Higher-order flow coefficients in dilepton emission from a magnetized hadronic medium

TL;DR

This paper investigates how strong magnetic fields in heavy-ion collisions induce higher-order azimuthal anisotropy in dilepton emission from a hot hadronic medium, revealing significant effects at low invariant masses linked to Landau-level quantization.

Contribution

It provides the first detailed analysis of higher-order flow coefficients in dilepton emission under magnetic fields, highlighting their dependence on Landau quantization and magnetic field strength.

Findings

Significant azimuthal anisotropy at low invariant masses due to magnetic fields.

Higher-order flow coefficients $v_4,v_6$ show oscillatory behavior linked to Landau levels.

Magnetic field effects are minimal at higher invariant masses.

Abstract

The study of dilepton emission from hot hadronic matter provides a unique probe of the medium properties in heavy-ion collisions. In strong magnetic fields expected in non-central collisions, the emission spectrum can develop anisotropic features. While the impact of a magnetic field on the dilepton emission rate has been explored, higher-order azimuthal anisotropy--characterized by flow coefficients beyond elliptic flow--remains an open question, particularly in the low invariant-mass region where medium effects are most pronounced. We investigate higher-order anisotropy in the dilepton emission rate from a magnetized hot hadronic medium. Our results reveal a continuous dilepton spectrum with strong Landau-cut contributions at low invariant masses due to the background magnetic field. The emission rate exhibits significant azimuthal-angle dependence in this region, characterized by flow coefficients $v_n$. Odd coefficients vanish by symmetry, while the elliptic flow $v_2$ is positive and oscillatory at low invariant masses--driven by Landau-level quantization of pions--but negligible at higher masses. Higher-order coefficients $v_4,v_6$ show similar trends, with notable structures at low masses and negligible values at higher masses. The transverse-momentum dependence increases with magnetic field strength, while temperature effects are minimal. Our findings demonstrate that the magnetic field induces significant higher-order azimuthal anisotropy in dilepton emission at low invariant masses, with $v_2,v_4,v_6$ exhibiting distinct oscillatory behavior linked to pion Landau quantization. This resolves the gap in understanding the anisotropic response of dilepton emission in magnetized media. The results highlight dileptons as sensitive probes of magnetic-field effects in heavy-ion collisions, offering new avenues to constrain field strengths and hadronic dynamics in the QGP.