64 research outputs found
Low temperature relations in QCD
In this talk I discuss the low temperature relations for the trace of the
energy-momentum tensor in QCD with two and three quarks. It is shown that the
temperature derivatives of the anomalous and normal (quark massive term)
contributions to the trace of the energy-momentum tensor in QCD are equal to
each other in the low temperature region. Leading corrections connected with
-interactions and thermal excitations of and mesons are
calculated.Comment: 10 pages, LaTeX2e. Talk given at 12th International Seminar on
High-Energy Physics (QUARKS 2002), Novgorod, Russia, 1-7 Jun 200
Hadron resonance gas and nonperturbative QCD vacuum at finite temperature
We study the nonperturbative QCD vacuum with two light quarks at finite
temperature in the framework of hadron resonance gas. Temperature dependence of
the quark and gluon condensates in the confined phase are obtained. We
demonstrate that the quark condensate and one half (chromo-electric component)
of gluon condensate evaporate at the same temperature, which corresponds to the
temperature of quark-hadron phase transition. Critical temperature is T_c~190
MeV when temperature shift of hadron masses is taken into account.Comment: 8 pages, 4 figures; to appear in JETP Lett.; v2: references adde
Low temperature relation for the trace of the energy-momentum tensor in QCD with light quarks
It is shown that the temperature derivatives of the anomalous and normal
(quark massive term) contributions to the trace of the energy-momentum tensor
in QCD are equal to each other in the low temperature region. The physical
consequences of this relation are discussed.Comment: RevTeX, 4 pages, no figure
Instanton IR stabilization in the nonperturbative confining vacuum
The influence of nonperturbative fields on instantons in quantum
chromodynamics is studied. Nonperturbative vacuum is described in terms of
nonlocal gauge invariant vacuum averages of gluon field strength. Effective
action for instanton is derived in bilocal approximation and it is demonstrated
that stochastic background gluon fields are responsible for infra-red (IR)
stabilization of instantons. Dependence of characteristic instanton size on
gluon condensate and correlation length in nonperturbative vacuum is found. It
is shown that instanton size in QCD is of order of 0.25 fm. Comparison of
obtained instanton size distribution with lattice data is made.Comment: 10 pages, 4 figures; v2: minor corrections, to appear in JHE
Instanton infra-red stabilization in the nonperturbative QCD vacuum
The influence of nonperturbative fields on instantons in quantum
chromodynamics is studied. Nonperturbative vacuum is described in terms of
nonlocal gauge invariant vacuum averages of gluon field strength. Effective
action for instanton is derived in bilocal approximation and it is demonstrated
that stochastic background gluon fields are responsible for infra-red
(IR)stabilization of instantons. Comparison of obtained instanton size
distribution with lattice data is made.Comment: 3 pages, 2 figures. Talk given at 5th International Conference on
Quark Confinement and the Hadron Spectrum, Gargnano, Brescia, Italy, 10-14
Sep 200
Gell-Mann - Oakes - Renner relation in a magnetic field at finite temperature
In the first order of chiral perturbation theory the corrections to
and in a magnetic field at finite temperature have been
found. It was shown that they are shifted in such a manner that Gell-Mann -
Oakes - Renner relation remains valid under these conditions.Comment: 6 pages, LaTeX2
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