论文标题
$ n_f $ = 2+1 QCD的dirac特征值频谱使用HISQ Fermions朝手性限制
Dirac Eigenvalue spectrum of $N_f$=2+1 QCD towards the chiral limit using HISQ fermions
论文作者
论文摘要
我们利用特征值滤波技术与模式数的随机估计结合来确定特征值频谱。 （2 + 1）-Fravor QCD的仿真使用高度改进的交错夸克（HISQ/TROE）在$n_τ$ = 8个晶格上具有5到7的宽高比$n_σ/n_τ$范围为5到7。从$ m_ {s}^{\ rm phy}/40 $到$ m_ {s}^{\ rm phy}/160 $，对应于pion mass $m_π$在连续限制下从110 meV到55 mev。我们通过从特征值滤波方法获得的特征值来计算手性冷凝物和$χ_π -χ_δ$。我们将这些结果与使用随机“噪声矢量”方法进行反转的可观测值进行了比较。我们发现这些方法产生一致的结果。此外，我们还研究了零特征值的dirac特征值密度的夸克质量和温度依赖性，以获得有关$ u_a（1）$对称破坏QCD中的更多见解。
We utilize the eigenvalue filtering technique combined with the stochastic estimate of the mode number to determine the eigenvalue spectrum. Simulations of (2 + 1)-flavor QCD are performed using the Highly Improved Staggered Quarks (HISQ/tree) action on $N_τ$ = 8 lattices with aspect ratios $N_σ/N_τ$ ranging from 5 to 7. The strange quark mass is fixed to its physical value $m_{s}^{\rm phy}$, and the light quark masses $m_{l}$ are varied from $m_{s}^{\rm phy}/40$ to $m_{s}^{\rm phy}/160$ which correspond to pion mass $m_π$ ranging from 110 MeV to 55 MeV in the continuum limit. We compute the chiral condensate and $χ_π - χ_δ$ through the eigenvalue spectrum obtained from the the eigenvalue filtering method. We compare these results with those obtained from a direct calculation of the observables which involves inversions of the fermion matrix using the stochastic "noise vector" method. We find that these approaches yield consistent results. Furthermore, we also investigate the quark mass and temperature dependences of the Dirac eigenvalue density at zero eigenvalues to gain more insights about the $U_A(1)$ symmetry breaking in QCD.
