论文标题

软壁ADS-QCD模型中的茶动力学

Pion dynamics in a soft-wall AdS-QCD model

论文作者

Cao, Xuanmin, Baggioli, Matteo, Liu, Hui, Li, Danning

论文摘要

伪石模式出现在许多物理系统中,并显示强大的通用功能。首先,他们的质量$ m $服从所谓的Gell-Mann-Oakes-Renner(GMOR)关系$ f^2 \,m^2 \,m^2 = h \,\barσ$,带有$ f $ the Goldstone刚度,$ h $ $ h $ the explicit Breaking Breaking Scale和$ \barσ$ $ \barσ$自发性浓缩物。最近,已经证明他们的阻尼$ω$被限制为遵循关系$ω= m^2d_φ$,其中$d_φ$是纯粹自发相的金石扩散率。培来是伪金石模式的最范式的例子,它们与QCD中的手性对称性断裂有关。在这项工作中,我们考虑了一个自下而上的软壁ADS-QCD模型,其$ {\ rm {su}}(2)_l \ times {\ rm {su}}(2)_r $对称性,我们研究了相关的pseudo-goldstone模态的性质。特别是,我们对存在耗散的分散性关系进行了详细的研究,即夸克质量引起的显式断裂和临界点附近的动力学的作用。利用全息模型提供的微观信息,我们为有效描述中出现的所有系数提供了定量预测。特别是,我们估计动力学参数的有限温度行为$ \ mathfrak {r^2} $定义为Goldstone扩散性$d_φ$与触发衰减常数$ d_a $之间的评分。有趣的是,我们观察到与零温度限制在手性扰动理论中计算的值$ \ mathfrak {r^2} = 3/4 $的重要偏差。

Pseudo-Goldstone modes appear in many physical systems and display robust universal features. First, their mass $m$ obeys the so-called Gell-Mann-Oakes-Renner (GMOR) relation $f^2\,m^2=H\,\barσ$, with $f$ the Goldstone stiffness, $H$ the explicit breaking scale and $\barσ$ the spontaneous condensate. More recently, it has been shown that their damping $Ω$ is constrained to follow the relation $Ω=m^2 D_φ$, where $D_φ$ is the Goldstone diffusivity in the purely spontaneous phase. Pions are the most paradigmatic example of pseudo-Goldstone modes and they are related to chiral symmetry breaking in QCD. In this work, we consider a bottom-up soft-wall AdS-QCD model with broken ${\rm{SU}}(2)_L \times {\rm{SU}}(2)_R$ symmetry and we study the nature of the associated pseudo-Goldstone modes -- the pions. In particular, we perform a detailed investigation of their dispersion relation in presence of dissipation, of the role of the explicit breaking induced by the quark masses and of the dynamics near the critical point. Taking advantage of the microscopic information provided by the holographic model, we give quantitative predictions for all the coefficients appearing in the effective description. In particular, we estimate the finite temperature behavior of the kinetic parameter $\mathfrak{r^2}$ defined as the ration between the Goldstone diffusivity $D_φ$ and the pion attenuation constant $D_A$. Interestingly, we observe important deviations from the value $\mathfrak{r^2}=3/4$ computed in chiral perturbation theory in the limit of zero temperature.

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