The effect of initial nuclear deformation on dielectron photoproduction in hadronic heavy-ion collisions

Abstract

Significant excesses of $e^{+}{e}^{-}$ pair production at very low transverse momentum ($p_T<$ 0.15 GeV/c) were observed by the STAR collaboration in hadronic heavy-ion collisions. Such enhancement is assumed to be a sign of photon-photon production in heavy-ion collisions with hadronic overlap, based on comparisons with model calculations for spherical Au + Au collisions. However, there is a lack of calculations for $e^{+}{e}^{-}$ pair production from coherent photon-photon interactions in hadronic U + U collisions, due to the deformity of Uranium nuclei. In this article, we present calculations for $e^{+}{e}^{-}$ pair photoproduction at $\sqrt{s_{NN}}$ = 193 GeV in both spherical and deformed U + U collisions within STAR detector acceptance using the equivalent photon approximation (EPA). We conduct event-by-event analysis to investigate the effects of initial nuclear deformation on pair production. Our numerical results show good agreement with experimental data for the 40%--60% and 60%--80% centrality classes in U + U collisions, and the differences between spherical and deformed configurations are approximately 3\%. We also calculate the yields of the photoproduced $e^{+}{e}^{-}$ pair in hadronic deformed Ru + Ru and Zr + Zr collisions at $\sqrt{s_{NN}}$ = 200 GeV. The results reveal that the ratios of the yields of Ru to Zr exhibit very small differences ($<$ 1%) between spherical and deformed cases.

8 pages, 5 figures, 4 tables

References in corpus (7)

• Glauber Modeling in High Energy Nuclear Collisions
• The Physics of Ultraperipheral Collisions at the LHC
• Testing the Chiral Magnetic Effect with Central U+U collisions
• Predictions of elliptic flow and nuclear modification factor from 200 GeV U + U collisions at RHIC
• Reaction plane alignment with linearly polarized photon in heavy-ion collisions
• Azimuthal asymmetries of muon pair production in ultraperipheral heavy ion collisions
• Photoproduction of $e^{+}{e}^{-}$ in peripheral isobar collisions

Cited by in corpus (1)

• Nuclear deformation effects in photoproduction of $\rho$ mesons in ultraperipheral isobaric collisions