共查询到20条相似文献,搜索用时 9 毫秒
1.
We calculate a correction to the effective electromagnetic current at low energies, induced by a heavy-quark loop, and determine the analytic structure of the vacuum polarization function at small q 2, for which an explicit expression is given to the O(α s 3 ) order of perturbation theory. Implications to the high-precision analysis of experimental data on heavy-quark production in e + e ? annihilation are discussed. 相似文献
2.
We investigate the thermal behaviour of gluon and chiral condensates within an effective Lagrangian of pseudoscalar mesons coupled to a scalar glueball. This Lagrangian mimics the scale and chiral symmetries of QCD. 相似文献
3.
We study the properties of mixed quark–gluon condensate at finite temperature and chemical potential in the framework of global color symmetry model. In comparing with the quark condensate, we confirm that both of these condensates give the same information about chiral phase transition. We also find that the ratio of these two condensates is insensitive to the temperature T and the chemical potential μ, which supports the conclusion obtained recently by the authors using quenched lattice QCD. 相似文献
4.
《Physics letters. [Part B]》1988,201(1):117-122
The Landau gauge gluon propagator at finite temperature above and below the deconfinement transition is measured using lattice Monte Carlo simulation. The color electric and magnetic masses are determined. The most striking result of the calculation is that the time component of the gluon field appears to acquire a vacuum expected value in the deconfined region. 相似文献
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D. Müller M. Buballa J. Wambach 《The European Physical Journal A - Hadrons and Nuclei》2013,49(8):1-14
We investigate the phases of dense QCD matter at finite temperature with Dyson-Schwinger equations for the quark propagator for N f = 2 + 1 flavors. For the gluon propagator we take a fit to quenched lattice data and add quark-loop effects perturbatively in a hard-thermal-loop-hard-dense-loop approximation. We consider 2SC and CFL-like pairing with chiral up and down quarks and massive strange quarks and present results for the condensates and the phase diagram. We find a dominant CFL phase at chemical potentials larger than 500-600MeV. At lower values of the chemical potential we find a 2SC phase, which also exists in a small band at higher temperatures for larger chemical potentials. With values of 20–30 MeV, the critical temperatures to the normal phase turn out to be quite small. 相似文献
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The single-loop approximation is used to calculate a gluon condensate in an external spherically symmetric non-Abelian chromomagnetic
field.
Moscow Institute of Radio Engineering, Electronics, and Automation. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii,
Fizika, No. 7, pp. 18–22, July, 1997. 相似文献
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10.
Dieter Gromes 《Physics letters. [Part B]》1982,115(6):482-486
We consider the influence of the gluon condensate in QCD on the energy levels of quarkonia, taking into account the x-dependence of 〈ω|:Gμva(x) Gaμv(0):|ω〉. The modification compared to earlier approaches which approxim ated the above vacuum expectation value by a constant is quite sizeable; for the b?b system we find that the effect can be essentially described in terms of a local potential. 相似文献
11.
Instanton liquid in heated and strongly interacting matter is studied using the variational principle. The dependence of the instanton liquid density (gluon condensate) on the temperature and the quark chemical potential is determined under the assumption that, at finite temperatures, the dominant contribution is given by an ensemble of calorons. The respective one-loop effective quark Lagrangian is used. 相似文献
12.
R. V. Gavai 《Physics letters. [Part B]》1984,140(5-6):397-402
Using the pseudo-fermion Monte Carlo method we investigate the chiral and the deconfinement phase transitions in the SU(3) gauge theory with dynamical staggered fermions on a 63 × 2 lattice. The energy density of the gluonic sector εG, the average thermal Wilson loop |L| and the order parameter
are found to have a rapid variation in the same range of β (=6/g2). The variation is similar to that observed in the quenched theory but is at a smaller value of β. 相似文献
13.
A.D. Linde 《Nuclear Physics B》1983,216(2):421-445
In this paper we study kinetics of the first-order phase transitions in gauge theories with spontaneous symmetry breaking. A general theory of the decay of the metastable phase (false vacuum) at a finite temperature is developed. A number of concrete examples are considered, which will make it possible to study kinetics of phase transitions in a wide class of theories without complicated computer calculations. 相似文献
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15.
A complete high temperature expansion is carried out for the QCD gluon self-energy diagram in the general covariant gauge by using thermo field dynamics. Using the result we clarify the gauge dependence down to the logarithmic term. 相似文献
16.
B. G. Zakharov 《JETP Letters》2004,80(2):67-72
We study the influence of finite kinematic boundaries on the induced gluon radiation from a fast quark in a finite size quark-gluon plasma. The calculations are carried out for fixed and running coupling constant. We find that, for running coupling constant, the kinematic correction to the radiative energy loss is small for quark energy ?5 GeV. Our results differ both analytically and numerically from that obtained by the GLV group [6]. The effect of the kinematic cutoffs is considerably smaller than reported in [6]. 相似文献
17.
《Physics letters. [Part B]》1987,197(3):403-404
The gluon condensate of dimension 4 is shown to stay unchanged through the deconfining phase transition. 相似文献
18.
R. A. Bertlmann C. A. Dominguez M. Loewe M. Perrottet E. de Rafael 《Zeitschrift fur Physik C Particles and Fields》1988,39(2):231-240
The dimension four gluon condensate and the dimension six four-quark condensate are estimated with the help of FESR by analyzing the ρ-meson channel. We find that the first is a factor 2–5 and the second is (in absolute value) a factor 5–8 larger than the corresponding “standard values”. We have checked our results by the “heat evolution test” of Gauss transforms. They turn out to be consistent whereas the “standard values” are not. 相似文献
19.
F. R. Graziani 《Zeitschrift fur Physik C Particles and Fields》1987,33(3):397-405
Using massive gauge invariant QCD we show explicity how power like corrections to \(\Pi _{\mu v} \left( q \right) = i\int {dx} e^{iq'x} \left\langle {0\left| {j_\mu ^{em} \left( x \right)\bar j_v^{em} \left( 0 \right)} \right|0} \right\rangle \) arise. Using our result for the 1/q 4 contribution, a one to one correspondence is made between the gluon condensate and the effective gluon mass. By relating this mass to, \(\langle 0|\frac{{\alpha _s }}{\pi }G_{\mu v}^2 |0\rangle \) a value ofm gluon=750 MeV is found at ?q 2=10 GeV2. In addition, within the context of dimensional regularization, a new technique for evaluating two loop momentum integrals with massive propagators is introduced. This method is a derivative of the Mellin transform technique that was applied to ladder diagrams in the days of Reggeisation. 相似文献
20.
Nonperturbative QCD vacuum with two light quarks at finite temperature was studied in a hadron resonance-gas model. Temperature dependences of the quark and gluon condensates in the confined phase were obtained. It is shown that the quark condensate and one-half (chromoelectric component) of the gluon condensate are evaporated at the same temperature corresponding to the quark-hadron phase transition. With allowance for the temperature shift of hadron masses, the critical temperature was found to be T c ?190 MeV. 相似文献