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arXiv 1005.1689hep-phnucl-th
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介子环修正下有限温度手征的恢复

Chiral restoration at finite temperature with meson loop corrections

Seung-il Nam, Chung-Wen Kao

摘要:

我们研究了在有限温度(T)和零夸克化学势(超过手征极限)下N_{c} =3和N_{f} =2的QCD手征恢复模式,表明手征对称性破缺是明显的.为此,我们采用了味SU(2)扇区的瞬子真空组态和Harrington-Shepard Caloron来修正作为T函数的相关瞬子参数。相应于1/ N_{c}修正的介子环修正(MLC)也被考虑到再现适当的手征序参量的m_{q}依赖性。我们计算手征缩合物作为T和/或m_{q}的函数。从数值计算,我们观察到MLC发挥重要作用,有一个正确的普适性类行为的手征恢复模式在这个框架中,取决于m_{q}:二级相变的手征极限,m_{q} =0和交叉m_{q} >0。没有MLC,所有的恢复模式是交叉的,由于简单的鞍点近似。结果表明,在手征极限下,T ^χ_{c}=159 MeV,当m_{q} =(5,10,15)MeV时,T^χ_{c}=(177,186,196)MeV。

英文摘要:

We investigate chiral-restoration patterns of QCD for N_{c}=3 and N_{f}=2 at finite temperature (T) and zero quark-chemical potential beyond the chiral limit, indicating the explicit chiral-symmetry breaking. To this end, we employ the instanton-vacuum configuration for the flavor SU(2) sector and the Harrington-Shepard caloron for modifying relevant instanton parameters as functions of T. The meson-loop corrections (MLC), which correspond to 1/N_{c} corrections, are also taken into account to reproduce appropriate m_{q} dependences of chiral order parameters. We compute chiral condensate as a function of T and/or m_{q}. From the numerical calculations, we observe that MLC play an important role to have a correct universality-class behavior of chiral-restoration patterns in this framework, depending on m_{q}: Second-order phase transition in the chiral limit, m_{q}=0 and crossover for m_{q}>0. Without MLC, all the restoration patterns are crossover, due to simple saddle-point approximations. It turns out that T^χ_{c}=159 MeV in the chiral limit and T^χ_{c}=(177,186,196) MeV for m_{q}=(5,10,15) MeV, using the phenomenological choices for the instanton parameters at T=0.

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