TY - JOUR
T1 - Ellipticity of photon emission from strongly magnetized hot QCD plasma
AU - Wang, Xinyang
AU - Shovkovy, Igor A.
AU - Yu, Lang
AU - Huang, Mei
N1 - Publisher Copyright:
© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.
PY - 2020/10/19
Y1 - 2020/10/19
N2 - By making use of an explicit representation for the imaginary part of the photon polarization tensor in terms of transitions between the Landau levels of light quarks, we study the angular dependence of direct photon emission from a strongly magnetized quark-gluon plasma. Because of the magnetic field, the leading order photon rate comes from the three processes of the zeroth order in the coupling constant αs: (i) the quark splitting (q→q+γ), (ii) the antiquark splitting (q¯→q¯+γ), and (iii) the quark-antiquark annihilation (q+q¯→γ). In a wide range of moderately high temperatures, Tmπ, and strong magnetic fields, |eB|mπ2, the direct photon production is dominated by the two splitting processes. We show that the Landau-level quantization of quark states plays an important role in the energy and angular dependence of the photon emission. Among other things, it leads to a nontrivial momentum dependence of the photon ellipticity coefficient v2, which takes negative values at small transverse momenta and positive values at large transverse momenta. The crossover between the two regimes occurs around kT≃|eB|. In application to heavy-ion collisions, this suggests that a large value of v2 for the direct photons could be explained in part by the magnetic field in the quark-gluon plasma.
AB - By making use of an explicit representation for the imaginary part of the photon polarization tensor in terms of transitions between the Landau levels of light quarks, we study the angular dependence of direct photon emission from a strongly magnetized quark-gluon plasma. Because of the magnetic field, the leading order photon rate comes from the three processes of the zeroth order in the coupling constant αs: (i) the quark splitting (q→q+γ), (ii) the antiquark splitting (q¯→q¯+γ), and (iii) the quark-antiquark annihilation (q+q¯→γ). In a wide range of moderately high temperatures, Tmπ, and strong magnetic fields, |eB|mπ2, the direct photon production is dominated by the two splitting processes. We show that the Landau-level quantization of quark states plays an important role in the energy and angular dependence of the photon emission. Among other things, it leads to a nontrivial momentum dependence of the photon ellipticity coefficient v2, which takes negative values at small transverse momenta and positive values at large transverse momenta. The crossover between the two regimes occurs around kT≃|eB|. In application to heavy-ion collisions, this suggests that a large value of v2 for the direct photons could be explained in part by the magnetic field in the quark-gluon plasma.
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U2 - 10.1103/PhysRevD.102.076010
DO - 10.1103/PhysRevD.102.076010
M3 - Article
AN - SCOPUS:85095131279
SN - 2470-0010
VL - 102
JO - Physical Review D
JF - Physical Review D
IS - 7
M1 - 076010
ER -