The 9th Asian Triangle Heavy-Ion Conference (ATHIC 2023)

Initial electromagnetic field dependence of photon-induced production in isobaric collisions at STAR

24 Apr 2023, 14:15

25m

Multi-Purpose Studio, 2nd Floor (JMS Aster Plaza)

Oral Electromagnetic probes Parallel Session C

Speaker

Kaifeng Shen

Description

The Lorentz-boosted electromagnetic field, arising from a colliding nucleus, can be treated as a flux of quasi-real photons. Consequent photonuclear ($\propto$ $Z^2$) and photon-photon ($\propto$ $Z^4$) processes could reasonably explain the observed enhancements of $J/\psi$ and $e^{+}{e}^{-}$ pair production at very low transverse momenta ($p_T$) in peripheral heavy-ion collisions. The STAR experiment collected datasets of ${}_{44}^{96}\mathrm{Ru}$+${}_{44}^{96}\mathrm{Ru}$ and ${}_{40}^{96}\mathrm{Zr}$+${}_{40}^{96}\mathrm{Zr}$ collisions at 200 GeV in 2018, which provide a unique opportunity to study photon-induced processes.

In this presentation, we will compare measurements of $J/\psi$ and $e^{+}{e}^{-}$ pair production at very low $p_T$ in isobaric and Au+Au collisions to study their electromagnetic field dependence. The angular modulation of dielectron pairs will also be presented. Physics implications of these results will be discussed together with model comparisons.

Presentation materials

ATHIC2023_202304_v6.pdf