Flux Tubes of Two- and Three-Quark System in Full QCD
Monopole confinement by flux tube
1 2v2
Cµ2
+
C µ(∂µ θs
+
eAeµ)
.
(6)
We can resolve the constraint ∂µCµ = 0 by introducing an antisymmetric tensor field Bµν
and
writing
Cµ
in
the
form
Cµ
=
1 2
ǫµνρλ
∂ν
Bρλ.
introducing another auxiliary field χµν ,
DAeµ exp i
d4x
−
1 4
Fµeν
F
eµν
−
e 2
ǫµνρλ
Aeµ
∂ν
ห้องสมุดไป่ตู้
Bρλ
=
D AeµD χµν exp i
d4x
−
1 4
χµν
χµν
+
1 2
ǫµν
ρλχµν
∂ρAeλ
(2)
where the dots represent the measure for any other fields and the integrand. Here we will consider the theory in the London limit (λ → ∞ with the radial part of the field fixed), i.e. we will ignore the ρ-dependent part of the measure, and set ρ = v (constant) in the action.
Quarks——介绍夸克的英文资料-推荐下载
since in the quark model the proton has three quarks. The masses quoted are model Griffiths
dependent, and the mass of the bottom quark is quoted for two different models. But in Ch. 1
antiquark pairs (mesons) and possibly larger combinations such as the pentaquark that
could also meet the colorless condition. Quarks undergo transformations by the
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 GeV
Bottom B
1/2 -1/3
4.19 GeV(MS) 1/3 0 0 -1 0
4.67 GeV(1S)
*The masses should not be taken too seriously, because the confinement of quarks
particles.
HyperPhysics***** Quantum Physics
Up and Down Quarks
The 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 Properties and Uses of Quantum Dots
The Properties and Uses of QuantumDotsQuantum dots are small semiconductor crystals that have unique optical and electronic properties. They are nanoscale in size and can range from 2 to 20 nanometersin diameter. Quantum dots absorb and emit light at specific wavelengths, depending on their size and composition. Because of their size, they have quantum mechanical properties that differ from those of bulk materials. Quantum dots have diverse applications in areas such as biomedical imaging, solar energy, display technology, and solid-state lighting.Quantum dots have unique optical properties that make them useful in biomedical imaging. They can absorb light and emit it at a higher frequency, which makes them ideal for use in fluorescent imaging. They are also small enough to penetrate tissues and cells, allowing for high-resolution imaging of cellular structures. Moreover, quantum dots are photostable, meaning they can withstand repeated exposure to light without deteriorating, which makes them ideal for long-term imaging applications.Quantum dots have also been used in solar energy applications. Their photovoltaic properties make them ideal for use in solar cells. When exposed to sunlight, they can absorb photons and convert them into electrical energy. Because of their unique size-dependent properties, they can be tuned to absorb different wavelengths of light, making them more efficient at converting sunlight into electricity. Moreover, they are lightweight, flexible, and can be deposited onto a variety of materials, making them a promising material for use in flexible solar cells.Quantum dots also have applications in display technology. Because of their unique optical properties, they can produce highly efficient and bright colors, making them ideal for use in displays. They are also small enough to be used in ultra-thin displays, making them a promising material for use in flexible and foldable displays. Moreover, they havea longer lifespan than traditional display materials, making them ideal for use in electronic devices.Finally, quantum dots are also used in solid-state lighting applications. They can produce light at specific wavelengths, making them ideal for use in lighting applications that require high color quality and efficiency. They are also small enough to be used in LED technology, making them a promising material for use in energy-efficient lighting. Moreover, they have a longer lifespan than traditional lighting materials, making them a cost-effective and environmentally friendly option for lighting technology.In conclusion, quantum dots have unique optical and electronic properties that make them useful in a variety of applications. They can be tuned to absorb and emit light at specific wavelengths, making them ideal for use in biomedical imaging, solar energy, display technology, and solid-state lighting. Moreover, they are lightweight, flexible, and have a long lifespan, making them a promising material for the development of new technologies. With continued research and development, quantum dots have the potential to revolutionize these and other areas of technology.。
A Comprehensive Four-Quark Interpretation of D_s(2317), D_s(2457) and D_s(2632)
a r X i v :h e p -p h /0407062v 1 6 J u l 2004A Comprehensive Four-Quark Interpretation of D s (2317),D s (2457)and D s (2632)Yu-Qi Chen 1and Xue-Qian Li 21.Institute of Theoretical Physics,Chinese Academy of Sciences,100080,Beijing,China.2.Department of Physics,Nankai University,300071,Tianjin,China.Abstract The recently observed new member of the charm-strange family D s (2632)which has a surprisingly narrow width is challenging our theory.D s (2317)and D s (2457)which were observed earlier have similar behaviors and receive various theoretical explanations.Some authors use the heavy hadron chiral effective theory to evaluate heavy-light quark systems and obtain a reasonable evaluation on the masses of D s (2317)and D s (2457).An alternative picture is to interpret them as four-quark or molecular states.In this work,we are follow-ing the later and propose a unitive description for all the three new members D s (2632),D s (2317)and D s (2457)and at least,so far our picture is consistent with the data.1.Introduction Recently,the SELEX collaboration reported a new observation of a narrow resonance D s (2632)with a mass of 2632±1.6MeV /c 2and total width <17MeV [1].This resonance is the heaviest member,so far,of the charm-strange family.D s (2632)and the other two resonances D s (2317)and D s (2457),which were observed earlier[2,3,4],constitute an exotic group which is obviouslydistinguished from the ordinary D s (1968)and D ∗s (2112)by the masses,narrow total widths and decay modes.The total decay widthes of these states seem to be too small to be understoodin the regular q ¯q ′structure.If the newly observed resonances D s (2632)were of a simple quark structure of c ¯s ,one would expect that the heavier the resonance is,the shorter its lifetime should be,but the observation seems not to follow this pattern.These unusual features challenge our present theory.There have been some theoretical models proposed to interpret the structures of D s (2317)and D s (2457)which are most likely to possess spin-parity as 0+and 1+respectively [5,6].For example,Cahn and Jackson [7,8]studied the new forms of the spin-orbit and tensor forces in the heavy-light quark system and applied the technique to the D s (2317)meson.In the special models,a mass difference was predicted which is close to the experimental data.Especially,two groups independently work on the spectra by using the heavy hadron chiral effective theory[9,10].In their work,they study the heavy-light quark hadrons where the doublet [0+,1+]stands as a chiral partner of the doublet [0−,1−].Thus the mass difference between the two doublets can be accounted by the Godberg-Trieman relation and is roughly m N /3where m N is the mass of nucleon.It is consistent with the present experimental data.Instead,the authors of other theoretical papers suggested that the newly observed D s (2317)and D s (2457)are not in the simple c ¯s composition,but possibly are four-quark states,or mixtures of four-quark states and c ¯s [11,12,13].The discovery of D s(2632)which is650MeV heavier than the ground state D s,indicates that all three D s(2317)D s(2457)and D s(2632)might constitute a new group which is different from the normal members of the charm-strange family.Thus we are motivated to search for a unitive picture to describe all of the three new resonances.In this work we follow the four-quark picture and see if it canfit the data.Concretely,it is postulated that all the three resonances are four-quark states and have special spin-parity structures with narrow total widths.Since all of the resonances are isospin singlets,and possibly are four-quark states,we would determine their SU(3)quark structures according to the general principle.We stress that in this picture, we postulate that all the quarks are in S-waves.Since c¯s is an iso-singlet,thus to constitute a four quark state which is still an iso-singlet,the extra q¯q constituent must be an iso-singlet.As well known,in the SU(3)framework,an iso-singlet can have two independent components,i.e. u¯u+d¯d and s¯s.Because the orbital angular momenta for all constituents are zero,the dynamics (which is still not very clear so far)permits one of the two components to dominate in a physical resonance.We propose that in D s(2317)and D s(2457),the u¯u+d¯d component dominates, namely they are of structure c¯s(u¯u+d¯d),while for D s(2632),the s¯s component dominates,so the composition is mainly c¯s s¯s which is exactly an isospin partner of the former one.Of course, QCD dynamics allows reaction s¯s→u¯u+d¯d,which can occur by exchanging only one gluon if they are in color octet,and then might mix the two structures.But generally as the system is in a color-octet,the interaction between the quark and anti-quark is repulsive and the annihilation process is strongly suppressed by the wavefunction.Thus the mixing between the two states can be,in general,neglected.2.The D s(2317)and D s(2457)states.As proposed,D s(2317)and D s(2457)would have the quark structure c¯s(u¯u+d¯d)which guarantees the iso-singlet requirement.Generally,they can be in either(c¯s)8(u¯u+d¯d)8or (c¯s)1(u¯u+d¯d)1where the subscripts1and8refer to the color singlet and octet respectively, and may also be a mixture of the two states.With a color re-combination,the former one can be transformed into a(c¯u(¯d))1⊗(u(d)¯s)1structure,which is a DK molecule.The molecular structure was proposed to interpret some mesons such as f0(980)and a0(980)[15],several states of charmonium spectroscopy[16]andχ(3.86)[17].Here we will show that D s(2317) and D s(2457)can be accommodated in the molecular structure.Actually,D s(2317)may be a molecule of DK mesons,whereas D s(2457)is a D∗K molecule.The data support the picture of a molecular structure.The masses of D s(2317)and D s(2457) are very close and slightly below the thresholds ofM D0+M K+∼M D++M K0∼(2358∼2367)MeV,and M D∗+M K∼(2501∼2508)MeV. This is consistent with the molecular picture[15].When the mass is near the threshold,c and ¯u(¯d)quarks tend to form a D meson while u(d)and¯s quarks tend to form a K meson.The two clusters may be separated by a sizable distance.Moreover,it is noticed that the mass differences follow the relationsM D∗−M D≈M D∗s −M Ds≈M Ds(2457)−M Ds(2317)∼140MeV.(1)These relations can be understood in the molecular picture and imply that D s(2317)and D s(2457)are indeed molecular states of DK and D∗K in S-wave respectively.In a system where a heavyflavor is involved,the mass difference arises from spin-flip of the charm quarkand is suppressed by1/m c according to the heavy quark effective theory(HQET)[20].In the molecular states DK or D∗K the K-meson is pseudoscalar which is blind to the charm spin,the energy difference of D s(2317)and D s(2457)should completely come from the mass difference of D and D∗.Thus the relations(1)is nicely understood.The main decay modes of D s(2317)is D sπ.Because of the constraint of thefinal state phase space,D s(2317)→D+K is forbidden.The only available channel isD s(2317)→D+s+π0,(2) where theflavor is conserved.However,this decay mode does not conserve isospin which must be retained in the processes governed by strong interaction.A possible explanation is that the reaction is realized through D s(2317)decay into D s and a virtualη.With a virtualη−πmixing it eventually comes to D s+π[13].Certainly,this process is highly suppressed.This explains why the decay width is so narrow.For D s(2457),its main channel is D s(2457)→D∗s+π0,which is also an isospin violated process and suffers from the same suppression as for D s(2317)→D+s+π0.The experiment[4]has observed the decay channel D s(2457)→D s+γwith a small branch-ing ratio.In our picture,this process can happen via u¯u+d¯d annihilating into photons.One gluon or photon exchange between two constituent mesons is necessary to make this process possible.Therefore,the rate is small.There has also been a search for D s+ππchannel and a negative result was reported.In fact,there are several suppression effects for the process. The decay of D s(2457)which is believed as1+,into D sππor D∗sππis a P-wave reaction and moreover,it is a three-bodyfinal state process,the P-wave suppression and thefinal state phase space integration greatly reduce the decay rate.3.D s(2632).The newly observed resonance raises a challenge to the theory.In our picture,it is the SU(3) partner of D s(2317)and its peculiar narrow total width can be naturally understood.D s(2632)is supposed to be dominated by the c¯s(s¯s)structure.Since s¯s can only reside in η,η′,φ,one might suspect if D s(2632)could be a D sηmolecule,however,it is unlikely because its mass is100MeV above the threshold of D s andη.There is no suitable molecular structure which canfit this quark composition(as long as the spin-parity of D s(2632)is0+(in analog to D s(2317)).Thus we suppose that D s(2632)is a pure four-quark state.An intuitive picture of this state could be that the c quark stays in the middle and the three s quarks with gluon clouds move around it.Its mass is3m s+m c+∆E B where∆E B is the binding energy and can only be evaluated by invoking concrete models.Since constituent mass of strange quark is about150MeV heavier than the constituent mass of u and d quarks,the state of c¯s(s¯s)should be roughly300MeV heavier than c¯s(u¯u+d¯d),and this simple evaluation is consistent with the measurement.Because of the special structure,one can expect the total width of D s(2632)to be small. The reason is the Pauli exclusive principle.As well known,the destructive interference between two anti-d-quarks in D+→Kπcan remarkably reduce the total width of D±and makes its lifetime to be2.5times longer than that of D0[18,19].The same mechanism may apply here. The two anti-strange quarks in the initial state would eventually join the other quarks(c and s)to constitutefinal mesons,and an interchange of the two anti-s-quarks can result in a minus sign or in other words,a destructive interference.The most natural decay mode is D s(2632)→D sηwith the s¯s pair forming anηand c¯s forming a D s meson.With the s¯s annihilates into u¯u+d¯d pair,it can also decay to D+K. This is a higher order process,so that is suppressed.Moreover,the color matching of the quarks (anti-quarks)in the mesons leads to an additional suppression.The experimental data show that the DK decay channel is6times smaller than the D sηchannel and it is indeed understandable in our picture.4.Predictions.In this four-quark state picture,one straightforward prediction is the existence of the vector partner of D s(2632).By a simple SU(3)f manipulation,we can guess the mass of a new1+resonance D∗sj.The following relationM Ds(2632)−M Ds(2317)=M D∗sj−M Ds(2457),(3)seems to hold and we can expect the mass of D∗sj to beD∗sj≈2770MeV/c2.(4) Since it is not a molecular state(similar to D s(2632)),one cannot expect to make a precise estimate on its mass,so that if a measured mass is50MeV deviated from our predicted value, it is not surprising.D∗sj is a1+meson whose total width is small,i.e.a narrow resonance and is of quantum number of c¯s(or¯c s).Its decay modes should be dominated by D∗sηand D∗K. This narrow resonance should be tested in the near future experiments.Another interesting prediction is that these states should have decay modes to e+e−pair with the light quark pair inside the hadron annihilates into two photons with relatively large branching ratios.Specifically,we would consider D s(2632)→D∗s e+e−,D s(2317)→D∗s e+e−and D s(2457)→D s e+e−.In the normal c¯s meson,the branching ratios of these decay modes are very tiny.The measurement on these decays will be a crucial test to the four quark state explanation.5.Conclusion.In this letter,we propose a simple unitive picture for the three new members of the D s family which are observed in recent experiments.We consider D s(2317)and D s(2457)to be of c¯s(u¯u+d¯d)quark composition and moreover motivated by the data,it is supposed that the quarks(antiquarks)are re-combined into molecular ly,D s(2317)is a molecular state of DK while D s(2457)is a D∗K molecular state.By constrast,the newly observed D s(2632)is of the c¯s(s¯s)structure and it is exactly the partner of D s(2317)of0+.In this picture,we have naturally explain the narrowness of the widths of all the three resonances and discussed some decay modes.We further predict another narrow resonance which is a1+meson and its mass is located at about2770MeV with a narrow width,we also predict that these states should have relatively large branching ratios for decaying into D(∗)s and a e+e−pair.The four-quark pictures for the three states accommodate the newly observed resonances D s(2317),D s(2457)and D s(2632)and everything seems to be consistent with all existing exper-imental data.Once those predictions are confirmed by further experiments,the existence of the four quark structure can be established.Then it may open a new page in the hadronic physics.In this short note,we do not account for any concrete dynamics,but only apply the SU(3)fla-vor symmetry to analyze the quark structure of all the states D s(2317),D s(2457)and D s(2632) and try to understand their qualitative behaviors,such as the very narrow total widths and some decay modes.Since the dynamics is not involved,some details would be missing,as we discussed in last section about our prediction.It is,of course,interesting and compelling to pursue this line by adding the dynamics in the calculations.Acknowledgment:One of the authors(YQC)wishes to thank C.Liu for bringing this subject to his attention. This work is partially supported by the National Natural Science Foundation of China.References[1]A.Evdokimov et al.The SLEX Collaboration,hep-ex/0406045.[2]B.Aubert etal.The BABAR collaboration,Phys.Rev.Lett.90(2003)242001;F.Porter,hep-ex/0312019.[3]P.Krokovny et al.The BELLE collaboration,hep-ex/0308019.[4]D.Besson et al.The CLEO Collaboration,Phys.Rev.D68(2003)032002.[5]A.Pompili,hep-ph/0311036.[6]F.Porter,hep-ex/0312019.[7]R.Cahn and D.Jackson,hep-ph/0305012.[8]M.DiPierro and E.Eichten,Phys.Rev.D64(2001)114004.[9]W.A.Bardeen,E.J.Eichten and C.T.Hill,Phys.Rev.D68,054024(2003)[arXiv:hep-ph/0305049];W.A.Bardeen and C.T.Hill,Phys.Rev.D49,409(1994)[arXiv:hep-ph/9304265].[10]M.A.Nowak,M.Rho and I.Zahed,Phys.Rev.D48,4370(1993)[arXiv:hep-ph/9209272];M.A.Nowak,M.Rho and I.Zahed,arXiv:hep-ph/0307102.[11]T.Barnes,F.Close and H.Lipkin,hep-ph/0305025;A.Szczepaniak,hep-ph/0305060.[12]E.Beveren and G.Rupp,hep-ph/0305035.[13]H.Cheng and W.Hou,hep-ph/0305038.[14]H.Georgi,Lie Algebra in Particle Physics,Benjamin/Cummings Pub.Co.1982,New York.[15]J.Weinstein and N.Isgur,Phys.Rev.D41(1990)2236.[16]A.Rujula,H.Georgi and S.Glashow,Phys.Rev.Lett.38(1977)317.[17]S.F.Tuan,Phys.Lett.bf B473(2000)136.[18]I.Bigi,B.Blok,M.Shifman,N.Uraltsev and A.Vainstein,in B decays,edited by S.Stone,World Scientific Pub.Co.1994.[19]W.Dai,X.He,X.Li and G.Zhao,Phys.Rev.D60(1999)034005.[20]N.Isgur and M.Wise,Phys.Lett.B232(1989)113;237(1980)527.。
超导量子电路中微波相干效应的研究
超导量子电路中微波相干效应的研究摘要量子相干和干涉效应是量子光学和激光物理中非常重要的课题之一，基于相干效应的许多新颖的量子现象已经得到了研究学者的深入研究。
另一方面，超导量子电路，又称人工原子，近年来在量子信息和计算方面得到了广泛的应用。
超导量子比特是一种固态装置，不仅易于设计性，而且有很好的参数可控性和实验制备性。
因此，各种各样的超导比特已得到了精确制备和广泛应用，而且，许多量子光学现象可以在超导量子电路系统中得以验证，在量子光学领域有着重要的研究和应用价值。
本文中，我们主要研究微波驱动的三能级∆型超导fluxonium 比特电路系统的量子相干效应。
通过选择合适的参数展现系统的量子光学特性，进而分析系统的特征和量子现象的物理机制。
研究内容如下：(1) 我们研究了三能级∆型超导fluxonium电路系统中的色散转换特性。
当用三个微波场分别耦合于三能级超导fluxonium电路的三个不同的跃迁时，超导电路系统的吸收和色散谱强烈依赖于外场的相对相位和强度。
当相对相位π/2 改变到3π/2时，正负色散发生转换，此时，吸收为零。
正负色散转换对光的超慢与超快传播方面有着重要的应用。
而且，当我们固定相对相位时，通过通过调节经典场的相对强度也可以获得无吸收的色散开关。
(2) 我们研究了三能级∆型超导fluxonium电路系统中的相干布居捕获现象。
考虑三个外加场应用于不同跃迁的物理模型，结果表明系统的相干布居捕获效应强烈地依赖外加场的相对相位和强度。
当相对相位为0或π时，最大的原子相干获得，相干布居捕获发生。
但是当相对相位为π/2时，原子的相干性减弱。
此外，当固定相对相位为π/2并增强两个低能级间的Rabi频率时，相干性减小。
我们利用缀饰态方法解释相对相位及强度对布居捕获调制的物理机制。
总之，利用外加微波场与超导fluxonium电路系统的相互作用，依赖于外加场相位和强度的色散开关和相干布居捕获效应发生。
这里我们应用了超导量子电路这个易操控的固态系统，而且采用的是可行性的实验参数。
Single-flavor CSL phase in compact stars
Three-body relativistic flux tube model from QCD Wilson-loop approach
2
Quark-antiquark flux tube model
In QCD the quark-antiquark gauge invariant propagator can be written G(x1 , x2 , y1, y2 ) = 1 c c = 0|Tψ2 (x2 )U (x2 , x1 )ψ1 (x1 )ψ 1 (y1 )U (y1 , y2 )ψ2 (y2 )|0 = 3 1 F F = Tr U (x2 , x1 )S1 (x1 , y1 |A)U (y1 , y2 )C −1 S2 (y2 , x2 |A)C . 3
(1)
Here c denotes the charge-conjugate fields, C is the charge-conjugation matrix, U the path-ordered gauge string U (b, a) = P exp ig 1
b
a
dxµ Aµ (x) ,
CERN-TH/95-194 IFUM 511/FT
Three-body relativistic flux tube model from QCD Wilson-loop approach
arXiv:hep-ph/9507300v1 13 Jul 1995
N. Brambilla, G.M. Prosperi
CERN-TH/95-194 IFUM 511/FT July 1995
Preprint submitted to Elsevier Preprint
1 February 2008
1
Introductiห้องสมุดไป่ตู้n
In a recent paper we have shown that, for the quark-antiquark system, neglecting spin-dependent terms, it is possible to derive rigorously the so-called relativistic flux tube model from the Wilson area law in QCD. To achieve the result, the essential ingredients were the path-integral representation of the Pauli-type propagator we used in the derivation of the semirelativistic potential, the replacement of the 1/m2 expansion of the purely kinetic terms by their closed form and the explicit integration over the momenta of the functional integral. In this letter we want to show how a similar result can be worked out for the three-quark system starting from the corresponding representation for the three-quark propagator we have considered in ref. [1]. The resulting Lagrangian turns out to correspond to a star flux tube configuration. As in the quark-antiquark case, the Hamiltonian can be expressed only in the form of an expansion in 1/m2 or in the string tension σ . In the first situation we obtain the Wilson loop semirelativistic potential, but for the spin-dependent part. In the second one we end up with a very complicated result which, however, reduces to the three-quark string model already considered in the literature for low angular momentum. In Section 2 we review the quark-antiquark case to clarify the procedure and to establish notation; in Sec. 3 we derive the new Lagrangian and in Sec. 4 we obtain the Hamiltonian of the resulting model.
High Frequency Dynamics and Third Cumulant of Quantum Noise
a r X i v :0807.0252v 1 [c o n d -m a t .m e s -h a l l ] 1 J u l 2008High Frequency Dynamics and Third Cumulant ofQuantum NoiseJ.Gabelli and B.ReuletLaboratoire de Physique des Solides,UMR8502bˆa timent 510,Universit´e Paris-Sud 91405ORSAY Cedex,FrancePhysics of current fluctuations has proven,during the last 15years,to be a very profound topic of electron transport in mesoscopic conductors (for a review,see ref.[1]).Usually,current fluctuations are characterized by their spectral density S 2(ω)measured at frequency ω:S 2(ω)= i (ω)i (−ω) ,(1)where i (ω)is the Fourier component of the classical fluctuating current at frequency ωand the brackets . denote time averaging.In the limit where the current can be considered as carried by individual,uncorrelated electrons of charge e crossing the sample (as in a tunnel junction),S 2(ω)is given by the Poisson value S 2(ω)=e I and is independent of the measurement frequency ω.At sufficiently high frequencies,however,this relation breaks down and should reveal information about energy scales of the system.In particular,in the quantum regime ω>eV (V is the voltage across the conductor),it turns out that the noise cannot be seen as a charge counting statistics problem anymore even for a conductor without intrinsic energy scale.In this regime,the noise spectral density reduces to its equilibrium value determined,at zero temperature,by the zero-point fluctuations (ZPF):S (eq )2(ω)=G ω,(2)with G the conductance of the system.Experimental investigations of the shot noise at finite frequency have clearly shown a constant (voltage independent)noise spectral density for ω>eV in several systems [2,3,4].Although these experiments were not able to give an absolute value of the equilibrium noise (because of intrinsic noise of linear amplifiers used for the measurement),one has good reasons be believe that ZPF can be observed with this kind of amplifiers.Indeed,it as been proven in other detection schemes,theoretically [5,6]and experimentally [7,8,9,10],that ZPF can be detected from deexcitation of an active detector whereas they cannot be detected by a passive detector which is itself effectively in the ground state.In view of recent interest in the theory of the full counting statistics (FCS)of charge transfer,attention has shifted from the conventional noise (the variance of the current fluctuations)to the study of the higher cumulants of current fluctuations.Whereas the discrimination between active and passive detector seems to be clear for noise spectral density measurement,the situation is more complex for the measurement of high order cumulants at finite frequency.Indeed,the issues of detection scheme are closely related to the problem of ordering quantum current operators and,if the problem can be solved in a general wayfor two operators [6,11],measurements of higher cumulants are pointing out the problem of appropriate symmetrization of the product of n current operators:S n (ω)= i (ω1)i (ω2)...i (ωn ) δ(ω1+ω2+...+ωn )(3)It is the goal of this paper to clearly present the problem of the third cumulant measurement on a well defined experimental setup using a linear amplifier as a detector.Until now,measurements of the third cumulant S 3of voltage fluctuations have been performed at low frequency,i.e.in the classical regime ω<eV,k B T where voltage fluctuations arise from charge transfer process [12,13,14].We report here the first measurement of S 3at high frequency,in the quantum regime ω>eV,k B T .It raises central questions of the statistics of quantum noise,in particular:1.The electromagnetic environment of the sample has been proven to strongly influence the measure-ment,through the possible modulation of the noise of the sample[12].What happens to this mechanism in the quantum regime?2.For eV< ω,the noise is due to ZPF and keeps its equilibrium value:S2=G ωwith G theconductance of the sample.Therefore,S2is independent of the bias voltage and no photon is emitted by the conductor.Is it possible,as suggested by some theories[15,16,17],that S3=0in this regime?In the spirit of these questions,we give theoretical and experimental answers to the environmental effects showing that they involve dynamics of the quantum noise.We study the case of a tunnel junction, the simplest coherent ing these results,we investigate the question of the third cumulant of quantum noise.1Environmental Effects and Dynamics of Quantum NoiseWe show in this section that the noise dynamics is a central concept in the understanding of environmen-tal effects on quantum transport.First,we present a simple approach(in the zero frequency limit)to calculate the effects of the environment on noise measurements in terms of the modification of probability distribution P(i)of currentfluctuations.We do not provide a rigorous calculation,but simple consider-ations that bear the essential ingredients of the phenomenon.This allows us to introduce the concept of noise dynamics and determine the correct current correlator which describes it at any frequency.Then, we report thefirst measurement of the dynamics of quantum noise in a tunnel junction.We observe that the noise of the tunnel junction responds in phase with the ac excitation,but its response is not adiabatic, as obtained in the limit of slow excitation.Our data are in quantitative agreement with a calculation we have performed.Figure1:Schematics of the experimental setup.Currentfluctuations i(t)=I(t)− I are measured by an ampmeter with a bandwidth∆f.1.1Effects of the environment on the probability distribution P(i)In the zero-frequency limit,high order moments are simply given by the probability distribution of the current P(i)calculated from the currentfluctuations measured in a certain bandwidth∆f(seefig.1):M n= i n P(i)di(4) The cumulant of order n,S n is then given by a linear combination of M k∆f k−1,with k≤n[18].In practice,it is very hard to perfectly voltage-bias a sample at any frequency and one has to deal with the non-zero impedance of the environment Z(see Fig.1).If Vfluctuates,the probability P(i)is modified.Let us call P(i;V)the probability distribution of the currentfluctuations around the dc current I when the sample is perfectly biased at voltage V,and P(i)the probability distribution in the presence of an environment.R is the resistance of the sample,taken to be independent of V.If the sample is biased by a voltage V0through an impedance Z,the dc voltage across the sample is V=R /Z V0with R =RZ/(R+Z).The currentfluctuations in the sampleflowing through the external impedance induce voltagefluctuations across the sample,given by:δV(t)=− +∞−∞Z(ω)i(ω)e iωt dω(5)Consequently,the probability distribution of thefluctuations is modified.This can be taken into account if thefluctuations are slow enough that the distribution P(i)follows the voltagefluctuations.Under this assumption one has:P(i)=P(i;V+δV)≃P(i,V)+δV∂P+ (7)∂VThis equation,derived in Ref.[19],shows that environmental correction to the moment of order n is related to the next moment of the sample perfectly voltage biased.For n=1we recover the link between noise and Dynamical Coulomb Blockade through the noise susceptibility(see below)that appears as ∂M2/∂V in the simple picture depicted here[20].Let us now apply the previous relation to the third cumulant(S n=M n∆f n−1for n=2,3):S3≃S3−3Z S4∂V(8)It is a simplified version of the relation derived in refs.[21].The way to understand this formula is the following:thefirst term on the right is the intrinsic cumulant;the second term comes from the sample currentfluctuations i(t)inducing voltagefluctuations across itself.These modulate the sample noise S2 by a quantity−Zi(t)dS2/dV.This modulation is in phase with thefluctuating current i(t),and gives rise to a contribution to the third order correlator i3(t) .This environmental contribution involves the impedance of the environment and the dynamical response of the noise which,in the adiabatic limit considered here,is given by dS2/dV.However,at high enough frequencies,and in particular in the quantum regime ω>eV,this relation should be modified to include photo-assisted processes.The notion of dynamical response of the noise is extended in the following section to the quantum regime in order to subtract properly the environmental terms in the measurement of the third cumulant.1.2Dynamics of Quantum Noise in a Tunnel Junction under ac Excitation In the same way as the complex ac conductance G(ω0)of a system measures the dynamical response of the average current to a small voltage excitation at frequencyω0,we investigate the dynamical response of (ω),that we name noise susceptibility.It measures the in-phase and out-of-phase currentfluctuationsχωoscillations at frequencyω0of the current noise spectral density S2(ω)measured at frequencyω.In order to introduce the correlator that describes the noise dynamics,we start with those which describe noise and photo-assisted noise.Beside the theoretical expressions,we present the corresponding measurements on a tunnel junction[22].It allows to calibrate the experimental setup and give quantitative comparisons between experiment and theory.Noise and photo-assisted noiseThe spectral density of the currentfluctuations at frequencyωof a tunnel junction(i.e.with no internal dynamics)biased at a dc voltage V is[1]:S02(ω+)+S02(ω−)S2(V,ω)=d S 2(ω)/d V ä (R 0/2e )-60-40-200204060eV/k B TS 2/(4k B G ) (K )Figure 2:Top:Measured noise temperature T N =S 2(ω)/(4k B G )of the sample plus the amplifier with no ac excitation.Bottom:measured differential noise spectral density dS 2(ω)/dV for various levels of excitation z =eδV/( ω0).z =0corresponds to photo-assisted noise.Solid lines are fits with Eq.(10).where ω±=ω±eV/ .S 02(ω)is the Johnson-Nyquist equilibrium noise,S 02(ω)=2G ωcoth ( ω/(2k B T ))and G is the conductance.At low temperature,the S 2vs.V curve (obtained at point C on Fig.3)has kinks at eV =± ω,as clearly demonstrated in our measurement,see Fig.2top.The temperature of the electrons is obtained by fitting the data with Eq.9.We obtain T =35mK,so that ω/k B T ∼8.5.Note that a huge,voltage independent,contribution T N ∼67K is added to the voltage dependent noise coming from the sample which masks the contribution from the ZPF.When an ac bias voltage δV cos ω0t is superimposed on the dc one,the electrons wavefunctions acquire an extra factor n J n (z )exp(inω0t )where J n is the Bessel function of the first kind and z =eδV/( ω0).The noise at frequency ωis modified by the ac bias,to give:S pa 2(V,ω)=+∞ n =−∞J 2n (z )S 2(V −n ω0/e,ω)(10)This effect,called photo-assisted noise,has been measured for ω=0[2].We show below the first measurement of photo-assisted noise at finite frequency ω.The multiple steps separated by eV = ω0are well pronounced and a fit with Eq.10provides the value of the rf coupling between the excitation line and the sample δV (see Fig.2bottom).Noise susceptibilityPhoto-assisted noise corresponds to the noise S 2(ω)in the presence of an excitation at frequency ω0,obtained by time averaging the square of the current filtered around ω,as in [2]for ω=0and in[4]for ω∼ω0.This is similar to the photo-voltaic effect for the dc current.The equivalent of the dynamical response of current at arbitrary frequencies ω0is the dynamical response of noise at frequency ω0.It involves the beating of two Fourier components of the current separated by ±ω0expressed by the correlator i (ω)i (ω0−ω) .Using the techniques described in [1],we have calculated the correlator that corresponds to our experimental setup,using the ”usual rules”of symmetrization for a two currentFigure3:Experimental setup for the measurement of the noise dynamics X(ω0,ω)and the third cumulant S3(ω,ω0−ω)forω∼ω0.The symbol⊕represents a combiner,which output is the sum of its two inputs. The symbol⊗represents a multiplier,which output is the product of its two inputs.The diode symbol represents a square law detector,which output is proportional to the low frequency part of the square of its input.correlator and a classical detector.Wefind the dynamical response of noise for a tunnel junction[20]:1X(ω0,ω)=(12)δVχω(ω)expresses the effect,tofirst order inδV,of a small excitation at frequencyω0to the noise measured 0at frequencyω.We show in Fig.4the data for X(ω0,ω)/δV at small injected powers as well as the (ω=ω0):theoretical curve forχωeχω(ω)=χω(0)=All the data fall on the same curve,as predicted,and are very well fitted by the theory.The cross-over occurs now for eV ∼ ω.χω(ω)is clearly different from the adiabatic response of noise dS 2(ω)/dV (solid line in Fig.4).However,in the limit δV →0and ω0→0(with z ≪1),Eq.(13)reduces to χω(0)∼(1/2)(dS 2/dV ).The factor 1/2comes from the fact that the sum of frequencies,±(ω+ω0)(here ∼12GHz),is not detected in our setup.This is the central result of our work:the quantum noise responds in phase but non-adiabatically.-1.0-0.50.00.51.0χω(ω) ä (R 0/e ) -30-20-100102030eV/k B TFigure 4:Normalized noise susceptibility χω(ω)vs.normalized dc bias.Symbols:data for various levels of excitation (z =0.85,0.6and 0.42).Dotted and dashed lines:fits of χω(ω)(Eq.(13)).Solid line:(1/2)dS 2/dV (experimental),as a comparison.Inset :Nyquist representation of X (ω0,ω)for z =1.7(in arbitrary units).The in-phase and out-of-phase responses are measured by shifting the phase ϕof the reference signal by 90◦.2Third Cumulant of Quantum Noise Fluctuations 2.1Operator oderingA theoretical framework to analyze FCS was developed in Ref.[23]to evaluate any cumulant of the current operator in the zero-frequency limit.In order to analyze frequency dispersion of current fluctuations it is necessary to go beyond the usual FCS theory [15,16,17].An essential problem in these approaches is to know what ordering of current operators ˆi corresponds to a given detection scheme.This problem is simpler for S 2:the correlator S +(ω)= ˆi (ω)ˆi (−ω) with ω>0represents what is measured by a detector that absorbs the photons emitted by the sample,like a photo-multiplier.The correlator S −(ω)= ˆi (−ω)ˆi (ω) =S +(−ω)represents what the sample absorbs,and can be detected by a detector in an excited state that decays by emitting photons into the sample.Finally a classical detector cannot separate emission from absorptions,and measures the symmetrized quantity:S sym.2(ω)= ˆi (ω)ˆi (−ω) + ˆi (−ω)ˆi (ω)2.2Measurement of S v 3(ω,0)Experimental setupWe have investigated the third cumulant S v 3(ω,0)of the voltage fluctuations of a tunnel junction in the quantum regime ω>eV .For technical reasons (the input impedance of the rf amplifier is fixed at Z =50Ω),we measured voltage fluctuations v (t )instead of current fluctuations i (t ).Thus,the impedance R =RZ/(R +Z )will act as the environment and will affect the measurement of the third cumulant S 3(ω,0)of the current fluctuations.We use the same experimental setup and sample as for the noisedynamics measurement,the only change is that the ac excitation is switched off:δV =V 0=0(see Fig.3.Thus only the noise of the amplifier can modulate the noise of the sample.A 5.7−6.7GHz band-pass filter followed by a square law detector allows to mix high-frequency components v (ω)v (−ω−δω)which are multiplied by low-frequency components selected by a 200MHz low pass filter,we end up with a dc signal proportional to S V 3∝ v (ω)v (−ω−δω)v (δω) .The fact that the same setup is used to detected S 3and χis quite remarkable:it clearly indicates that the environmental effects in S 3are indeed described by χand not by dS 2/dV .S v 3 (e 2R D 3 µΑ)eV/k B T S 3/e 2(µA )eV/k B T (a)(b)Figure 5:(a)Measurement of S v 3(ω,0)vs.bias voltage V (circles).The solid line corresponds to the best fit with Eq.(15).The dash dotted line corresponds to the perfect bias voltage contribution and the dotted lines to the effect of the environment.(b)Measurement of S 3(ω,0)vs.bias voltage V (squares).Experimental resultsS v3at T=35mK is shown in Fig.5(a),these data were averaged for4days.These results are clearly different from the voltage bias result because of the environmental contributions.As described before (see section1),the noise of the sample is modulated by its own noise and by the noise of the amplifier S2,N,to give rise to an extra contribution to S v3.By generalizing the expression(8),wefind,assuming real,frequency independent impedances to simplify the expression(but we used the full expression for thefits of the data):S v3(ω,0)=−R3S3(ω,0)+R4(S2,N(0)+S2(0))χ0(ω)++R4(S2,N(ω)+S2(ω))χω(0)+R4(S2,N(ω)+S2(ω))χω(ω)(15)To properly extract the environmental effects,wefit the data obtained at different temperatures(35mK, 250mK,500mK,1K,4.2K).The parameters R (0),R (ω),S2,N(0)and S2,N(0)that characterize the environment are independent of temperature,whereas S2(V)andχ(V)have temperature dependent shapes.This allows for a relatively reliable determination of the environmental contribution.We have performed independent measurements of these parameters and obtained a reasonable agreement with the values deduced from thefit.However more experiments are needed with another,more controlled environment,to confirm our result.The intrinsic S3in the quantum regime,obtained after subtraction of the environmental contributions,is shown in Fig.5(b).It seems to confirm the theoretical prediction by[16,17](solide line),i.e.S3(ω,0)=e2I even for ω>eV.Figure6:(a)Experimental detection scheme.The symbol represents a multiplier,which output is the product of its two inputs.The diode symbol represents a square law detector,which output is proportional to the low frequency part of the square of its input.S3(ω,δω→0)is given by the product of the square of high frequencyfluctuations with low frequencyfluctuations.(b)Equivalent detection scheme using a photodetector to measure square of high frequencyfluctuations.3ConclusionWe have shown thefirst measurement of the noise susceptibility,in a tunnel junction in the quantum regime ω∼ ω0≫k B T(ω/2π∼6GHz and T∼35mK)[4].We have observed that the noise responds in phase with the excitation,but not adiabatically.Our results are in very good,quantitative agreement with our prediction based on a new current-current correlatorχω(ω)∝ i(ω)i(ω0−ω) .Using the fact that the environmental contributions to S3are driven byχ,we have been able to extract the intrinsiccontribution from a measurement of v3 on a tunnel junction in the quantum regime.Our experimental setup is based on a”classical”detection scheme using linear amplifiers(see Fig.6(a))and the results are in agreement with theoretical predictions:S3(ω,0)remains proportional to the average current and is frequency independent[16,17].This result raises the intriguing question of the possibility to measure a non-zero third cumulant in the quantum regime ω>eV whereas the noise S2(ω)is the same as at equilibrium,and given by the zero-pointfluctuations.One can think of another way to measure S3(ω,0)with a photodetector(sensitive to photons emitted by the sample),as depicted infig.6(b).In this case S3is the result of correlations between the low frequency currentfluctuations and the low frequencyfluctuations of theflux of photons of frequency ωemitted by the sample.Since no photon of frequencyωis emitted for eV< ω,the output of the photo-detector is zero and S3(ω,0)=0.The expectation of such a measurement is sketched by a dashed line infig.5(b).Note that such a detection scheme has already been applied on laser diodes[24,25]. AcknowledgementsWe are very grateful to L.Spietz for providing us with the sample that he fabricated at Yale University. 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Flavor asymmetry of the nucleon sea in an unquenched quark model
a r X i v :0809.2299v 1 [n u c l -t h ] 12 S e p 2008EPJ manuscript No.(will be inserted by the editor)Flavor asymmetry of the nucleon sea in an unquenched quark modelRoelof Bijker 1and Elena Santopinto 21ICN-UNAM,AP 70-543,04510Mexico DF,Mexico2INFN,Sezione di Genova,via Dodecaneso 33,16164Genova,ItalyReceived:date /Revised version:dateAbstract.We discuss the flavor asymmetry of the nucleon sea in an unquenched quark model for baryonsin which the effects of quark-antiquark pairs (u ¯u ,d ¯d and s ¯s )are taken into account in an explicit form.Itis shown that the inclusion of q ¯q pairs leads to an excess of ¯d over ¯u quarks in the proton.PACS.14.20.Dh Protons and neutrons –12.39.-x Phenomenological quark models –11.30.Hv Flavorsymmetries –11.55.Hx Sum rules1IntroductionThe flavor content of the nucleon sea provides an impor-tant test for models of nucleon structure.A flavor sym-metric sea leads to the Gottfried sum rule S G =1/3[1],whereas any deviation from this value is an indication ofthe ¯d/¯u asymmetry of the nucleon sea.The first clear evidence of a violation of the Gottfried sum rule came from the New Muon Collaboration (NMC)[2],which was later confirmed by Drell-Yan experiments [3]and a mea-surement of semi-inclusive deep-inelastic scattering [4].Allexperiments show evidence that there are more ¯dquarks in the proton than there are ¯u quarks.The experimental studies and theoretical ideas on the flavor asymmetric sea are summarized in several review articles [5].In the constituent quark model (CQM),the proton is described in terms of a uud valence-quark configuration.Therefore,the violation of the Gottfried sum rule implies the existence of higher Fock components (such as uud −q ¯q configurations)in the proton wave function.Additional indications for the importance of multiquark components are provided by parity-violating electron scattering ex-periments,which have shown evidence for a nonvanish-ing strange quark contribution,albeit small,to the charge and magnetization distributions of the proton [6],and by CQM studies of baryon spectroscopy [7].Theoretically,the role of q 4¯q configurations in the nu-cleon wave function was studied in an application to the electromagnetic form factors [8].Mesonic contributions to the spin and flavor structure of the nucleon are reviewed in [5].In another,CQM based,approach the importance of s ¯s pairs in the proton was studied in a flux-tube break-ing model based on valence-quark plus glue dominance to which s ¯s pairs are added in perturbation [9].The pair-creation mechanism is inserted at the quark level and the one-loop diagrams are calculated by summing over a com-Fig.1.One-loop diagram at the quark levelplete set of intermediate baryon-meson states BC (see Fig.1).The pairs are created with the 3P 0quantum num-bers of the vacuum.For consistency with the OZI-rule and to retain the success of the CQM in hadron spectroscopy,it was found necessary to sum over a complete set of in-termediate states,including both pseudoscalar and vector mesons,rather than just a few low-lying states [9,10].In order to address the violation of the Gottfried sum rule,we have generalized the model of [9]to include u ¯u and d ¯d loops as well.The formalism of the ensuing un-quenched quark model is described in a separate contribu-tion to these proceedings [11].The aim of this manuscript is to discuss an application to the flavor asymmetry of the nucleon sea.2Flavor asymmetryThe first clear evidence for the flavor asymmetry of the nu-cleon sea was provided by NMC at CERN [2].The flavor asymmetry is related to the Gottfried integral for the dif-2Roelof Bijker,Elena Santopinto:Flavor asymmetry of the nucleon sea in an unquenched quark model Table1.Experimental values of the Gottfried integralNMC40.004<x<0.800.2281±0.0065HERMES2.30.020<x<0.300.23±0.02E866/NuSea540.015<x<0.350.255±0.008x=131dx ¯d(x)−¯u(x) .Under the assumption of aflavor symmetric sea¯d(x)=¯u(x)one obtains the Gottfried sum rule S G=1/3.The final NMC value is0.2281±0.0065at Q2=4(GeV/c)2 for the Gottfried integral over the range0.004≤x≤0.8 [2],which implies aflavor asymmetric sea.The violation of the Gottfried sum rule has been confirmed by other exper-imental collaborations[3,4].Table1shows that the exper-imental values of the Gottfried integral are consistent with each other within the quoted uncertainties,even though the experiments were performed at very different scales, as reflected in the average Q2values.Theoretically,it was shown that in the framework of the cloudy bag model the coupling of the proton to the pion cloud provides a mecha-nism to produce aflavor asymmetry due to the dominance of nπ+among the virtual configurations[12].In the unquenched quark model,theflavor asymmetry can be calculated from the difference of the number of¯d and¯u sea quarks in the protonN¯d−N¯u= 10dx ¯d(x)−¯u(x) .Even in absence of explicit information on the(anti)quark distribution functions,the integrated value can be ob-tained directly from the left-hand side of Eq.(1).The effect of the quark-antiquark pairs on the Gottfried inte-gral is a reduction of about one third with respect to the Gottfried sum rule,corresponding to an excess of¯d over ¯u quarks in the proton which is in qualitative agreement with the NMC result.It is important to note that in this calculation the parameters were taken from the literature [9,13],and that no attempt was made to optimize their values.Due to isospin symmetry,the neutron has a similar excess of¯u over¯d quarks.3Summary,conclusions and outlookIn this contribution,we discussed the importance of quark-antiquark pairs in baryon spectroscopy.The calculations were carried out in an unquenched quark model for baryons in which the contributions from u¯u,d¯d and s¯s loops are taken into account in a systematic way[11].The model was applied to theflavor asymmetry of the nucleon sea.In afirst,exploratory,calculation in which the parameters were taken from the literature[9,13],it was shown that the inclusion of q¯q pairs leads immedi-ately to an excess of¯d over¯u quarks in the proton.We emphasize again that no attempt was made to optimize the parameters in the calculations.In our opinion thefirst results for theflavor asymme-try(discussed here)and the proton spin(see[11])are very promising and encouraging.We believe that the inclusion of the effects of quark-antiquark pairs in a general and consistent way,as suggested in[11]and in this contribu-tion,may provide a major improvement to the constituent quark model,increasing considerably its range and appli-cability.In future work,the unquenched quark model will be applied systematically to several problems in light baryon spectroscopy,such as the electromagnetic and strong cou-plings,the elastic and transition form factors of baryon resonances,their sea quark content and theirflavor de-composition[14].AcknowledgmentsThis work was supported in part by a grant from CONA-CYT,Mexico and in part by INFN,Italy. References1.K.Gottfried,Phys.Rev.Lett.18,1174(1967).2.P.Amaudruz et al.,Phys.Rev.Lett.66,2712(1991);M.Arneodo et al.,Nucl.Phys.B487,3(1997).3. A.Baldit et al.,Phys.Lett.B332,244(1994);R.S.Towell et al.,Phys.Rev.D64,052002(2001).4.K.Ackerstaffet al.,Phys.Rev.Lett.81,5519(1998).5.S.Kumano,Phys.Rep.303,183(1998);J.Speth and A.W.Thomas,Adv.Nucl.Phys.24,83 (1998);G.T.Garvey and J.-C.Peng,Prog.Part.Nucl.Phys.47,203(2001).6. A.Acha et al.,Phys.Rev.Lett.98,032301(2007).7.See e.g.N∗Physics,Proceedings of the Fourth CE-BAF/INT Workshop,Eds.T.-S.H.Lee and W.Roberts (World Scientific,1997);N.Isgur,Nucl.Phys.A623,37c(1997);R.Bijker,F.Iachello and A.Leviatan,Phys.Rev.D55, 2862(1997);M.Aiello,M.M.Giannini and E.Santopinto,J.Phys.G: Nucl.Part.Phys.24,753(1998);L.Ya.Glozman,W.Plessas,K.Varga and R.F.Wagen-brunn,Phys.Rev.D58,094030(1998);R.Bijker,F.Iachello and A.Leviatan,Ann.Phys.(N.Y.) 284,89(2000);U.L¨o ring,B.Ch.Metsch,H.R.Petry,Eur.Phys.J.A10, 447(2001).8.Q.B.Li and D.O.Riska,Nucl.Phys.A791,406(2007).9.P.Geiger and N.Isgur,Phys.Rev.D55,299(1997).10.P.Geiger and N.Isgur,Phys.Rev.Lett.67,1066(1991);Phys.Rev.D44,799(1991);ibid.47,5050(1993).Roelof Bijker,Elena Santopinto:Flavor asymmetry of the nucleon sea in an unquenched quark model311. E.Santopinto and R.Bijker,these proceedings.12. A.W.Thomas,Phys.Lett.B126,97(1983);E.M.Henley and ler,Phys.Lett.B251,453(1990).13.S.Capstick and W.Roberts,Phys.Rev.D49,4570(1994).14.R.Bijker and E.Santopinto,work in progress.。
Fuzzy Logic and Systems
Fuzzy Logic and SystemsFuzzy Logic and Systems: A Comprehensive OverviewIn the realm of computational intelligence, fuzzy logic and systems have emerged as a powerful tool for dealing with uncertainty and imprecision. This essay aims to provide a comprehensive overview of fuzzy logic and its applications in various systems, highlighting the significance of this approach in modern technology.Introduction to Fuzzy LogicFuzzy logic, introduced by Lotfi A. Zadeh in 1965, is a mathematical logicthat deals with approximate reasoning. Unlike traditional binary logic, which is based on crisp values of true and false, fuzzy logic allows for a range of truth values between 0 and 1. This flexibility enables fuzzy logic to model human reasoning more accurately, particularly in situations where data is incomplete or ambiguous.Fundamentals of Fuzzy LogicAt the core of fuzzy logic is the concept of a fuzzy set, which is a generalization of a classical set. A fuzzy set is characterized by a membership function that assigns each element a degree of membership between 0 and 1. This degree reflects the extent to which an element belongs to the set. Fuzzy logic also employs linguistic variables, which are used to express concepts in a natural language-like manner, making it easier for humans to interact with the system.Fuzzy Logic OperationsFuzzy logic operations include fuzzy union, intersection, and complement. These operations are analogous to classical set operations but are adapted to handle the fuzzy nature of the membership values. The union of two fuzzy sets, for example, combines the membership values of their elements, while the intersectionfinds the minimum membership value among the elements of both sets. The complement operation inverts the membership values, assigning a value of 1 minus the original membership to each element.Applications of Fuzzy LogicFuzzy logic has found applications in a wide range of fields, includingcontrol systems, decision-making, and artificial intelligence. In control systems, fuzzy logic controllers (FLCs) are used to manage complex processes byinterpreting input data and generating appropriate control actions. FLCs are particularly useful in situations where traditional control methods struggle with non-linear or time-varying systems.In decision-making, fuzzy logic helps to address the uncertainty inherent in human judgments. By incorporating fuzzy sets and linguistic variables, decision-makers can create more nuanced and context-sensitive decision models. This approach is particularly valuable in fields such as finance, where decisions must be made with incomplete or uncertain information.Artificial intelligence also benefits from fuzzy logic, as it allows systems to process and interpret ambiguous or imprecise data. This capability is crucialfor developing systems that can interact with humans in a more natural andintuitive manner.Challenges and LimitationsDespite its many advantages, fuzzy logic also faces challenges and limitations. One of the primary concerns is the difficulty in designing and tuning fuzzy systems, particularly when dealing with complex problems. The process of determining appropriate membership functions and rule sets can be time-consuming and requires a deep understanding of the problem domain.Another challenge is the interpretability of fuzzy systems. While fuzzy logic can handle uncertainty and imprecision, it can sometimes be difficult for users tounderstand the reasoning behind the system's decisions. This lack of transparency can be a barrier to the widespread adoption of fuzzy logic in certain applications.Future DirectionsAs technology continues to advance, the role of fuzzy logic in systems is likely to grow. With the increasing prevalence of big data and the need to make sense of complex, uncertain information, fuzzy logic offers a valuable approach to processing and analyzing this data. Additionally, as systems become more integrated into our daily lives, the ability to handle ambiguity and uncertainty will be crucial for creating more human-like interactions.In the future, we can expect to see more research and development in the area of fuzzy logic, with a focus on improving the design and tuning processes, as well as enhancing the interpretability of fuzzy systems. This will help to overcome some of the current challenges and limitations, paving the way for even broader applications of fuzzy logic in various fields.ConclusionFuzzy logic and systems have proven to be a valuable tool for managing uncertainty and imprecision in a wide range of applications. From control systems to decision-making and artificial intelligence, fuzzy logic offers a flexible and powerful approach to dealing with complex problems. While challenges and limitations exist, ongoing research and development are likely to address these issues and further expand the potential of fuzzy logic in the years to come.In conclusion, fuzzy logic and systems represent an important area of study within the field of computational intelligence. As we continue to explore the potential of this approach, we can expect to see its influence grow, shaping the way we interact with technology and making our systems more adaptable and responsive to the complexities of the real world.。
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 of the expected 10-23 seconds! This particle was named the lambda particle (Λ0) and theproperty 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 10-23 seconds 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 the process. That can only occur by the weak interaction , and that leads to a much longerlifetime. 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 classic example of the need for the property called "color " in describing particles. Since quarks are fermions with spin 1/2, they must obey the Pauli exclusion principle and cannot exist in identical states. So with three strange quarks, the property which distinguishes them must be capable of at 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 propertiesIndexParticle conceptsHyperPhysics ***** Quantum PhysicsR 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。
Quantum Mechanics
Quantum MechanicsQuantum Mechanics is a branch of physics that deals with the behavior of matter and energy at the smallest scales, such as atoms and subatomic particles. It is a complex and fascinating field of study that has revolutionized our understanding of the world around us. However, it is also a subject that can be difficult to grasp, with concepts that challenge our intuition and require us to think in new ways. In this essay, I will explore the basics of Quantum Mechanics, its implications for our understanding of reality, and some of the controversies surrounding it.One of the key principles of Quantum Mechanics is the idea of wave-particle duality. This means that particles, such as electrons, can exhibit both wave-like and particle-like behavior, depending on the context. For example, when an electron is observed, it appears as a particle, but when it is not observed, it behaves like a wave. This concept challenges our everyday understanding of the world, where objects are either particles or waves, but not both.Another important principle of Quantum Mechanics is uncertainty. Thisprinciple states that it is impossible to know both the position and momentum of a particle with absolute certainty. The more precisely we know one of these values, the less precisely we can know the other. This principle has profound implications for our understanding of causality and determinism, as it suggests that the behavior of particles is inherently unpredictable.Quantum Mechanics also introduces the concept of superposition, which is the idea that a particle can exist in multiple states at the same time. For example, an electron can exist in two different energy states simultaneously. This concept is difficult to grasp, as it challenges our everyday experience of the world, where objects are either in one state or another, but not both.One of the most famous experiments in Quantum Mechanics is the double-slit experiment. In this experiment, a beam of particles, such as electrons, is fired at a screen with two slits. When the particles pass through the slits, they create an interference pattern on a detector behind the screen, as if they had behaved like waves. This experiment demonstrates the wave-particle duality of particles and the concept of superposition.The implications of Quantum Mechanics for our understanding of reality are profound. It suggests that the world is fundamentally uncertain and that particles can exist in multiple states at the same time. This challenges our everyday experience of the world, where things are either one way or another, but not both. It also raises questions about the nature of causality and determinism, asparticles seem to behave in unpredictable ways.There are also controversies surrounding Quantum Mechanics. One of the most famous is the Einstein-Podolsky-Rosen (EPR) paradox. This paradox suggests that if two particles are entangled, meaning they have a correlated quantum state, then measuring one particle will instantaneously affect the state of the other particle, even if they are separated by large distances. This concept challenges our understanding of causality and suggests that information can travel faster thanthe speed of light, which is not allowed by relativity.Another controversy is the interpretation of Quantum Mechanics. There are several interpretations of Quantum Mechanics, each with its own strengths and weaknesses. The most popular interpretation is the Copenhagen interpretation,which suggests that the act of observation collapses the wave function of a particle, causing it to behave like a particle rather than a wave. However, this interpretation has been criticized for being too anthropocentric and for not providing a clear explanation of how the act of observation causes the collapse.In conclusion, Quantum Mechanics is a complex and fascinating field of study that challenges our understanding of the world around us. Its principles of wave-particle duality, uncertainty, and superposition have profound implications forour understanding of reality. However, there are also controversies surrounding Quantum Mechanics, such as the EPR paradox and the interpretation of the theory. Despite these challenges, Quantum Mechanics has revolutionized our understandingof the world and continues to be an active area of research and discovery.。
Spacings of Quarkonium Levels with the Same Principal Quantum Number
The principal quantum number N is that which labels nonrelativistic Coulomb energy levels through the Balmer formula EN ℓ ∝ −1/N 2 . It is related to the radial quantum number nr and the orbital angular momentum ℓ via N = nr + ℓ (nr = 1, 2, 3, . . .), where nr − 1 ≡ n corresponds to the number of nodes of the radial wave function between r = 0 and r = ∞. Our result amounts to a formula for levels EN ℓ linear in ℓ for a given N : EN ℓ = F (ν, N ) − G(ν, N )ℓ (1)
To be submitted to Phys. Rev. D. ´ URA 14-36 du CNRS associ´ ee ` a l’Ecole Normale Sup´ erieure de Lyon et ` a l’Universit´ e de Savoie
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1
ABSTRACT The spacings between bound-state levels of the Schr¨ odinger equation with the same principal quantum number N but orbital angular momenta ℓ differing by unity are found to be nearly equal for a wide range of power potentials V = λr ν , with EN ℓ ≈ F (ν, N ) − G(ν, N )ℓ. Semiclassical approximations are in accord with this behavior. The result is applied to estimates of masses for quarkonium levels which have not yet been observed, including the 2P cc ¯ states and the 1D b¯ b states. I. INTRODUCTION The properties of heavy quarkonium (cc ¯ and b¯ b) levels have provided useful insights into the nature of the strong interactions. At short distances these interactions appear to be characterized by a Coulombic potential associated with asymptotically free single-gluon exchange [1], while at large distances the interquark force is consistent with a constant, corresponding to a separation energy increasing linearly with distance [2]. An effective power potential V ∼ r ν , with ν close to zero, provides a useful interpolation between these two regimes for cc ¯ and b¯ b levels when the interquark separation ranges between about 0.1 and 1 fm [3]. Charmonium (cc ¯) levels have been identified up to the fourth or fifth S-wave, the first P-wave, and the first D-wave excitation. (We are ignoring fine structure and hyperfine structure for the moment.) Six S-wave levels and two P-wave levels have been found in the upsilon (b¯ b) family. Many additional levels are expected but have not yet been seen. There are some reasons of current interest for predicting their positions in a relatively model-independent manner. For example: (1) It has been suggested [4, 5] that, depending on its exact mass, the second charmonium P-wave level (which we shall denote as χ′c (2P )) could play a role in the hadronic production of the ψ ′ (2S ) state. (2) The first D-wave level of the b¯ b system, which we shall call Υ(1D ), may be accessible to experiments of improved sensitivity at the CLEO detector, both in direct production of the 3 D1 states via the e+ e− channel and through electromagnetic transitions from the Υ(3S ) state [6]. Explicit calculations in nonrelativistic quark models of the masses of the χ′c (2P ) and Υ(1D ) states have tended to have very small spreads [6, 7]. Any interquark potential which reproduces the known quarkonium levels is well-enough determined to leave little room for variation in predictions of these levels. However, in the course of examining these predictions within the context of power potentials V = λr ν , with λν > 0, we were struck by a curious feature: The spacings between levels with the same principal quantum number but orbital angular momenta differing by unity are nearly identical for a wide range of values of ν . 2
VortexCriticaltotheMostPowerfulTelescopetoMapthe
Vortex Critical to the Most Powerful Telescope to Map the UniversePrismTech’s Vortex Intelligent Data-sharing Platform is being used in a historical attempt to draw the first 3D map of the universe. Serving to control, monitor and regulate the data interfaces and ensuring the right data gets to the right place in real-time within the new Large Synoptic Survey Telescope (LSST) telescope facility, Vortex was chosen to process data on a colossal volume in an attempt to scale the universe generating over 30 terabytes of data 24/7.About AURALSST is a project organized by the Association of Universities for Research in Astronomy (AURA) and funded by the U.S. Department of Energy and the National Science Foundation with support through a public-private partnership featuring an immense collaboration of countries, companies and universities, including more than 400 scientists and engineers. The eight metre wide giant telescope will sit on top of the Chilean mountain of Cerro Pachón, It will work in tandem with the world’s largest digital camera, weighing in at more than 6,000 pounds and snapping 3.2-gigapixel images every 20 seconds as it surveys the stars and generates 30 terabytes of data night after night for 10 years. LSST has been identified as a national scientific priority in reports by diverse national panels, including several National Academy of Sciences and federal agency advisory committees Key Challenges for the LSSTThe data generated by the LSST will show scientists more of the universe than humanity has seen looking through all previous telescopes combined, providing 1,000 images of every part of the sky and acquiring all that scientific information involves an enormous amount telemetry data that must be captured . Mapping the universe is not a just a colossal job, it is mission-critical operation that involves a huge amount of time and money. The mountain of data that must be captured, monitored and analyzed in order to reactively adjust and control the telescope in a 24/7 operation is astonishing, making the selection of the data-sharing backbone of the LSST critical to the success of the project.“It’s not just that DDS makes it easier and faster for this telemetric data to be shared, analyzed and acted upon throughout the system. What Vortex provides the developers is the freedom to concentrate on the application… not on the communication.That is entirely taken care of for us with Vortex; it was specifically chosen over other DDS implementations because of its superior shared-memory architecture” German Schumacher , Software Manager, AURAIn the case of LSST, over 96-percent uptime over a 10-year period is required to ensure there are no risks to the $500 million program investment and no corruption of the experiment data during this timeframe. Vortex enables real-time monitoring and predictive capabilities, which will ensure the survey does not suffer disruptions in its cosmic explorations.Real Benefits of the LSSTThe data that Vortex is set to handle will come from the largest light-gathering source in the world. The LSST will zero in on some of the faintest objects in the sky and populate a database containing 20 billion objects. Beyond the pure science aspect of the project, scientists will also use LSST to track asteroids and determine whether they pose any impact threat to the earth.The depth and detail of the incoming information will facilitate creation of a 3D map of the cosmos. LSST will also give scientists a better understanding of the solar system beyond Neptune, including distant objects in the Kuiper Belt. The data is expected to reveal just how far material extends into the outer reaches of our solar system.For LSST, it is critical that the applications do not handle the data. Without Vortex, the developed applications would have to shoulder the tasks of message interpretation and state management.How Vortex HelpedVortex’s is based on the Data Distribution Service (DDS) standard developed by the Object Management Group (OMG). In addition to its real-time data sharing capabilities, Vortex provides a user friendly development environment that helps enable fast and efficient system development requiring the involvement of fewer people – without Vortex to help simplify overall system design, the team required to do develop the data-sharing functionality of the system would have been three times larger than was actually needed.A common characteristic of Vortex applications is mission-criticality, an attribute inextricably tied to a system’s intolerance for failure. Since the data-sharing infrastructure impacts all aspects of a system, its reliability, robustness and fault-tolerance become synonymous with operational success.Vortex has a proven track record of wide spectrum of applications, including smart energy, smart transportation, industrial automation, and healthcare environments. It is deployed in a variety of air-traffic control, manufacturing, financial automation, smart agriculture, grid management, smart city and financial trading systems.Vortex real-time monitoring and predictive capabilities will ensure the survey does not suffer disruptions in its cosmic explorations, securing the data, its quality and the entire equally-massive investment.The Future of LSSTThe collaborative work of many countries, universities and companies on LSST will seek to shed light on such phenomena as dark matter and dark energy, providing clues to the nature and origin of the universe.With the help of Vortex data-sharing capabilities, LSST will manage to transmit huge flow of data from the heavens and map the universe in 3D that will be made available to over 400 scientists and engineers all over the world in real-time for the entire 10-year project life span.For More InformationTo learn more about PrismTech and find out how its Vortex Intelligent Data Sharing Platform is being used on the LSST project, contact your PrismTech Sales representative or visit: /lsst。
1-2-3-flavor color superconductivity in compact stars
Phase transition to quark matter: nucleon dissociation - The task to describe the phase transition from nuclear matter to quark matter as a dissociation of three-quark bound states into their quark constituents (Mott transition) has not yet been solved. Only some aspects have been considered yet, e.g., within a nonrelativistic potential model [8] or within the NJL model [9]. We will consider a chemical equilibrium of the type n + n ↔ p + 3d, which results in a mixed phase of nucleons and down quarks once the d-quark chemical potential exceeds the critical value. This scenario is analogous to the dissociation of nuclear clusters in the crust of neutron stars (neutron dripline) and the effect may therefore be called the d-quark dripline. We approximate the quark and nucleon components as subphases described by separate models, e.g., by the DBHF approach and a three-flavor quark model of NJL type [10, 11, 12, 13]. The partition function for the latter is given in path-integral representation by
SYSTEMS AND METHODS FOR SUPERCONDUCTING FLUX QUBIT
专利名称：SYSTEMS AND METHODS FORSUPERCONDUCTING FLUX QUBIT READOUT 发明人：BERKLEY, Andrew, J.申请号：US2011/060216申请日：20111110公开号：WO2012/064974A3公开日：20120705专利内容由知识产权出版社提供专利附图：摘要：Systems and methods for reading out the states of superconducting flux qubits may couple magnetic flux representative of a qubit state to a DC-SQUID in a variable transformer circuit. The DC-SQUID is electrically coupled in parallel with a primaryinductor such that a time-varying (e.g., AC) drive current is divided between the DC-SQUID and the primary inductor in a ratio that is dependent on the qubit state. The primary inductor is inductively coupled to a secondary inductor to provide a time-varying (e.g., AC) output signal indicative of the qubit state without causing the DC-SQUID to switch into a voltage state. Coupling between the superconducting flux qubit and the DC-SQUID may be mediated by a routing system including a plurality of latching qubits. Multiple superconducting flux qubits may be coupled to the same routing system so that a single variable transformer circuit may be used to measure the states of multiple qubits.申请人：D-WAVE SYSTEMS INC.,BERKLEY, Andrew, J.地址：100 - 4401 Still Creek Drive Burnaby, British Columbia V5C 6G9 CA,100 - 4401 Still Creek Drive Burnaby, British Columbia V5C 6G9 CA国籍：CA,CA代理人：ABRAMONTE, Frank et al.更多信息请下载全文后查看。
Tube connection in particular for connecting two t
专利名称：Tube connection in particular for connecting two tubular fuselage parts of a flying body 发明人：BROSS, DIRK,FISCH, PETER GERD申请号：EP97106217申请日：19970416公开号：EP0803675A3公开日：19980930专利内容由知识产权出版社提供摘要：The missile has a body made up of two (10,12) or more interlocking end-joined sections of circular cross-section. When assembled, there is no difference in the outer diameter of the assembly in the interface zone. A tubular flange interface between the two sections is sub-divided into two arcs (14,18,16,20) as seen in cross-section. The inner face of the body within the first arc is of reduced thickness, and receives the matching face of the second section. The interlocking outer diameter of the second section is reduced at the interface to provide for a non-distortion push-fit. The interface within the second arc of the assembled body is a reversal of that in the first arc. The assembled and interlocked interface flanges are then held in place by bolts inserted through radial holes (22,24) in the flanges.申请人：BODENSEEWERK GERAETETECHNIK GMBH更多信息请下载全文后查看。
双极型有机场效应晶体管英文
双极型有机场效应晶体管英文The dual-gate organic field-effect transistor (OFET) is a fascinating device that combines two gates to control the flow of current, offering a more nuanced approach to electronic control.This technology is particularly appealing in the realm of flexible electronics, where the ability to manipulate electronic properties with precision is paramount. The dual-gate design allows for a fine-tuned response to external stimuli, making it a promising candidate for applications in sensors and displays.In terms of operation, the dual-gate OFET modulates the charge carriers within the organic semiconductor layer, which can be either p-type or n-type, depending on the material used. This modulation is what enables the transistor to switch between on and off states, much like a traditional silicon transistor.One of the key advantages of this technology is its potential for low power consumption. By using organic materials, which are inherently less power-hungry than their inorganic counterparts, the dual-gate OFET could lead to more energy-efficient electronic devices.Looking ahead, the integration of dual-gate OFETs into wearable technology and smart fabrics could revolutionize theway we interact with our environment. Imagine clothing that can change color or pattern in response to your mood or the weather – a concept that is now closer to reality thanks to advancements in this field.As researchers continue to refine the performance and stability of dual-gate OFETs, we can expect to see a surge in innovative applications that leverage the unique properties of these devices, further blurring the line between electronics and everyday objects.。
FLUX-DIFFERENCE SPLITTING
A flux-difference splitting scheme with a modified multidimensional dissipation for high-speed compressible flow analysis on unstructured meshes is presented. The scheme eliminates unphysical flow behaviors such as a spurious bump of the carbuncle phenomenon that occurs on the bow shock from flow over a blunt body, and the expansion shock generated from flow over a forward facing step. The switching function suggested by Quirk is implemented as a choice to detect the vicinity of strong shock. The proposed scheme is further extended to obtain higher-order spatial and temporal solution accuracy. The scheme is, in addition, combined with an adaptive meshing technique that generates unstructured triangular meshes to resemble the flow phenomena for reducing computational effort. The entire procedure is evaluated by solving several benchmarks as well as steady-state and transient high-speed compressible flow problems. Key Words: shock instabilities, carbuncle phenomenon, Roe’s FDS, entropy fix, H -correction. I. INTRODUCTION High-speed compressible flows normally involve complex flow phenomena, such as strong shock waves, shock-shock interactions and shear layers. Various numerical inviscid flux formulations have been proposed to solve an approximate Riemann problem. Among these formulations, the flux-difference splitting scheme by Roe (1981) is widely used due to its accuracy, quality and mathematical clarity. However, the scheme may sometimes lead to unphysical flow solutions in certain problems, such as the carbuncle phenomenon (Perry and Imlay, 1988) with a spurious bump in the bow shock from flow over a blunt body. The scheme may not provide an accurate solution for the complex impinging shock phenomenon yielding kinked mach stem (Quirk, 1994) generated from a moving shock over a ramp. In the oddeven decoupling problem, an unrealistic perturbation
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a rXiv:h e p-la t/21236v12Dec221ITEP-LAT/2002-30KANAZAWA 02-38Flux Tubes of Two-and Three-Quark System in Full QCD ∗H.Ichie a ,V.Bornyakov a ,T.Streuer b and G.Schierholz b a Institute for Theoretical Physics,Kanazawa University,Kanazawa 920-1192,Japan b NIC/DESY Zeuthen,Platanenallee 6,D-15738Zeuthen,Germany We study the abelian color flux of two-and three-quark systems in the maximally abelian gauge in lattice QCD with dynamical fermions.We find that the abelian flux tube formed between quark and antiquark is very much the same as in quenched QCD up to quark separations of R ∼2fm.The profile of the color electric field in three-quark system suggests Y ansatz,which might be interpreted as the result of the vacuum pressure in the confined phase.In order to clarify the flux structure,we investigate the color electric field of the three-quark system splittting the abelian gauge field into the monopole and photon parts.1.Introduction In the dual superconductor picture of confinement,the color flux tube is formed due to the dual Meissner effect caused by monopole condensation [1].Such a picture is based on the abelian gauge theory obeying Maxwell’s equations,and ’t Hooft built a bridge between the abelian gauge theory and QCD introducing abelian gauge fixing and abelianprojection [1].In the last decade,lattice simulations,especially in the maximally abelian (MA)gauge,presented evidence in favor of this scenario.The most previous lattice studies,however,have been performed in SU(2)gauge theory without dynamical quarks.We consider the more realistic case of lattice QCD with dynamical quarks.Weextend the study of the abelian color flux tube between staticquark and antiquark (Q ¯Q)to SU(3)gauge group and make first investigation of the abeliancolor flux tube in the three-quark (3Q)system.In QCD the string formed between static quark and anti-quark breaks and two static-light mesons are created,when the separation is large enough.We measure abelian flux tube with large quark separation and look for effects of the string breaking.2.Operators and simulation detailsThe observables describing local structure of the flux tube are determined from the correlation function between an appropriate operator O (s )and abelian Wilson loop [2Red quarkBlue quark Green quarkquark antiquarkAbelian Wilson Loop 3 Quark Abelian Wilson LoopFigure1.Abelian Wilson loop for2-quark system(left)and3-quark system(right).2,3]:ˆO(s)= O(s)W abel3Trs∈Cuµ(s)=13!|ǫabc|u a R·u b G·u c B,with u a C=s∈ΓCu aµ(s),ΓC=ΓR,ΓG,ΓBwith a path product of abelian link variables along the stapler-type pathΓC shown in Fig.1.Unlike in the nonabelian Wilson loop case,the color of quarks does not change during the propagation,because the off-diagonal components of the gaugefield are frozen in the abelian projected theory.Most measurements are done in the plane which is a central time slice of the abelian Wilson loop shown also in Fig.1.The simulations were performed using lattice configurations generated with N f=2non-perturbatively O(a)improved Wilson fermions with at mπ/mρ∼0.7[4].The link variables arefixed to maximally abelian gauge with a simulated annealing algorithm.For noise reduction,we used a smearing method for spatial links of the abelian Wilson loop.3.Abelian Flux TubeFig.2shows the structure of Q¯Q abelianflux tube in full lattice QCD for R∼0.5fm. Similar to SU(2)[2]and SU(3)[5]gluodynamics,we observe enhancement in the action density.Opposite to this,the monopole density is suppressed in agreement with vanishing of the dual Higgsfield in the center region of theflux tube.Furthermore,in the plane perpendicular to theflux tube,the solenoidal monopole current is clearly seen.All these observations are in accordance with the dual superconductor picture of confinement in particular with the assumption that the color electricfield is squeezed intoflux tubes by the super monopole current.We expect theflux tube to disappear eventually if the static charges are pulled apart beyond a certain distance.This distance is expected to be around1.2fm[6].We have studied the distribution of the color electricfield for Q¯Q separation up to≈2fm.We3162024283236812162025507516202428323681216201.522.5457. C.Alexandrou,Ph.de Forcrand,and A.Tsapalis,Phys.Rev.D65(2002)054503.8.T.T.Takahashi,H.Suganuma,Y.Nemoto et al.Phys.Rev.D65(2002)114509.9.Y.Koma,E.-M.Ilgenfritz,T.Suzuki,H.Toki,Phys.Rev.D64(2001)014015.10.M.N.Chernodub and D.A.Komarov,JETP Lett.68(1998)117.。