Speaker
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 $^{96}_{44}\mathrm{Ru}$+$^{96}_{44}\mathrm{Ru}$ and $^{96}_{40}\mathrm{Zr}$+$^{96}_{40}\mathrm{Zr}$ 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.
| Theory / experiment | Experiment |
|---|---|
| Group or collaboration name | STAR Collaboration |
