分类： 物理学 >> 核物理学 提交时间： 2016-09-06
摘要： We study microscopic processes responsible for chirality flips in the thermal bath of Quantum Chromodynamics at finite temperature and zero baryon chemical potential. We focus on the temperature range where the crossover from chirally broken phase to quark-gluon plasma takes place, namely T≃(150,200) MeV. The processes we consider are quark-quark scatterings mediated by collective excitations with the quantum number of pions and σ-meson, hence we refer to these processes simply as \sugg{to} one-pion (one-σ) exchange\sugg{s}. We use a Nambu-Jona-Lasinio model to compute equilibrium properties of the thermal bath, as well as the relevant scattering kernel to be used in the collision integral to estimate the chiral relaxation time τ. We find τ≃0.1÷1 fm/c around the chiral crossover.
分类： 物理学 >> 核物理学 提交时间： 2016-09-02
摘要： We investigate the effect of the inverse magnetic catalysis (IMC) on the charged ρ meson condensation at finite temperature in the framework of the Nambu--Jona-Lasinio model, where mesons are calculated to the leading order of 1/Nc expansion by summing up infinity quark-loops. IMC for chiral condensate has been considered in three different ways, i.e. fitting Lattice data, using the running coupling constant and introducing the chiral chemical potential, respectively. It is observed that, with no IMC effect included, the critical magnetic field eBc for charged ρ condensation increases monotonically with the temperature. However, including IMC substantially affects the polarized charged ρ condensation around the critical temperature Tc of chiral phase transition, the critical magnetic field eBc for charged ρ condensation decreases with the temperature firstly, reaches to a minimum value around Tc, then increases with the temperature. Our calculation indicates that the charged ρ condensation can exist in the temperature region of 1−1.5Tc with critical magnetic field eBc∼0.15−0.3GeV2, which suggests that high temperature superconductor might be created through non-central heavy ion collisions at LHC energies. We also show that a growing electric conductivity in early stage of non-central heavy-ion collisions substantially delays the decay of strong magnetic field, which is helpful for the formation of the high temperature superconductor.
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