The deconfinement transition in SU(2) lattice gauge theories

Using Monte Carlo techniques we study the SU(2) Yang-Mills system at finite temperatures for two different forms of lattice action, proposed by Villain and Monton respectively. In both cases the energy density ε exhibits a similar behaviour to the case of the Wilson action, being an order of magnitude smaller at lower temperatures and approaching the Stefan-Boltzmann limit for a free gluon gas at higher temperatures. The transition between these two temperature regimes appears rather abrupt and the specific heat of gluon matter exhibits a sharp peak at the transition point. The transition temperature, expressed in MeV, is found to be consistent in both the cases with that obtained by using the Wilson action, although in the natural units of the corresponding Λ-parameters it differs substantially, being 10.7, 27.3 and 42.8 for Manton, Villain and Wilson actions, respectively.     

The deconfinement transition in SU(2) gauge theory: A finite-size analysis

The finite-temperature deconfinement transition in pure SU(2) gauge theory is studied using finite-size analysis. The theory is formulated on a symmetric lattice with asymmetric couplings so the physical size of the spatial box can be changed continuously at a given physical temperature. Finite-size analysis based on the three-dimensional Ising model then permits the infinite-volume limit to be taken. The resulting critical temperature T_c scales according to asymptotic freedom and T_c/Λ_L = 44.0 ± 2.0.     

SU(2) gluodynamics above the deconfinement temperature

A physical model for describing SU(2) gluodynamics above the deconfinement temperature is developed on the basis of the operator-product-expansion method. The properties of the nonperturbative vacuum are parametrized in terms of gauge-invariant gluomagnetic correlation functions. The free energy of the system is calculated for T>T _c. The results obtained within the proposed model for the thermal properties of gluons (energy density, nonideality) are shown to agree with data coming from lattice calculations.     

Colour deconfinement and bag fusion in SU(2) Yang-Mills matter

We show that the SU(2) Yang-Mills system, above the critical temperature for colour deconfinement, approaches asymptotically free behaviour (Stefan-Boltzmann limit) in accord with the bag model.     

Chiral transition and deconfinement transition in QCD with the highly improved staggered quark (HISQ) action

We report preliminary results on the chiral and deconfinement aspects of the QCD transition at finite temperature using the Highly Improved Staggered Quark (HISQ) action on lattices with temporal extent of N _τ = 6 and 8. The chiral aspects of the transition are studied in terms of quark condensates and the disconnected chiral susceptibility. We study the deconfinement transition in terms of the strange quark number susceptibility and the renormalized Polyakov loop. We find reasonably good agreement between our results and the recent continuum extrapolated results obtained with the stout staggered quark action.     

Variational Cumulant Expansion on SU(2)⊗ SU(2) Chiral Model

The phase transition of the two-dimensional SU(2)⊗ SU(2) lattice chiral model has been studied by a variational cumulant expansion method. The internal energy and the specific heat are calculated to the 4th order correction and they are in good agreement with the Monte Carlo (MC) resdits. Except the behavior of the crossover region, similarities between this model and the four-dimensional SU(2) lattice gauge model are also discussed.     

An Extended Chiral SU(3) Quark Model

The chiral SU(3) quark model is extended by including the vector meson exchanges to describe the short range interactions. The phase shifts of NN scattering are studied in this model. Compared with the results of the chiral SU(3) quark model in which only the pseudo-scalar and scalar chiralfields are considered, the phase shifts of 1 So wave are obviously improved.     

Interacting boson model of collective nuclear states III. The transition from SU(5) to SU(3)

We study the transition from the vibrational, SU(5), to the rotational, SU(3), limit of the interacting boson model. We show how this model can be used to calculate energies, electromagnetic transitions, multipole moments, nuclear radii, and two-nucleon transfer intensities in transitional nuclei.     

Qq^- Q ^- q＇ States in Chiral SU（3） Quark Model

We study the masses of Qq^- Q ^- q＇ states with J^PC=0^＋＋,1＋＋ and 2^＋＋ in the chiral SU（3）quark model, where Q is the heavy quark （c or b） and q （q＇） is the light quark （u, d or s）. According to our numerical results, it is improbable to make the interpretation of [cn^-C^-n]1＋＋ and [cn^-C^-n]2＋＋ （n = u, d） states as X（3872） and Y（3940）, respectively. However, it is interesting to find the tetraquarks in the bq^-b^-q＇ system.     

Improved Threshold Constraints on Coupled-Channels Chiral SU(3) Dynamics from Kaonic Hydrogen

${\bar{K}}$ -nucleon interactions near threshold are investigated in the framework of coupled-channels dynamics based on the next-to-leading order chiral SU(3) meson-baryon effective Lagrangian. Accurate constraints are now provided by new high-precision kaonic hydrogen measurements. This constraint permits an updated analysis of the complex ${\bar{K}N}$ and πΣ coupled-channels amplitudes.     

Meson wave functions and SU(3) symmetry breaking

The wave functions of the pseudoscalar and vector mesons (K, ?, K¹, ?) are found using the QCD sum rules and are used for the calculation of the heavy quarkonium two-particle decay widths.     

KN Phase Shifts in Chiral SU（3） Quark Model

The isospin I = 0 and I = 1 kaon-nucleon S and P partial waves phase shifts have been studied in the chiral SU(3) quark model by solving a resonating group method equation. When the parameters of the chiral fields are taken in a reasonable region, the numerical results of S-wave are in good agreement with the experimental data, and the P-wave phase shifts can also be explained qualitatively by the calculation of only central force considered.     

Chiral Suppression and SU（3） Symmetry in Scalar Glueball Decays

We theoretically evaluate the decay rates of a scalar glueball up to the order O（αs）, where only two Feynman diagrams contribute and a special attention is paid on possible flavour SU（3） symmetry breaking in the process. It is concluded that the SU（3） flavour symmetry may be respected in any case. However, due to chiral suppression in Go →qq, F（Go →qq qq） very likely is larger than F（Go→qq）. These results are supported by the experimental data on the decays of xco（1P） （0^＋＋）. Based on this result, we propose a criterion to identify the scalar glueball.     

KN Phase Shifts in Chiral SU(3) Quark Model

The isospin I = 0 and I = 1 kaon-nucleon S and P partial waves phase shifts have been studied in the chiral SU(3) quark model by solving a resonating group method equation. When the parameters of the chiral fields are taken in a reasonable region, the numerical results of S-wave are in good agreement with the experimental data, and the P-wave phase shifts can also be explained qualitatively by the calculation of only central force considered.     

SU(3) ⊗ SU(2) ⊗ U(1) from D = 11 supergravity

In this paper we show that D = 11 supergravity admits an infinite discrete class of solutions having the phenomenological group SU(3) ? SU(2) ? U(1) as a symmetry of the internal space M₇. These solutions lead, in dimensional reduction, to SU(3) ? SU(2) ? U(1) gauge fields.In general all these spaces produce a complete breaking of supersymmetry except in one case where N = 2 supersymmetry survives. The parameter which classifies the solutions is a rational number q/p which describes the embedding of the stability subgroup SU(2) ? U(1) ? U(1) of M₇ in SU(3) ? SU(2) ? U(1). For all q/p ≠ 1 the holonomy group is SO(7) and all supersymmetries are broken. For q/p = 1 the holonomy group is SU(3) and two supersymmetries survive. In this last case we can also find a solution with internal photon curl $\text{F}{}_{\mathrm{\alpha \beta \gamma \delta }}\text{≠ 0}$. It breaks all sypersymmetries.