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On the Deconfinement Phase Transition in Hot Gauge Theories with Dynamical Matter Fields

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 Added by Oleg Borisenko
 Publication date 1998
  fields
and research's language is English




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The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. Since this ensemble implies a projection to the zero triality sector of the theory we introduce a proper quantity which is able to reveal a critical behaviour of the theory with fundamental quarks. We discuss the properties of both the chromoelectric and chromomagnetic sectors of the theory and show while electric charges carrying a unit of Z(N) charge are screened at high temperatures by dynamical matter loops, this is not the case for the Z(N) magnetic flux. An order parameter is constructed to probe the realization of local discrete Z(N) symmetry in the magnetic sector. We argue it can be used to detect a deconfinement phase being defined in terms of the screening mechanism as a phase of unscreened Z(N) flux. It may be detectable at long range via the Aharonov-Bohm effect. We discuss the possible phase structure of QCD in this approach.



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The phase structure of hot gauge theories with dynamical matter fields is reexamined in the canonical ensemble with respect to triality. We discuss properties of chromoelectric and chromomagnetic sectors of the theory and show whereas electric charges carrying a unit of Z(N) charge are screened at high temperatures via dynamical matter loops, this is not the case for the Z(N) magnetic flux. An order parameter is constructed to probe the realization of local Z(N) symmetry in the magnetic sector. We argue this order parameter may be used to detect the deconfinement phase transition which is defined in terms of the screening mechanism.
We provide the evidence for the existence of partially deconfined phase in large-$N$ gauge theory. In this phase, the SU($M$) subgroup of SU($N$) gauge group deconfines, where $frac{M}{N}$ changes continuously from zero (confined phase) to one (deconfined phase). The partially deconfined phase may exist in real QCD with $N=3$.
In the framework of a holographic QCD approach we study an influence of matters on the deconfinement temperature, $T_c$. We first consider quark flavor number ($N_f$) dependence of $T_c$. We observe that $T_c$ decreases with $N_f$, which is consistent with a lattice QCD result. We also delve into how the quark number density $rho_q$ affects the value of $T_c$. We find that $T_c$ drops with increasing $rho_q$. In both cases, we confirm that the contributions from quarks are suppressed by $1/N_c$, as it should be, compared to the ones from a gravitational action (pure Yang-Mills).
336 - M. Asakawa , T. Hatsuda 2003
Analyzing correlation functions of charmonia at finite temperature ($T$) on $32^3times(32-96)$ anisotropic lattices by the maximum entropy method (MEM), we find that $J/psi$ and $eta_c$ survive as distinct resonances in the plasma even up to $T simeq 1.6 T_c$ and that they eventually dissociate between $1.6 T_c$ and $1.9 T_c$ ($T_c$ is the critical temperature of deconfinement). This suggests that the deconfined plasma is non-perturbative enough to hold heavy-quark bound states. The importance of having sufficient number of temporal data points in the MEM analysis is also emphasized.
We study the deconfinement transition in two-flavour lattice QCD with dynamical overlap fermions. Our simulations have been carried out on a $16^3 times 6$ lattice at a pion mass around 500 MeV with a special HMC algorithm without any approximation such as fixed topology. We consider several temperatures from 220 MeV which is close to the deconfinement to 280 MeV which is above it. The dependence of the Polyakov loop, the chiral condensate, the Dirac spectra and the connected part of chiral susceptibility on the inverse gauge coupling has been studied. Our data indicates that the transition point lies between $beta = 7.6$ and $beta = 8.1$, but a more precise determination is not possible with our present statistics.
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