# Isospin splitting of pion elliptic flow in relativistic heavy-ion collisions

## TL;DR

This paper investigates the difference in elliptic flow between positively and negatively charged pions in heavy-ion collisions, using an extended transport model to probe the quark matter equation of state and QCD phase structure.

## Contribution

It introduces the role of vector-isovector potentials in explaining pion elliptic flow splitting, linking it to the quark matter equation of state.

## Key findings

- Isospin splitting favors a strong vector-isovector interaction.
- The splitting serves as a probe for the quark matter equation of state.
- Provides insights into the QCD phase structure at finite baryon and isospin chemical potentials.

## Abstract

Based on the framework of an extended multiphase transport model with mean-field potentials in both the partonic phase and the hadronic phase, we explain the elliptic flow difference between $\pi^+$ and $\pi^-$ in the beam-energy scan program at the relativistic heavy-ion collider by incorporating the vector-isovector potential for quarks and antiquarks with different isospins. It is found that the isospin splitting of pion elliptic flow favors a strong vector-isovector interaction, and thus serves as a probe of the quark matter equation of state as well as the QCD phase structure at finite baryon and isospin chemical potentials.