测试QCD热力学中的强同位旋破缺效应
Testing strong isospin breaking effects in QCD thermodynamics
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中文总结 AI 辅助
针对QCD热力学中强同位旋破缺效应，采用物理夸克质量的$N_f=1+1+1$动力学改进交错费米子模拟，计算夸克凝聚差、伪临界温度、状态方程及守恒荷涨落，并与$N_f=2+1$结果对比。
中文摘要 AI 辅助
大多数现代格点QCD计算将轻夸克质量视为简并的，即设定$m_u=m_d$，这一选择虽然不物理，但提高了计算效率并降低了模拟和分析的复杂性。对于许多可观测量，与这种简化相关的系统误差预计可以忽略不计，因为$\u0394m_{ud}=m_d-m_u$远低于QCD标度。迄今为止，格点研究已考察了强同位旋破缺（SIB）在强子质量劈裂中的作用，但热力学可观测量中的SIB效应仅在具有非物理重夸克的交叉温度研究中被探讨。受近期重离子碰撞实验中带电与中性K介子丰度比意外偏大观测的启发，我们通过使用动力学改进交错费米子，对具有物理夸克质量的三个非简并味（$N_f=1+1+1$）计算可观测量，从而研究SIB在QCD热力学中的效应。具体而言，我们考察$u$-和$d$-夸克凝聚体之间的差异，并提取伪临界温度、状态方程和守恒荷涨落，与标准$N_f=2+1$模拟的结果进行比较。
英文摘要
Most modern lattice QCD calculations take the masses of the light quarks to be degenerate, setting $m_u=m_d$, a choice that, while not physical, increases computational efficiency and lowers the complexity of simulations and analysis. For many observables, the systematic error associated with this simplification is expected to be negligible, as $Δm_{ud}=m_d-m_u$ is significantly below the QCD scale. So far lattice studies have examined the role of strong isospin breaking (SIB) in hadron mass splittings, but SIB effects in thermodynamic observables have only been studied in terms of the crossover temperature with unphysically heavy quarks. Motivated by the recent observation of an unexpectedly large ratio between the abundances of charged versus neutral kaons in heavy-ion collision experiments, we investigate the effects of SIB in QCD thermodynamics by computing observables for three non-degenerate flavors ($N_f=1+1+1$) with physical quark masses using dynamical improved staggered fermions. In particular, we investigate the difference between the $u$- and $d$-quark condensates and extract the pseudocritical temperature, the equation of state, and conserved-charge fluctuations, comparing results to standard $N_f=2+1$ simulations.
