Speaker
Description
In non-central heavy-ion collisions, ultra strong magnetic fields can be generated by the nuclear fragments. The fluctuations of these electromagnetic fields, originating from event-by-event variations in the initial nucleon distributions, were proposed in Refs. [1, 2]. In this talk, I present our recent study of the impact of the electromagnetic-field fluctuations on the charge-dependent flow fluctuations. We incorporate the iEBE-VISHINU model along with Maxwell equations including a finite electrical conductivity in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV [3]. The results show that fluctuations of in-plane and out-of-plane electromagnetic-field components, $E_x$, $E_y$, $B_x$ and $B_y$, could induce fluctuations in the charge splitting of the directed flow, $\Delta v_1=v_1^+ - v_1^-$, and in the out-of-plane observable $\Delta a_1=a_1^+ - a_1^-$. The magnitude of $\Delta v_1$ fluctuations is found to be comparable to the average $\Delta v_1$ reported in experiments [4], and this result therefore provides another important experimentally accessible way to study the electromagnetic-field effects in the quark-gluon plasma.
[1] Deng W-T, Huang X-G. Event-by-event generation of electromagnetic fields in heavy-ion collisions. Phys Rev. C 2012;85(4):044907.
[2] Bzdak A, Skokov V. Event-by-event fluctuations of magnetic and electric fields in heavy ion collisions. Phys Lett B. 2012;710(1):171.
[3] Umut Gursoy, Charge-dependent flow induced by magnetic and electric fields in heavy-ion collisions, Phys. Rev. C 98 (2018) 5, 055201.
[4] the STAR collaboration, Observation of the electromagnetic field effect via charge-dependent directed flow in heavy-ion collisions at the Relativistic Heavy Ion Collider, Phys. Rev. X 14 , 011028 (2024).
[5] L.J. Li, D.Y. Shen, and X. L. Zhao, Probing event-by-event electromagnetic field fluctuations via charge-dependent flow fluctuations in heavy-ion collisions, preparing.
