Azimuthally fluctuating magnetic field and its impacts on observables in   heavy-ion collisions
  The heavy-ion collisions can produce extremely strong transient magnetic and electric fields. We study the azimuthal fluctuation of these fields and their correlations with the also fluctuating matter geometry (characterized by the participant plane harmonics) using event-by-event simulations. A sizable suppression of the angular correlations between the magnetic field and the 2nd and 4th harmonic participant planes is found in very central and very peripheral collisions, while the magnitudes of these correlations peak around impact parameter b~8-10 fm for RHIC collisions. This can lead to notable impacts on a number of observables related to various magnetic field induced effects, and our finding suggests that the optimal event class for measuring them should be that corresponding to b~8-10 fm. 
John Bloczynski, Xu-Guang Huang, Xilin Zhang, and Jinfeng Liao
nucl-th hep-ph nucl-ex