On the nature of the finite-temperature transition in QCD
On the nature of the finite-temperature transition in QCD
复制标题
QCD 有限温度转变的本质
DOI：
10.1088/1126-6708/2003/08/029
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发表时间：
2003
影响因子：
5.4
通讯作者：
E. Vicari
中科院分区：
文献类型：
--
作者：
Agostino Butti;A. Pelissetto;E. Vicari
我们研究了Nf无质量味QCD中有限温度跃迁的性质。普适性参数表明，一个连续的相变可能存在，只有当有一个稳定的不动点在三维？4以破缺模式为特征的理论[SU（Nf）L？SU（Nf）R]/（Nf）V？SU（Nf）V/（Nf）V或[U（Nf）L？U（Nf）R]/U（1）V？U（Nf）V/U（1）V，如果U（1）A对称性在Tc处有效恢复。为了确定这些不动点？4理论，我们利用一个三维微扰的方法，其中物理量的重整化四次耦合的权力扩大。我们计算微扰膨胀的？-函数到六个循环并确定它们的高阶行为。除了Nf = 2对应于破缺模式SO（4）？SO（3）.因此，有限温度相变QCD是一阶Nf？3.只有当Nf = 2时才允许连续相变。但是，由于具有破缺模式的理论[U（2）L？U（2）R]/U（1）？U（2）V/U（1）没有稳定的不动点，只有当U（1）A对称性的有效破缺足够大时，跃迁才是连续的。
We investigate the nature of the finite-temperature transition in QCD with Nf massless flavors. Universality arguments show that a continuous phase transition may exist only if there is a stable fixed point in the three-dimensional ?4 theory characterized by the symmetry-breaking pattern [SU(Nf)L?SU(Nf)R]/(Nf)V?SU(Nf)V/(Nf)V, or [U(Nf)L?U(Nf)R]/U(1)V?U(Nf)V/U(1)V if the U(1)A symmetry is effectively restored at Tc. In order to determine the fixed points of these ?4 theories, we exploit a three-dimensional perturbative approach in which physical quantities are expanded in powers of renormalized quartic couplings. We compute the perturbative expansion of the ?-functions to six loops and determine their large-order behavior. No stable fixed point is found, except for Nf = 2 corresponding to the symmetry-breaking pattern SO(4)?SO(3). Therefore, the finite-temperature phase transition in QCD is of first order for Nf ? 3. A continuous phase transition is allowed only for Nf = 2. But, since the theory with symmetry-breaking pattern [U(2)L?U(2)R]/U(1)?U(2)V/U(1) does not have stable fixed points, the transition can be continuous only if the effective breaking of the U(1)A symmetry is sufficiently large.