论文标题
从晶格上的横向长义（$ t-l $）的光子生产率
Photon production rate from Transverse-Longitudinal ($T-L$) mesonic correlator on the lattice
论文作者
论文摘要
来自QGP的热光子提供了有关血浆成分之间相互作用的重要信息。来自热平衡系统的光子生产速率与横向光谱函数$ρ_T（ω= | \ vec k |，\ vec k）$成正比。人们还可以从$ρ_t（ω，\ vec k）$（横向）和$ρ_l（ω，\ vec k）$（纵向）投影中计算出光子生产率，为$ρ_l$ $ρ_l$在光子点上消失。由于$ρ_T-ρ_l$的紫外线部分被抑制了，因此相应的欧几里得相关器从红外部件获得了大部分贡献。我们计算$ t \！ - \！l $相关器，$ n_f = 2+1 $ flues hisq配置，$ m_l = m_l = m_s/5 $在约1.15美元的温度下，t_ {pc} $（220 mev）。我们已经使用了两个Ansätze来用于光谱函数：1）与OPE膨胀一致的多项式连接的多项式和2）水力启发的光谱函数。我们还应用了Backus-Gilbert方法来估计光谱函数。将所有这些不同的方法合并以估计光子的生产率。
Thermal photons from the QGP provide important information about the interaction among plasma constituents. The photon production rate from a thermally equilibrated system is proportional to the transverse spectral function $ρ_T(ω=|\vec k|, \vec k)$. One can also calculate the photon production rate from the difference between $ρ_T(ω,\vec k)$ (transverse) and $ρ_L(ω,\vec k)$ (longitudinal) projections, as $ρ_L$ vanishes on the photon point. Because the UV part of $ρ_T-ρ_L$ is suppressed, the corresponding Euclidean correlator receives most of its contribution from the IR part. We calculate the $T\!-\!L$ correlator on $N_f=2+1$ flavour HISQ configurations with $m_l=m_s/5$ at temperature of about $1.15\,T_{pc}$ (220 MeV). We have used two ansätze for the spectral function: 1) A polynomial connected to the UV region consistent with OPE expansion and 2) a hydro-inspired spectral function. We have also applied the Backus-Gilbert method to estimate the spectral function. All these different approaches are combined to estimate the photon production rate.
