Dynamic Calculations of Magnetic Field and Implications on Spin Polarization and Spin Alignment in Heavy Ion Collisions

TL;DR

This study numerically models the time evolution of magnetic fields in heavy-ion collisions to assess their impact on spin polarization and alignment, revealing limited effects on global polarization but potential influence on vector mesons.

Contribution

It introduces a finite-difference time-domain numerical approach to simulate magnetic fields in heavy-ion collisions with time-dependent conductivity.

Findings

Magnetic fields may not last long enough to affect global spin polarization.

Magnetic fields could influence spin alignment of vector mesons.

Results vary across collision energies from 7.7 to 200 GeV.

Abstract

Magnetic field plays a crucial role in various novel phenomena in heavy-ion collisions. We solve the Maxwell equations numerically in a medium with time-dependent electric conductivity by using the Finite-Difference Time-Domain (FDTD) algorithm. We investigate the time evolution of magnetic fields in two scenarios with different electric conductivities at collision energies ranging from $\sqrt{s_\text{NN}}=$ 7.7 to 200 GeV. Our results suggest that the magnetic field may not persist long enough to induce a significant splitting between the global spin polarizations of $\Lambda$ and $\bar{\Lambda}$ at freeze-out stage. However, our results do not rule out the possibility of the magnetic field influencing the spin (anti-)alignment of vector mesons.