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arXiv · 2212.11509

Photon production rate from Transverse-Longitudinal ($T-L$) mesonic correlator on the lattice

Dibyendu Bala·Sajid Ali·Anthony Francis·Greg Jackson·Olaf Kaczmarek·Tristan Ueding
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Abstract

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.

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Dibyendu Bala, Sajid Ali, Anthony Francis, Greg Jackson, Olaf Kaczmarek, Tristan Ueding. 2023-02-17. Photon production rate from Transverse-Longitudinal ($T-L$) mesonic correlator on the lattice. https://doi.org/10.22323/1.430.0169

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