Polarization tensor of magnetized quark-gluon plasma at nonzero baryon density

Abstract

We derive a general expression for the absorptive part of the one-loop photon polarization tensor in a strongly magnetized quark-gluon plasma at nonzero baryon chemical potential. To demonstrate the application of the main result in the context of heavy-ion collisions, we study the effect of a nonzero baryon chemical potential on the photon emission rate. The rate and the ellipticity of photon emission are studied numerically as a function the transverse momentum (energy) for several values of temperature and chemical potential. When the chemical potential is small compared to the temperature, the rates of the quark and antiquark splitting processes (i.e., q → q + γ and q → q + γ, respectively) are approximately the same. However, the quark splitting gradually becomes the dominant process with increasing the chemical potential. We also find that increasing the chemical potential leads to a growing total photon production rate but has only a small effect on the ellipticity of photon emission. The quark-antiquark annihilation (q + q → γ) also contributes to the photon production, but its contribution remains relatively small for a wide range of temperatures and chemical potentials investigated.

Photon polarization tensor in a magnetized plasma: Absorptive part

“…It appears that the corresponding problem poses only a technical complication that can be overcome with a moderate effort. Such study is underway now [45]. A more difficult extension of the present work will be obtaining the real part of the photon polarization.…”

“…This is not surprising, of course, because the two processes are related by the charge conjugation symmetry. (Note, however, that the same is not true in a plasma at a nonzero chemical potential [45].) By taking this symmetry into account in Eq.…”

“…This is the consequence of the charge conjugation symmetry. It is expected, however, that both antisymmetric structures will be nonzero when µ = 0 [45].…”