THE VACUUM OF LATTICE GAUGE THEORY WITH FERMIONS AND SPONTANEOUS CHIRAL SYMMETRY BREAKING*

The vacuum structure of lattice gauge theory with femicns is studied by the variational method.The fermion condensate <ψψ> is given as a function of l/g².     

Quark chiral condensate from the overlap quark propagator

From the overlap lattice quark propagator calculated in the Landau gauge,we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data.The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N_f = 2 + 1flavors.Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) Ge V.We obtain ψψ (2 GeV)MS =(-304(15)(20) MeV)~3in the SU(2) chiral limit.     

Search for ψ(4S) → ηJ/ψ in B~±→ ηJ/ψK~± and e~+e~-→ ηJ/ψ processes

We search for the ψ(4S) state in the B~±→ηJ/ψK~± and e~+e~-→ηJ/ψ processes based on the Belle measurements with the assumed mass M =(4230±8) MeV/c~2 and width Γ =(38±12) MeV. No significant signal is observed in the ηJ/ψ mass spectra. The 90% confidence level upper limit on the product branching fraction B(B~±→ψ(4S)K~±)B(ψ(4S)→ηJ/ψ) 6.8×10~(-6) is obtained in the B~±→ηJ/ψK~± decays. By assuming the partial width of ψ(4S)→e~+e~-to be 0.63 ke V, a branching fraction limitB(ψ(4S)→ηJ/ψ) 1.3% is obtained at the 90%confidence level in e~+e~-→ηJ/ψ, which is consistent with the theoretical prediction.     

Resolved Photoproduction of J/ψ at HERA

The J/ψ photoproduction via resolved photon process at HERA is studied. It turns out that the J/ψ production is dominated by the leading order production process in low pt range (p_t < 4 GeV), while in the high pt range (p_t > 4 GeV), it is dominated by the fragmentation processes. The difference of J/ψ cross section caused by using GRV and DO photon structure functions is large, especially in the large negative rapidity range. Hence it is possible to use the J/ψ photoproduction process to probe the parton distribution of photon and proton, as well as to test the gluon and heavy quark fragmentation of J/ψ from the perturbative QCD.     

DIAGONALIZATION OF ANOMALOUS DIMENSION MATRICES OF HIGHER TWIST OPERATORS AND CONFORPIAL COVARIANCE

Anomalous dimension matrices of operators based on the twist-3 operator ψγ₅ψ (or ψψ)are calculated and diagonalized. We find that for these operators the diagonal operators are not conformal operators. The higher twist effects of the pionic asymptotic B-S wave function and form factor are also investi- gated.     

QCD Sum Rules and J/ψ Suppression in Hot Hadronic Matter and Quark-Gluon Plasma

A consistent treatment based on the QCD sum rules at finite temperature has been established to calculate the J/ψ suppression in hot hadronic matter (HM) and quarkgluon plasma (QGP) respectively. We have found that the J/ψ suppression occurs in both hadronic matter and quark-gluon plasma, but a J/ψ mass shift of about 0.49 GeV exists in QGP background only. The results obtained by QCD sum rules and by potential model are compared.     

GCP Code and Analysis of J/ψ Suppression in p-A and A-A Collisions

Using the General Cascade Program (GCP), the production and absorption of J/ψ,in p-A and A-A collisions have been studied. Nucleon absorption mechanism and comoverabsorption mechanism are considered to investigate the J/ψ suppression. The results agreewell with experimental data of J/ψ production, escept for the data in Pb-Pb collision.     

Study of the rare decay J/ψ→e~+e~-φ

We study the decay process of J/ψ→e~+e~-φ where the relatively clean electromagnetic(EM) transitions appear at leading order at tree level while the hadronic contributions only emerge via hadronic loop transitions. We include the low-lying scalar f_0(980) and pseudoscalar η/η as the dominant contributions in the evaluation of the hadronic loop contributions. It is found that the hadronic effects are negligible compared with the EM contributions.The decay width of J/ψ→e~+e~-φ is determined to be about 2.12 × 10~(-6) ke V if there is no other leading mechanism contributing. This result will be tested by the BESIII experiment with a large J/ψ data sample.     

The Relation Between the Two Methods for Describing Markovian Noises

A general method used to calculate the time-dependent probability distribution from the switching time distribution ψ(t, a) and the transition probability ρ(a, b) for Markovian noises is presented, and the way how to describe the noises treated as diffusion processes such as O-U noise by the jump model (namely, ψ(t, a) and ρ(a, b)) is given, which makes it possible to apply the stochastic trajectory technique and the definition method to the above noises.     

强电场对夸克胶子等离子体中粲夸克偶素演化的影响(英文)

在极端相对论重离子碰撞中,高速运动的重离子会产生很强的电场。在碰撞的早期电场强度大小在eE~m_π2的量级。在夸克胶子等离子体中,强电场将会对粲夸克偶素的演化产生巨大的影响。我们用含时薛定谔方程计算夸克胶子等离子体中由高速运动电荷所产生强电场对重夸克偶素演化的影响。此电场可以导致不同角动量态之间的跃迁。为了研究此效应,比较了有电场和无电场情况下J/ψ、ψ'以及χ_c的产额。计算结果表明,在碰撞早期电场会导致J/ψ解离;同时,χ_c也由电场导致的J/ψ的跃迁而产生。     

Associated J/ψ+γ Production Through Double Pomeron Exchange: the Nature of the Pomeron and Hard Diffractive Factorization Breaking

We present a study of associated J/ψ+γ production through double pomeron exchange at energies reached at the Fermilab Tevatron.and CERN LHC based on the Ingelman-Schlein model for hard difiactive scattering and the factorization formalism of nonrelativistic QCD for quarkonia production. We find that the process p+p→p +p + J/ψ+γ + X can be used to probe the gluon content of the pomeron and study the nature of hard difiactive factorization breaking.     

ξ(2230) Is Likely to Be a Glueball

On the basis of the recent results of ξ(2230) → π⁺π^-, pp and ξ(2230) → K⁺K^-, K_sK_s, measured by the BES Collaboration in J/ψ radiative decays, combined with the PSI85 experiment of pp → ξ(2230) → KK we argue that because of its very narrow partial decay widths to nn and KK (less than 1 MeV), its large production rate in J/ψ radiative decays (BR(J/ψ → γξ> 2.3×10^-3), and its flavor-symmetric couplings to ππ and KK, the ξ(2230) is very likely to to be a J^PC= (even)⁺⁺ glueball.     

Analysis of Collective Flow in High Energy Heavy-Ion Collisions in the Relativistic VUU Approach

We have calculated the collective flow for Ar+KCl collisions of 1200 MeV/A by using the relativistic Vlasov-Uehling- Uhlenbeck (VUU) equation based on the QHD-I model of Walecka. The tensitivity of flow characterized by C(ψ)a nd (P_x(Y))to mean field and in-medium NN scattering cross section is studied. It is found that the azimuthal correlation function C(ψ) is reduced dramatically after inserting the collision term and then varies very slowly between NN cross sections from σ = 10 mb to 55 mb and reaches the minimum at σ = 35 mb, while the in-plane mean transverse momentum (P_x(Y))in creases slowly all the way from σ = 0 mb to 55 mb. The collective flow is very sensitive to the momentum dependence (indicated by the effective mass m⁰) of the mean field and less sensitive to the compression modulus K and the cross sections from σ = 10 mb to 55 mb. The numerical results were compared with the experimental data, and we found that the agreement for both (P_x(Y)) and C(ψ) can be reached with the same set of mean field parameters as well as the appropriate NN cross section in collision terms.     

Strange quarkonium states at BESⅢ

We present physics opportunities and topics with the s states(strangeonia)that can be studied with the BES detector operating at the BEPC collider.Though the φ and η/ states have long been established experimentally,only a handful of strangeonia are well known,in contrast to the rich ccharmoium system.An overview of the s states and their experimental status is presented in this paper.The BES experiment has collected the world’s largest samples of J/ψ,ψ(2S),ψ(3770),and direct e+e-annihilations at energies below the J/ψand above 3.8 Ge V,and will continue to accumulate high quality,large integrated luminosity in theτ-charm energy region.These data,combined with the excellent performance of the BESⅢ detector,will offer unprecedented opportunities to explore the s system.In this paper we describe the experimental techniques to explore strangeonia with the BESⅢ detector.     

Exact calculation of the Fermion determinant in chiral QCD2 reflecting the full regularization dependence

The fermion determinant of non-abelian anomalous gauge theory in two space-time dimensions is computed using the path-integral approach. The regularization dependence of the fermion determinant is worked out. Apart from a regularization dependentA ² term, the fermion determinant contains a Wess-Zumino-Witten anomaly functional.     

RADIATIVE DECAY J/ψ→γη′ IN PERTURBATIVE QCD

The deccy rate of J/ψ→γη^′ is calculated by using the light-cone wave function of the flavor singlet pseudoscalar. The result is reasonably in agreement with the experiment.     

Perfect Single Qubit Mirroring Effects on Two and Three Maximally Entangled Qubits

Perfect quantum state mirroring in a chain of N spins is defined as the condition in which the state |iof the chain is swapped into the state |N-i within a time evolution interval τ.Such a phenomenon is an interesting way of transfering entanglement.An expressions for the perfect mirroring of a single qubit contained in a spin chain were proposed in the past.We exploit such an expressions for calculating the evolution times in chains of both two and three spins.In the case of a chain of two qubits,we derive conditions under which the associated four Bell states diagonalize the Hamiltonian.It is found that for the two Bell states |Φ+and|Φ-,perfect mirroring does not occur(i.e.entanglement is not preserved under swapping).On the other hand,perfect single qubit mirror effect(entanglement preservation) indeed occurs for the other two Bell states |Ψ+and|Ψ- which are mapped into |Φ+and|Φ-respectively.For the case of a chain of three qubits,the effects of a perfect single qubit mirroring on a set of four maximally entangled three qubit states ψ1,ψ2,χ1,and χ2 are studied.Due to the fact that quantum mirroring preserves maximal entanglement,the states ψ1 and ψ2 are not altered.However,quantum mirroring changes the states χ1 and χ2 only if we apply perfect quantum state mirroring in the site a=1 of the three qubits spin chain.The above constrains the preservation of maximal entanglement under qubit mirroring of such a state.Due to the fact that swapping has already been experimentally tested,a posible experimental implementations of single qubit mirroring is possible.     

Classical Behavior of the Dirac Bispinor

It is usually supposed that the Dirac and radiation equations predict that the phase of a fermion will rotate through half the angle through which the fermion is rotated, which means, via the measured dynamical and geometrical phase factors, that the fermion must have a half-integral spin. We demonstrate that this is not the case and that the identical relativistic quantum mechanics can also be derived with the phase of the fermion rotating through the same angle as does the fermion itself. Under spatial rotation and Lorentz transformation the bispinor transforms as a four-vector like the potential and Dirac current. Previous attempts to provide this form of transformational behavior have foundered because a satisfactory current could not be derived.⁽¹⁴⁾     

第Ⅰ类多模叠加态|ψ1(3)〉q中广义磁场的高次和压缩

构造了由多模相干态|{Z_j} > _q、多模真空态|{O_j} >_q和多模相干态的相反态|{-Z_j} > _q三者的线性叠加所组成的第Ⅰ类三态叠加多模叠加态光场|ψ₁⁽³⁾ > _q,利用多模压缩态理论,研究了态|ψ₁⁽³⁾ > _q中广义磁场分量的等幂次高次和压缩效应.结果发现:态|ψ₁⁽³⁾ > _q是一种典型的三态叠加多模非经典光场;当各模的初始相位和 满足一定的取值条件、并且态|ψ₁⁽³⁾〉_q中任意两态的态间初始相位差(θ_pq^(R)-θ_0q⁽⁰⁾)、(θ_nq^(R)-θ_0q⁽⁰⁾)和(θ_pq^(R)-θ_nq^(R))等分别在各自的闭区间内连续变化时,则态|ψ₁⁽³⁾ > _q的广义磁场分量(即第一正交相位分量)总可分别呈现出周期性变化的、等幂次的奇数模-偶数次、偶数模-奇数次、偶数模-偶数次或者奇数模-奇数次的高次和压缩效应.     

About the chiral symmetry breaking in QED<Subscript>3</Subscript>

The problem of the chiral symmetry breaking in QED₃ is considered by solving the Schwinger–Dyson equation for the fermion propagator in the ladder approximation using the Landau gauge for the photon propagator. Within the framework of the indicated approximation, different simplifications that allow expressions for the fermion mass function to be retrieved in an explicit form are analyzed. The results obtained are compared with the data of numerical analysis. It appears that the neglect of higher Gegenbauer harmonics in the kernel of the initial integral equation for the fermion mass function influences the dynamic mass value and the asymptotics of the mass function only weakly. On the other hand, it is established that the conclusion about a complicated structure of the fermion vacuum of the massive phase is an artifact of linearization of the Schwinger–Dyson equation kernel: consideration of the kernel nonlinearity yields a simple massive phase structure of the fermion vacuum.