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

Abstract

We investigate the properties of electromagnetic fields in isobaric 4496Ru+4496Ru and 4096Zr+4096Zr collisions at s=200GeV by using a multiphase transport model with special emphasis on the correlation between magnetic-field direction and participant plane angle Ψ2 (or spectator plane angle Ψ2SP), i.e., (cos2(ΨB-Ψ2)) [or (cos2(ΨB-Ψ2SP))]. We confirm that the magnetic fields of 4496Ru+4496Ru collisions are stronger than those of 4096Zr+4096Zr collisions due to their larger proton fraction. We find that the deformation of nuclei has a non-negligible effect on (cos2(ΨB-Ψ2)) especially in peripheral events. Because the magnetic-field direction is more strongly correlated with Ψ2SP than with Ψ2, the relative difference of the chiral magnetic effect observable with respect to Ψ2SP is expected to be able to reflect much cleaner information about the chiral magnetic effect with less influences of deformation.