Speaker
Description
Strong electromagnetic (EM) field in heavy-ion collisions could leave an imprint on the final-state particles. Due to such EM field, particles and anti-particles with opposite charges will receive opposite contributions to their rapidity-odd directed flow. Here, we present the charge-dependent measurements of $dv_1/d\mathsf{y}$ near midrapidity for $\pi^{\pm}$, $K^{\pm}$, and $p(\bar{p})$ in Au+Au and isobar collisions at $\sqrt{s_{NN}}=$ 200 GeV, and in Au+Au at 27 GeV. A clear difference in $dv_1/dy$ between positively and negatively charged hadrons ($\Delta dv_1/dy$) has been observed, and the $\Delta dv_1/d\mathsf{y}$ changes from positive in central collisions to negative in peripheral collisions for kaons and protons. While the results in central events can be explained by $u$ and $d$ quarks transported from the initial-state nuclei, those in peripheral events reveal contributions from the Faraday induction and Coulomb effect for the first time in heavy-ion collisions.
| Theory / experiment | Experiment |
|---|---|
| Group or collaboration name | STAR |
