# Quark Matter 2018

13-19 May 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## Virtual photon polarization and dilepton anisotropy in relativistic heavy-ion collisions

15 May 2018, 17:00
2h 40m
First floor and third floor (Palazzo del Casinò)

### First floor and third floor

#### Palazzo del Casinò

Poster Chirality, vorticity and polarisation effects

### Speaker

Enrico Speranza (Frankfurt University)

### Description

We present a general framework for studying the angular anisotropy of dileptons produced from polarized virtual photons in relativistic heavy-ion collisions. The spin-anisotropy coefficients characterizing the angular distribution of the dilepton final state are introduced and their dependence on the medium evolution via flow velocity and temperature profiles is obtained. We illustrate these effects in dilepton production from quark-antiquark annihilation in the QGP phase and $\pi^+ \pi^-$ annihilation in the hadronic phase for a static uniform medium and for a longitudinally expanding system. It is shown that the anisotropy coefficients are in general non-zero in a thermalized medium, and depend on the flow of the medium as well as on the transverse momentum and invariant mass of the virtual photon. The present framework can be easily implemented in a realistic hydrodynamic simulation of relativistic heavy-ion collisions in order to study the effect of non-trivial medium properties on dilepton anisotropy.

Content type Theory Presenter name already specified

### Primary authors

Enrico Speranza (Frankfurt University) Amaresh Jaiswal (NISER) Bengt Friman (GSI)