Higher-order flow coefficients of source-level dilepton emission in a magnetized hadronic medium

Abstract

The study of dilepton emission from hot hadronic matter provides a unique probe of the properties of strongly interacting medium created in heavy-ion collisions. In non-central collisions, the presence of magnetic fields can induce anisotropic features in the emission spectrum. While the impact of a magnetic field on the dilepton emission rate has extensively studied, the detailed higher-order azimuthal anisotropies of the emission rate--characterized by flow coefficients beyond elliptic flow-- remain an open question, particularly in the low invariant-mass region where magnetic-field-induced medium effects are expected to be most pronounced. Here, we investigate higher-order azimuthal anisotropies of the source-level thermal dilepton emission 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 source-level flow coefficients $v_{2,4,6}$. The odd-order coefficients vanish due to symmetry. The elliptic flow coefficient $(v_2)$ is positive and exhibits an oscillatory structure at low invariant masses--driven by Landau-level quantization of pions, but negligible at higher masses. Similar behavior is observed for the higher-order coefficients $v_4$ and $v_6$ with notable structures at low masses and negligible values at higher masses. The results highlight dileptons as sensitive probes of magnetic-field effects in heavy-ion collisions, offering new avenues to constrain the strength of magnetic fields and unravel the properties and dynamics of hot hadronic matter.

Comments: 15 pages, 6 figures