaterial transfer from the state (teleportation) from a science fiction film, from the physical meaning of a "complete" information transfer (disembodied transport).Restrictions due to relativistic effects can not be real in an instant from one place to another place. You can achieve the object from the moment things send? Not exceed the limit in the speed of light under the premise seems to be feasible. Because, in principle, as long as all the information that constitute the object, all the quantum states can be reconstructed in any place. However, quantum mechanics tells us that, it is impossible to make accurate measurements of the quantum state can not be accurately all the information about any object. Therefore, reconstruction of this method can not be achieved, which is the quantum no-cloning theorem [4] are limited. However, another phenomenon of quantum mechanics - entanglement (EPR) of non-locality (non-local) [5] - for the realization of quantum state transfer from the material provides a new way.In 1993, six scientists from different countries, made using a combination of classical and quantum methods to achieve quantum state transfer from the object program. Using EPR (entangled state) of the non-locality, without violating the no-cloning theorem of quantum situations, can be an unknown quantum state from one place to another place. In this scheme, EPR source plays a vital role. Quantum mechanics, nonlocality violation of Bell's inequality has been confirmed by experimental results.Quantum state transfer from objects to people, not only in physics understanding and revealing the mysterious laws of nature are very important, and can be used as an information carrier quantum states, quantum state transfer is completed by a large-capacity information transmission, in principle, can achieve decipher the quantum cryptography communication, ultra-dense coding, quantum computing and quantum communication has therefore become the current rapid development of the core areas of quantum information.The protector of the secretResearch and use of password is a very ancient, wide range of issues, current password in addition to one-time password (Vernam password), but not impossible to decipher, the confidentiality of the algorithm depends on the difficulty of deciphering and calculation time. The use of quantum cryptography can guarantee from the principle Confidentiality of communications. Communication between the parties through the public channel to build their own key.Different from the classical mechanics, quantum mechanics, any time of the measurement system is a function of the system will change the system state (except in the role of operator eigenstates). Quantum cryptography can be used to encode a singlephoton polarization state. Incompatible in the two orthogonal polarization basis to measure a photon's polarization state, the result is completely random, it is impossible to get a measurement in a photon polarized in two different base in the results.Eavesdropper can not know because communication between the parties will be randomly selected each time what kind of polarization-based, so it can not accurately reproduce the signal eavesdropping, communication between the parties as long as the public than some random channel measurement results will know whether the key is eavesdropping, to discover the key insecure, you can re-establish the key until you are satisfied.Extremely accurate rulerBasic principles of quantum mechanics tells us that, due to the quantum uncertainty principle, using the general method, the measurement accuracy will eventually be shot-noise limit restrictions, it is impossible for a quantum system for unlimited precision measurements. Meanwhile, the measurement process will inevitably interfere with and affect the measured quantum state of the system, which often lead to even more accurate measurement results. The use of non-classical light field effects (ie, the unique quantum effects, there is no corresponding classical properties), the use of quantum measurement methods, can be cleverly "avoided" quantum uncertainties, and thus improve the measurement accuracy.(1) non-destructive measurement of quantumQuantum non-destructive measurement (quantum non-demolition detection, QND), 1970's by Braginski (VBBraginsky) [6] and so on, its purpose is to overcome the measurement process on the measured system caused by the interference of quantum state measurement inaccurate results, to be able to repeat the measurement without affecting the system under test is measured.QND measurement is one of the main characteristics repeatable. Measurement process must first choose a conjugate quantity of the good, the measurement process in the amount of interference on one another does not affect the amount of conjugate, and will be measured (signal field) to the probe field.In 1989 scientists from the experimental nonlinear parametric process to achieve this reaction escape, 1993 Grande Audigier (P. Grangier) through the sodium vapor-phase modulation to achieve a QND measurement. Subsequently, the national quantum optics laboratory and the use of different systems to achieve a different type of QND measurement, the transmission efficiency and the quantum state preparation ability are constantly improving. Institute of Optoelectronics, Shanxi University, 1998, the first time, the intensity difference fluctuations class QND measurement [7].(2) exceeded the limit of shot noise measurementsDue to the dominance of quantum mechanics, there is a minimum light field uncertainty, that shot noise limit. Coherent states for general light field, the shot noise limit is the amount of ups and downs two conjugate equal to the product by the uncertainty relation for the determination of limit values. Under normal circumstances, the measurement accuracy is always subject to the limit of shot noise limit, and has nothing to do with measuring instruments.Nonlinear processes of non-classical light field - state light field compression, you cankeep the product of two conjugate quantity under conditions of constant ups and downs make the ups and downs the amount of a conjugate is much smaller than the other. This means that one of the conjugate is less than the amount of ups and downs have been shot noise limit. The use of compressed light field of this feature, you can break through the measurement accuracy limit of shot noise limit, when the compression degree is 100 percent, the measurement accuracy in principle, unlimited increase.In 1987, Shaw (M. Xiao) were used with the Grand Jiyeh light field quadrature squeezed vacuum state, so that shot noise measurement sensitivity limit break. 1997 Years, Shanxi University, Institute for the direct use of optical light field intensity difference squeezing (twin beam on) for weak absorption measurements, the measurement results exceeded the signal light shot noise limit, signal to noise ratio (S / N) than the shot noise limit the signal light increased by 4 dB. In addition, there are many types of compressed light field applied in the measurement reports.Although quantum information processing with speed, capacity, safety, and the great advantages of high accuracy and a very attractive prospect, but also attracted the attention of scientists and government departments, but in addition to quantum cryptography communication may soon enter the practical stage, the quantum computer to be true, kind of away from the material sent, there is still a long way to go.One important reason is because the quantum state is "fragile." Any minor role with the external environment will lead to collapse of quantum states, namely decoherence. It must remain within a certain time quantum state from the outside world, before the collapse in the state to complete the necessary quantum computing. Although theoretically it is possible that the experimental efforts to achieve it need to do. On the other hand, quantum information processing system of storage, isolation and the accuracy of quantum logic gate operation has certain requirements, there is involved in the interaction between single photons and single atoms and other technical issues is no easy task .At present, the theoretical and experimental physicists are also working through a variety of possible ways to try to solve these problems, I believe that in the near future, quantum information science will be a breakthrough.[1] Feynman R. Int J Theor Phys, 1982,21: 4627[2] Bennett C. J Stat Phys, 1980,22: 563[3] Deutsch D. Proc Roy Soc Lond, 1985,A400: 97[4] Wootters W, et al. Nature, 1982,298: 802[5] Einstein A, et al. Phys Rev, 1935,47: 777[6] Braginsky V, et al. Usp Fiz Nauk, 1979,114: 41[7] Wang H, et al. Phys Rev Lett, 1999,82: 1414中文翻译：量子信息学信息科学与技术已经深入到社会的各个方面，其中的主角——计算机科学与技术的发展与应用，更是极大地促进了人类文明的进程。
中国英雄科研人物作文英语
中国英雄科研人物作文英语1. Fang Lizhi, a prominent astrophysicist, made significant contributions to the study of black holes and the origin of the universe.2. Tu Youyou, a Chinese pharmaceutical chemist, discovered artemisinin and dihydroartemisinin, which have saved millions of lives from malaria.3. Qian Xuesen, known as the "father of Chinese rocketry," played a crucial role in the development of China's missile and space program.4. Yuan Longping, an agronomist, developed the first high-yielding hybrid rice varieties, helping to alleviate food shortages in China and other developing countries.5. Chen-Ning Yang, a Nobel Prize-winning physicist, made groundbreaking contributions to the field of particle physics and the theory of non-abelian gauge fields.6. Wu Jianxiong, a pioneering experimental physicist, made significant contributions to the study of beta decay and the conservation of parity in weak nuclear interactions.7. Deng Jiaxian, a nuclear physicist, played a key role in China's development of nuclear weapons and nuclearenergy technology.8. Shiing-Shen Chern, a mathematician, made important contributions to differential geometry and topology, andwas a leading figure in the development of modern mathematics in China.9. Hua Luogeng, a prominent mathematician, made significant contributions to number theory and algebraic geometry, and played a key role in the development of mathematics in China.10. Wang Xuan, a computer scientist, made significant contributions to the development of computer graphics andvisualization, and played a key role in the development of computer science in China.。
消失的硬币实验英语作文
消失的硬币实验英语作文One sunny afternoon, my friends and I gathered in my backyard to conduct a fascinating experiment called "The Disappearing Coin." We were intrigued by the concept of magic tricks and wanted to explore the principles behind them. This experiment involved a simple coin and a glass of water. With our initial excitement, we couldn't wait to see the magic unfold.To properly document the experiment, we followed theformat of a scientific observation. We carefully wrote down each step, making sure not to miss any detail. Here's a detailed account of our experiment.Title: The Disappearing Coin ExperimentObjective:To investigate the optical illusion of a disappearingcoin in water and explore the scientific principles behind it.Materials:- One clear glass- One coin- WaterProcedure:1. Gather all the materials needed for the experiment.2. Fill the glass with water, making sure it is full enough to cover the coin.3. Position the glass in the center of the table.4. Place the coin on the table next to the glass.5. Before beginning the experiment, make a prediction about the outcome.6. Start the experiment by carefully picking up the coin using your thumb and forefinger.7. Slowly lower the coin into the water until it is completely submerged.8. Observe the coin through the side of the glass.9. Note any changes or illusions that occur while the coin is in the water.10. Record your observations and describe the optical illusion you observe.11. Repeat the process two more times to ensure accuracy.12. Compare and analyze the results.13. Formulate a conclusion based on your observations.Results:During the experiment, we noticed something fascinating. As the coin was lowered into the water, it appeared to change shape and position. The coin seemed to move away from us and become slightly distorted. It looked as if it was slipping out of our reach. However, when we touched the glass, werealized that the coin hadn't really moved or changed shape. It was simply an optical illusion created by the refractive properties of water.Conclusion:Through "The Disappearing Coin" experiment, we were able to explore and understand the optical illusion that occurs when a coin is submerged in water. The bending of light as it passes through the water causes the coin to appear displaced and distorted. This experiment taught us valuable lessons about the power of perception and how our senses can sometimes deceive us.By documenting and following the scientific process, we were able to conduct a successful experiment and gain a deeper understanding of the principles behind magic tricks. The Disappearing Coin Experiment served as a reminder that the world around us is full of wonders waiting to be explored and understood.。
高二年级英语心理学实验设计单选题50题
高二年级英语心理学实验设计单选题50题1. In an experiment to study the effect of sleep on memory, the amount of sleep is the _______.A. independent variableB. dependent variableC. control variableD. confounding variable答案：A。
解析：在这个研究睡眠对记忆影响的实验中，自变量是研究者主动操纵改变的变量，这里是睡眠的量。
因变量（B选项）是随着自变量的改变而发生变化的变量，在此实验中记忆才是因变量。
控制变量（（C选项）是实验中需要保持恒定不变的因素，与睡眠量无关。
混淆变量（（D选项）是可能影响实验结果，但不是研究者想要研究的变量，这里睡眠量是明确的自变量而非混淆变量。
2. A psychologist wants to see if music can reduce stress. The stress level of the participants is the _______.A. independent variableB. dependent variableC. control variableD. extraneous variable答案：B。
解析：在这个实验中，心理学家想探究音乐是否能减轻压力。
参与者的压力水平是会随着音乐（（自变量）的变化而改变的变量，所以是因变量。
自变量（A选项）应该是音乐。
控制变量（C选项）是实验中要控制保持不变的其他因素，不是压力水平。
额外变量（（D选项）是可能干扰实验结果但不是研究重点的变量，与压力水平的概念不同。
3. In an experiment about the influence of different teaching methods on students' learning efficiency, the different teaching methods are the _______.A. independent variablesB. dependent variablesC. constant variablesD. random variables答案：A。
初三英语科学研究方法选择依据单选题40题及答案
初三英语科学研究方法选择依据单选题40题及答案1. In the science lab, we conduct experiments to _____.A. have funB. get good gradesC. understand the worldD. waste time答案：C。
本题考查科学实验的目的。
选项A“have fun”玩得开心，不是科学实验的主要目的；选项B“get good grades”取得好成绩，这只是一个附带的结果，不是根本目的；选项C“understand the world”理解世界，符合科学实验的目的；选项D“waste time”浪费时间，明显错误。
2. The main purpose of scientific research is to _____.A. prove oneself rightB. find answers to questionsC. argue with othersD. show off knowledge答案：B。
科学研究的主要目的是找到问题的答案。
选项A“prove oneself right”证明自己是对的，比较片面；选项C“argue with others”和别人争论，不是科学研究的目的；选项D“show off knowledge”炫耀知识，错误。
3. When we do a scientific experiment, we should first _____.A. start doing it without thinkingB. make a planC. guess the resultD. copy others' experiments答案：B。
做科学实验时首先应该制定计划。
选项A“start doing it without thinking”不加思考就开始做，错误；选项C“guess the result”猜测结果，不是第一步；选项D“copy others' experiments”抄袭别人的实验，不可取。
紫外光辐照下CH3NH3PbI3_基钙钛矿太阳能电池失效机制
物 理 化 学 学 报Acta Phys. -Chim. Sin. 2022, 38 (5), 2007088 (1 of 11)Received: July 29, 2020; Revised: September 10, 2020; Accepted: September 11, 2020; Published online: September 16, 2020. *Correspondingauthor.Email:**************.cn;Tel.:+86-10-67396644.The project was supported by the National Key Research and Development Program of China (2016YFB0700700), the National Natural Science Foundation of China (11704015, 51621003), the Scientific Research Key Program of Beijing Municipal Commission of Education, China (KZ201310005002), and the Beijing Innovation Team Building Program, China (IDHT20190503).国家重点研究发展计划(2016YFB0700700), 国家自然科学基金(11704015, 51621003), 北京市教育委员会科研重点项目(KZ201310005002), 北京市教师队伍建设创新团队项目(IDHT20190503)资助© Editorial office of Acta Physico-Chimica Sinica[Article] doi: 10.3866/PKU.WHXB202007088 Degradation Mechanism of CH 3NH 3PbI 3-based Perovskite Solar Cells under Ultraviolet IlluminationYue Lu 1,2, Yang Ge 1,2, Manling Sui 1,2,*1 Institute of Microstructure and Property of Advanced Materials, Faculty of Materials and Manufacturing, Beijing University ofTechnology, Beijing 100124, China.2 Beijing Key Laboratory of Microstructure and Properties of Solids, Beijing University of Technology, Beijing 100124, China.Abstract: With the development of photovoltaic devices, organic-inorganic hybrid perovskite solar cells (PSCs) have been promising devices that have attracted significant attention in the fields of industrial and scientific research. Currently, the photoelectric conversion efficiency (PCE) of PSCs has been improved to 25.2%, and they are considered to be the primary alternative to silicon-based solar cells. However, the environmental stability of PSCs is unsatisfactory; they are prone to degradation under exposure to moisture, oxygen, elevated temperature, or even light illumination, which restricts their wide application in industrial production. Previous studies have elucidated that understanding the ultraviolet (UV)-induced degradation mechanism of organic-inorganic PSCs is of great importance for the improvement of light stability in PSCs. However, until now, there has been almost no comprehensive investigation on the decay process of PSCs under UV light illumination nor on the corresponding evolution of their microstructure. In this study, focused ionbeam scanning electron microscopy (FIB-SEM) and aberration-corrected transmission electron microscopy (TEM) were used to comprehensively study changes in the performance and the evolution of the microstructure of PSC devices. The experimental results show that a built-in electric field developed under UV light illumination, which drove the diffusion of iodide ions (I −) from the CH 3NH 3PbI 3 (MAPbI 3) layer to the hole transfer layer (HTL, Spiro-OMeTAD). Together with the photo-excited holes in the HTL, the I − ions reacted with the Au electrode, and the Au atoms were oxidized into Au + ions. Furthermore, Au + ions preferred to diffuse across the HTL and the perovskite layer into the interface between the SnO 2 and MAPbI 3 layers. SnO 2 is known to be a good electron transfer layer (ETL), which should collect the photo-excited electrons to reduce the Au + ions into metallic Au clusters; this is why the Au electrode was destroyed and Au clusters aggregated at the SnO 2-MAPbI 3 interface under the UV light illumination. Meanwhile, the Au clusters would accelerate the degradation of the perovskite. In addition, as the PSC performance declined (as determined by the PCE, open-circuit voltage (V oc ), and short-circuit current (J sc )), the decomposition of tetragonal MAPbI 3 into hexagonal PbI 2 was observed at the interface between Spiro-OMeTAD and MAPbI 3, along with a widening of the grain boundaries in the perovskite layer. All of these factors play critical roles in the UV-induced degradation of PSCs. This is the first study to elucidate the light-induced migration of Au from the metal electrode to the interface between SnO 2/MAPbI 3, which reveals that the UV-induced degradation of PSCs may be mitigated by finding new ways to restrain the interdiffusion of Au + and I − ions.Key Words: Perovskite solar cell; Ultraviolet; Degradation mechanism; Electron microscopy; Goldmigration紫外光辐照下CH3NH3PbI3基钙钛矿太阳能电池失效机制卢岳1,2，葛杨1,2，隋曼龄1,2,*1北京工业大学材料与制造学部，固体微结构与性能研究所，北京 1001242北京工业大学固体微结构与性能北京市重点实验室，北京 100124摘要：随着光伏产业的不断发展，有机无机杂化钙钛矿太阳能电池的研发成为科学与工业界广泛关注的焦点。
高中必修三实验英语作文
高中必修三实验英语作文1. The chemistry experiment was a real challenge for me, as I had never been good at handling chemicals andfollowing complex procedures. But I managed to stay focused and carefully measure each substance before mixing them together.2. The physics experiment, on the other hand, was more hands-on and practical. I enjoyed setting up the equipment and conducting the experiments to observe the laws of physics in action. It was fascinating to see how thetheories we learned in class could be applied in real life.3. Biology experiments were a mix of excitement and disgust for me. Dissecting a frog for the first time was a bit nerve-wracking, but I tried to stay calm and follow the instructions carefully. It was a valuable experience tolearn about the internal organs and anatomy of different organisms.4. The environmental science experiment involved collecting data from the field and analyzing the impact of human activities on the ecosystem. It was eye-opening to see the direct consequences of pollution and deforestation on the environment, and it motivated me to take action to protect our planet.5. Overall, the practical experiments in high school not only helped me understand the scientific concepts better but also improved my critical thinking and problem-solving skills. I am grateful for the hands-on learning experiences that have prepared me for future studies and career opportunities in the STEM field.。
八年级上册13个实验的实验题
八年级上册13个实验的实验题英文版In the 8th grade science curriculum, students are often required to conduct various experiments to better understand scientific concepts. In this article, we will introduce 13 experiment topics that are commonly included in the 8th grade science textbook.1. Investigating the properties of acids and bases2. Testing the effect of different types of fertilizers on plant growth3. Studying the relationship between temperature and the rate of chemical reactions4. Examining the behavior of light in different mediums5. Investigating the factors that affect the strength of an electromagnet6. Testing the conductivity of different materials7. Studying the process of photosynthesis in plants8. Exploring the principles of buoyancy by conducting experiments with different objects and liquids9. Investigating the properties of different types of soil10. Testing the effectiveness of various insulating materials11. Studying the behavior of sound waves in different environments12. Investigating the effects of different types of pollutants on water quality13. Examining the process of digestion in humans through a simulated experimentThese experiment topics cover a wide range of scientific concepts and provide students with hands-on experience in conducting experiments and analyzing data. Byengaging in these experiments, students can develop their critical thinking skills and deepen their understanding of the scientific method.英文内容的完整中文翻译在八年级科学课程中，学生经常需要进行各种实验来更好地理解科学概念。
小学上册第3次英语第4单元期中试卷(有答案)
小学上册英语第4单元期中试卷(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.We go _____ (shopping) on Saturdays.2._____ (植物文化) varies across different regions.3.The study of chemicals and their reactions is called ______.4.He likes to __________ video games.5.What is the weather phenomenon characterized by strong winds and rain?A. DroughtB. HurricaneC. EarthquakeD. Flood答案: B6.What do we call a person who studies the reactions of substances?A. ChemistB. BiologistC. PhysicistD. Mathematician答案: A7.When I visit the zoo, I always look forward to seeing this animal. I like to watch how it ______ and interacts with the other animals. Sometimes, the zookeepers give them______ to play with, which is really fun to see.8. A _______ can be a fun project for children.9.My cousin is a __________ (演员).10.We should promote _____ (可持续) gardening practices.11.The _____ (carnation) is a popular flower.12. A kitten can ______ (跳) very high.13.I can ______ (应用) my knowledge in real-life situations.14.What is the capital of Kazakhstan?A. AlmatyB. AstanaC. BishkekD. Tashkent答案: B15. A turtle can live both on ______ (陆地) and in water.16.How many legs does an insect have?A. SixB. EightC. FourD. Two答案: A17.What is the capital of Nepal?A. KathmanduB. LumbiniC. PokharaD. Bhaktapur答案: A18.We like to _____ games together. (play)19.We need to _______ (尊重) each other's opinions.20.We make _____ (sandwiches) for lunch.21.The __________ is an area characterized by specific geological features.22.We built a castle with our ____. (玩具名称)23.______ is the smallest unit of an element.24.This project is very _______ (有挑战性的).25.The bumblebee is important for _________ (授粉).26.What is the largest mammal in the ocean?A. DolphinB. SharkC. WhaleD. Octopus答案:C27.My dad likes to go ____ (camping) in the mountains.28.What is the shape of the Earth?A. SquareB. RectangleC. SphereD. Triangle答案: C29.I believe that everyone should have the right to ________ (接受教育) no matter where they live.30.My favorite ________ (游戏) is hide and seek. I always find a good ________ (藏身之处).31.The _______ (The New Deal) implemented programs to aid recovery during the Great Depression.32. collect ______ (坚果) for winter. Squirrel33.We saw an ________ at the zoo.34.The chemical formula for ammonium chloride is ______.35.The _____ (植物传播) plays a role in food production.36.Hydrogen bonds are weak attractions between _____ (polar molecules).37.The ______ (小鸡) peeps when it is hungry.38.I want to ______ a superhero. (become)39.The process of saponification produces __________ from fats and oils.40.I saw a beautiful __________ in the sky after the rain. (彩虹)41.The rabbit hops _______ (快速) away from danger.42.The first female Prime Minister of the UK was ________ (玛格丽特·撒切尔).43.The fish is swimming _____ the water. (in)44.The ancient Egyptians wrote on _______ made from papyrus. (纸)45. A windmill converts wind energy into ______.46.The shape of leaves can help identify different ______. (叶子的形状可以帮助识别不同的植物。
背部痧象特征要素数显划分方法
ｓｕｂｊｅｃｔｉｖｅ ｃｏｍｐｏｎｅｎｔｓ． Ｍｅｔｈｏｄｓ Ｆｉｒｓｔ，ｔｈｅ ｄｅｅｐ ｓｅｍａｎｔｉｃ ｓｅｇｍｅｎｔａｔｉｏｎ ａｌｇｏｒｉｔｈｍ ｍｏｄｅｌ ｗａｓ ｕｓｅｄ ｔｏ ｓｅｇｍｅｎｔ ｔｈｅ
此外，通过对痧诊的探究发现痧象可以反映人体内部
脏腑器官的变化，不同患者在刮痧时出现的痧象不
同，其痧象所表现出的面积大小、形状疏密、颜色深浅
可以反映出疾病的严重程度、病位表里等信息［１３］ 。
基于上述研究，本文希望采用一种客观的数显
用客观数显方法来对痧象的特征要素进行划分，避
方法对痧象特征进行准确识别，通过数据的方式将
ｔｒａｄｉｔｉｏｎａｌ Ｃｈｉｎｅｓｅ ｍｅｄｉｃｉｎｅ ｉｍａｇｅ ｆｅａｔｕｒｅｓ ｒｅｃｏｇｎｉｔｉｏｎ， ａｎｄ ｐｒｏｖｉｄｅｓ ｈｅｌｐ ｆｏｒ ｃｏｒｒｅｃｔｌｙ ｕｎｄｅｒｓｔａｎｄｉｎｇ ｔｈｅ
ｆｅａｔｕｒｅ ｉｎｆｏｒｍａｔｉｏｎ ｏｆ Ｓｈａ．
【 Ｋｅｙｗｏｒｄｓ】 ｔｒａｄｉｔｉｏｎａｌ Ｃｈｉｎｅｓｅ ｍｅｄｉｃｉｎｅ Ｓｈａ；ｐｒｏｍｏｔｉｏｎ ｏｆ ｉｎｆｏｒｍａｔｉｏｎ ｔｅｃｈｎｏｌｏｇｙ；ｍａｃｈｉｎｅ ｌｅａｒｎｉｎｇ；
颜色特征进行 ３ 种区间的识别；根据中医主观上对于痧象形状的划分，采用像素统计方法将痧象形状划
分为片状和点状两种。 最后，通过准确度、精确度、召回率、Ｆ１ 值对客观识别的结果进行数据上的评价。
结果 本文提出的客观数显方法在痧象颜色特征划分上的准确率达到了 ８０ ５６％，在痧象形状特征的划
最小变化法测量绝对感觉阈限实验报告 (大报告)
最小变化法测量绝对感觉阈限实验报告摘要：随机选取盐城师范学院教育学（心理方向）11届的3`名学生，使用JGW—B心理实验台操作箱，用最小变化法测定手心触压觉两点阈，学习使用最小变化法。
关键词：最小变化法感觉阈限1.引言最小变化法(The method of minimal change)是费希纳(G.T.Fechner,1860)提出测量感觉阈限的三种方法之一。
感觉阈限(sensory threshold)，又称阈限，是传统心理物理学的核心概念。
阈限可以分为两种：一为绝对阈限，指刚够引起心理感受的刺激大小；二为差别阈限，指我们刚刚能够感觉到的两个刺激（同一物理量）之间的最小差别的变化值。
最小变化法又称为极限法，最小差异法，最小可觉刺激或差别法，序列探索法。
其特点是刺激按“渐增”和“渐渐”两个序列交替变化组成，且每次变化的数量是相等的。
每一个序列的刺激强度包括足够大的范围，能够确定从一类反应到另一类反应的瞬间转换点或阈限的位置。
在用最小变化法测定感觉阈限时，通常是按物理量的强弱把刺激排成系列，相邻刺激的强度差别很小，而且刺激强度的变化应保持相等。
用最小变化法测定阈限时，有可能发生习惯误差和期望误差。
为了排除这两种误差，在递增和递减序列的实验顺序上，按“增减减增”的平衡模式进行。
2.实验方法1）被试3名在校大学生，2名女生，1名男生。
均为21岁，教育学（心理方向）专业。
2）实验仪器JGW—B心理实验台操作箱单元，两点阈测量计。
3）实验程序（1）主试事先拟好实验顺序。
刺激的两点距离从0-10毫米，渐增系列和渐减系列的起点应略有变化，并对被试保密。
（2）被试、主试先练习实验5次，被试坐在心理实验台被试位置，将左手伸入操作箱套袖式测试口，手心向上平放在测试面板上，主试用两点阈测量计的两脚沿身体纵向（即手指方向）垂直地，轻轻地（皮肤变形要小，以被试能明确感觉到触觉刺激为准）同时落在被试地手心上，并且两脚对皮肤的压力相等，被试若明确感到是两点接触皮肤，就报告“两点”，否则就报告“一点”（练习结果不记录）。
著名英文心理实验
著名英文心理实验1. Stanford Prison Experiment: This experiment was conducted in 1971 by psychologist Philip Zimbardo. It aimed to investigate the psychological effects of perceived power, focusing on the dynamics between prisoners and guards. Participants were randomly assigned roles of prisoners or guards and placed in a simulated prison environment. The study had to be terminated earlier than planned due to the extreme psychological distress experienced by the participants.2. Milgram Experiment: Conducted by psychologist Stanley Milgram in 1961, this experiment aimed to study the willingness of participants to obey authority figures, even if it meant inflicting harm on others. Participants were asked to administer electric shocks to another individual (an actor) whenever they answered questions incorrectly. The experiment revealed the surprising extent to which individuals would obey orders, even if it conflicted with their own conscience.3. Asch Conformity Experiment: This classic experiment, conducted by psychologist Solomon Asch in the 1950s, aimed to understand how social pressure influences conformity. Participants were shown a series of lines and asked to match the length of one line to the length of another. However, they were surrounded by actors who intentionally gave incorrect answers. The experiment demonstrated how individuals would often conform to the group's incorrect answer to avoid standing out.4. Little Albert Experiment: Conducted by psychologist John B. Watson and his graduate student Rosalie Rayner in 1920, the LittleAlbert experiment aimed to study classical conditioning in humans. They conditioned an 11-month-old infant (Albert) to fear a white rat by pairing its presentation with a loud noise. The study demonstrated how emotional responses could be learned through classical conditioning.5. Bobo Doll Experiment: Conducted by psychologist Albert Bandura in 1961, this experiment aimed to investigate the role of observational learning and aggression in children. Children were shown a video of an adult behaving aggressively towards a Bobo doll, and later, when given the opportunity, they imitated the aggressive behaviors. The experiment highlighted the influence of modeling and showed that children can learn aggressive behavior through observation.。
福州2024年01版小学四年级上册K卷英语第三单元期末试卷
福州2024年01版小学四年级上册英语第三单元期末试卷考试时间：100分钟（总分:100）A卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、听力题：The ________ (ball) is round and bouncy.2、填空题：My _______ (金鱼) loves to swim in circles.3、听力题：The __________ is a region known for its mountainous terrains.4、What is the capital of Chile?A. SantiagoB. Buenos AiresC. LimaD. Bogotá答案:A5、填空题：The rabbit's fur helps keep it ______ (温暖).6、听力题：A ____ is often seen climbing trees and playing with its friends.7、听力题：Chemical reactions can be classified as _____ (synthesis, decomposition, single replacement, double replacement).8、填空题：My favorite ________ (游戏) is hide and seek. I always find a good ________(藏身之处).9、What is the shape of a soccer ball?A. SquareB. TriangleC. CircleD. Rectangle10、填空题：The first successful heart surgery was performed by Dr. ______(克里斯托弗·里德教授).11、填空题：The tortoise is much ______ (慢) than the rabbit.12、填空题：The __________ was an important period of change in the United States. (冷战)13、听力题：I help my mom with _____ (清洁) the house.14、填空题：The _____ (小鸟) chirps in the trees.15、What do you call a baby chicken?A. ChickB. DucklingC. GoslingD. Poult答案:A16、What do you call a person who repairs cars?A. MechanicB. ElectricianC. PlumberD. Painter答案: A17、听力题：The cookies are ______ (fresh) out of the oven.18、填空题：An indoor garden can improve your ______ (空气质量).19、听力题：An __________ is a piece of land surrounded by water.Lions are known as the _________ of the jungle. (森林之王)21、What is the opposite of 'hot'?a. Warmb. Coolc. Coldd. Mild答案:c22、听力题：An exothermic reaction releases ______.23、填空题：My teacher is very __________ (有条理).24、听力题：The _____ (cloud/sky) is clear today.25、填空题：A ________ (冰川) moves slowly down a mountain.26、听力题：The wind is very ___ (strong/light).27、听力题：The ______ is the smallest unit of matter.28、Which month comes after January?A. FebruaryB. MarchC. AprilD. May答案:A29、填空题：The _____ (植物) has a unique shape.30、听力题：The _____ (waterfall) is beautiful.31、听力题：The chemical name for common sugar is _______.The __________ (历史的促进者) encourage scholarship.33、Which food is known for being round and cheesy?A. BreadB. PizzaC. CakeD. Soup答案:B34、填空题：The __________ is a famous city known for its ancient ruins. (罗马)35、选择题：How many colors are there in a rainbow?A. FiveB. SixC. SevenD. Eight36、听力题：Photons are particles of ________.37、ts can be trained to grow ______, creating vertical gardens. (某些植物可以被引导向上生长，形成垂直花园。
丹东2024年09版小学六年级下册T卷英语第四单元测验卷(有答案)
56、What do you call the space in which you live? A. House B. Home C. Apartment D. Dormitory 答案: B
65、How many legs does a butterfly have? A. Four B. Five C. Six D. Eight
66、填空题： My _______ (猫) sleeps in the sun.
67、听力题： A catalyst is a substance that speeds up a ______.
22、Listen and draw.(听录音，对的画笑脸，错的画哭脸。)
23、What is the capital of Comoros? A. Moroni B. Moutsamoudou C. Domoni D. Mitsamiouli 答案: A
24、听力题： In a reaction, the limiting reactant determines the amount of _____ produced.
10、What is the capital of Kenya? A. Nairobi B. Kampala C. Addis Ababa D. Dar es Salaam 答案:A. Nairobi
11、听力题： Chemical bonds can be ionic or ________.
12、填空题： The __________ (叶子) turn yellow in fall.
13、Which animal says "meow"? A. Dog B. Cat C. Cow D. Sheep 答案：B
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
the most energetic photon in an event. The peak on the mass of the η meson dominates. For final selection of ηγ events a soft cut 400 MeV < mrecγ < 620 MeV was used. The φ → KSKL background contribution is about 1 %, which was evaluated using number of events from the mrecγ interval from 620 to 840 MeV. It worth noting that number and spectrum of KSKL events are in a good agreement with Monte Carlo simulation.
The results of the fit are shown in Table 1. The detection efficiency is individual for each run because of small differences in trigger settings and in number of broken or noisy calorimeter channels. The value A describes the interference between φ meson and tails of ρ, ω resonances and with a possible anomaly contribution [7]. The results shown in Table 1 were obtained for A = 0. If the fit is performed with A as a free parameter the result coincides with the previous assumption. If A is calculated according to Ref.[7], then the results are practically the same. If standard vector dominance model is used as in the analysis of previous experiments [8], then value of σ0 decreases by only 1.5 %. We include described model uncertainty in the systematic error.
M.S.Dubrovin, I.A.Gaponenko, V.B.Golubev, V.N.Ivanchenko∗, A.A.Korol, S.V.Koshuba, I.N.Nesterenko, E.V.Pakhtusova, A.A.Polunin, E.E.Pyata, A.A.Salnikov, S.I.Serednyakov, V.V.Shary, Yu.M.Shatunov,
e+e− → φ → ηγ → 3π0γ → 7γ.
The events were selected with 6–8 photons emitted at angles of more than 27 degrees with respect to the beam and no charged particles. Standard SND cuts [5] on energymomentum balance in an event were used. As a result of such selection cosmic background is excluded and the main background process e+e− → φ → KSKL → π0π0KL is suppressed. It is seen from Fig.1, where spectrum is shown for the recoil mass mrecγ of
Averaging the data from the Table 1, one c34 ± 0.59) nb,
where the first error is a statistical one and the second is systematic. Because the results in Table 1 demonstrate some difference, the scale factor for these measurements was calculated according to PDG recommendations. It was found to be 1.5 and was taken into account in the presented statistical error. The systematic error was estimated to be 3.5 %. It is mainly determined by the the systematic uncertainty in normalization (3 %), the background subtraction error (1 %), the error in the detection efficiency estimation (0.5 %), the error in the value of the interference term (1.5 %).
where first error is a statistical one and the second is systematic. Taken into account were systematics in σ0 and in PDG data for B(φ → e+e−) (2.7 %) and B(η → 3π0) (1.2 %).
σvis(s) = σ0β(s)ε
1 − m2η/s 1 − m2η/m2φ
·
m2φ
−
Γφmφ s − imφΓφ(s)
+
A
2
,
s
=
4E2,
where E is a beam energy, σ0 – cross section in the φ-meson pole (free parameter of the fit), β(s) – radiative correction which was calculated according to Ref.[6], ε – detection efficiency, A – interference term. In the fit procedure the beam energy spread of 300 keV and the instability of average beam energy of 100 keV were taken into account. The shifts in the beam energy scale for each run were determined using the decay mode φ → KSKL [5].
arXiv:hep-ex/9809002v1 2 Sep 1998
Experimental study of the decay φ → ηγ in multi-photon final state
M.N.Achasov, S.E.Baru, A.V.Berdyugin, A.V.Bozhenok, A.D.Bukin, D.A.Bukin, S.V.Burdin, T.V.Dimova, S.I.Dolinsky, V.P.Druzhinin,
PACS: 12.39.Mk, 13.40.Hq, 14.40.Cs The φ → ηγ decay is a classical magnetic dipole transition from φ to η meson which was studied in many experiments [1]. In this work we describe the measurement of the φ → ηγ branching ratio in the SND experiment at the VEPP-2M e+e− collider in Novosibirsk. Spherical non-magnetic detector SND [2] was designed for the experimental study of e+e−-annihilation at center of mass energy about 1 GeV . Its main part is a three layer electromagnetic calorimeter consisted of 1630 NaI(Tl) crystals [3, 4]. The experiment was performed at VEPP-2M in 1996 [5]. It consists of 6 successive runs at 14 different beam energies in the region 2E0 = (980 − 1050) MeV covering the peak and close vicinity of the φ resonance. The total integrated luminosity is equal to 3.7 pb−1 which corresponds to 7.6 · 106 φ-mesons produced. The luminosity was determined using events of the two-quantum annihilation process. The following reaction was studied: