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

D. Bala, S. Ali, A. Francis, G. Jackson, O. Kaczmarek, T. Ueding

Research output: Contribution to journalConference articlepeer-review


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 ρT (ω = |(Equation presented)|, (Equation presented)). One can also calculate the photon production rate from the difference between ρT (ω, (Equation presented)) (transverse) and ρL (ω, (Equation presented)) (longitudinal) projections, as ρL vanishes on the photon point. Because the UV part of ρT - ρL is suppressed, the corresponding Euclidean correlator receives most of its contribution from the IR part. We calculate the T - L correlator on Nf = 2 + 1 flavour HISQ configurations with ml = ms/5 at temperature of about 1.15 Tpc (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.

Original languageEnglish
Article number169
JournalProceedings of Science
StatePublished - 6 Apr 2023
Event39th International Symposium on Lattice Field Theory, LATTICE 2022 - Bonn, Germany
Duration: 8 Aug 202213 Aug 2022


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