Photoproduction of e+e− in peripheral isobar collisions

Abstract

We investigate the photoproduction of dielectrons in peripheral collisions of $_{44}^{96}\mathrm{Ru}+_{44}^{96}\mathrm{Ru}$ and $_{40}^{96}\mathrm{Zr}+_{40}^{96}\mathrm{Zr}$ at 200 GeV. With the charge and mass density distributions given by the calculation of the density functional theory, we calculate the spectra of transverse momentum, invariant mass, and azimuthal angle for dielectrons at 40--80% centrality. The ratios of these spectra in $\mathrm{Ru}+\mathrm{Ru}$ collisions over to $\mathrm{Zr}+\mathrm{Zr}$ collisions are shown to be smaller than $(44/40{)}^{4}$ (the ratio of ${Z}^{4}$ for Ru and Zr) at low transverse momentum. The deviation arises from the different mass and charge density distributions in Ru and Zr. So the photoproduction of dileptons in isobar collisions may provide a new way to probe the nuclear structure.