Photon radiation induced by rescattering in strong-interacting medium with a magnetic field

TL;DR

This work analyzes how a background magnetic field in a quark-gluon plasma alters medium-induced photon radiation from a high-energy jet in relativistic heavy-ion collisions. It combines the GLV opacity expansion to first order with a weak-field expansion of the charged-scalar propagator derived from Schwinger's method, yielding magnetic-field–dependent photon emission rates and energy loss. Numerically, the study finds a slight suppression of photon yields and a modest reduction of jet electromagnetic energy loss as the magnetic field strengthens, with the effect being more pronounced for softer photons and diminishing for harder jets. These results provide a theoretical basis for comparing direct photon yields across collision systems that differ in magnetic-field strength but have similar bulk properties, aiding interpretation of photon observables in magnetized QGP environments.

Abstract

The photon radiation induced by rescattering in a magnetized medium is investigated in relativistic heavy-ion collisions. Within the high-energy limit, the photon emission rate and the associated electromagnetic energy loss are derived using the Gyulassy-Levai-Vitev formalism at first order in opacity, for a quark jet propagating a quark-gluon plasma under a background magnetic field. Quantitative analysis shows a slight suppression of the overall photon radiation over a broad range of jet energies in this process. This reduction in photon yield consequently leads to a moderate decrease in the electromagnetic energy loss of the jet. Our results contribute to a better understanding of the electromagnetic properties of strongly interacting matter in high-energy nucleus-nucleus collisions and motivate experimental comparison of photon yields from quark-gluon plasma with similar properties but distinct magnetic field strengths.

Figures (10)

• Figure 1: Self-quenching photon radiation diagram as the direct contributing to the zeroth order in opacity.
• Figure 2: Single scattering photon radiation diagrams as the direct contributing to the first order in opacity.
• Figure 3: Double Born scattering photon radiation diagrams as the contact-limit contributing to the first order in opacity.
• Figure 4: Comparison of photon yields as a function of $x$ for different jet initial energies $E$ with and without magnetic field.
• Figure 5: Photon yield ratios as a function of $x$ with to without magnetic field for different jet initial energies $E$.