# Impact of magnetic-field fluctuations on measurements of the chiral magnetic effect in collisions of isobaric nuclei

## TL;DR

This study uses a transport model to analyze electromagnetic fields in isobaric nuclear collisions, highlighting how magnetic field strength and deformation influence measurements of the chiral magnetic effect.

## Contribution

It demonstrates the impact of nuclear deformation and collision geometry on magnetic field correlations relevant to the chiral magnetic effect in isobaric collisions.

## Key findings

- Magnetic fields are stronger in Ru+Ru than Zr+Zr collisions.
- Nuclear deformation affects magnetic field correlation especially in peripheral events.
- Correlation with spectator plane provides cleaner signals for the chiral magnetic effect.

## Abstract

We investigate the properties of electromagnetic fields in isobaric $_{44}^{96}\textrm{Ru}+\,_{44}^{96}\textrm{Ru}$ and $_{40}^{96}\textrm{Zr}+\,_{40}^{96}\textrm{Zr}$ collisions at $\sqrt{s}$ = 200 GeV by using a multiphase transport model, with special emphasis on the correlation between magnetic field direction and participant plane angle $\Psi_{2}$ (or spectator plane angle $\Psi_{2}^{\rm SP}$), i.e. $\langle{\rm cos}\ 2(\Psi_B - \Psi_{2})\rangle$ [or $\langle{\rm cos}\ 2(\Psi_B - \Psi_{2}^{\rm SP})\rangle$]. We confirm that the magnetic fields of $_{44}^{96}\textrm{Ru}+\,_{44}^{96}\textrm{Ru}$ collisions are stronger than those of $_{40}^{96}\textrm{Zr}+\,_{40}^{96}\textrm{Zr}$ collisions due to their larger proton fraction. We find that the deformation of nuclei has a non-negligible effect on $\langle{\rm cos}\ 2(\Psi_B - \Psi_{2})\rangle$ especially in peripheral events. Because the magnetic-field direction is more strongly correlated with $\Psi_{2}^{\rm SP}$ than with $\Psi_{2}$, the relative difference of the chiral magnetic effect observable with respect to $\Psi_{2}^{\rm SP}$ is expected to be able to reflect much cleaner information about the chiral magnetic effect with less influences of deformation.