$\psi(2S)$ photoproduction in high energy nuclear collisions

TL;DR

This paper investigates the coherent photoproduction of $'$ mesons in high energy nuclear collisions, analyzing the hot medium effects and yield ratios, with implications for understanding charmonium production.

Contribution

It introduces a model for charmonium photoproduction considering the competition between fireball and nuclear sizes, highlighting conditions where hot medium effects are minimal or significant.

Findings

Photoproduction yield ratio of ' to J/ ext{ in Pb-Pb collisions at LHC energy.

Hot medium effects are negligible when fireball size is smaller than nuclear size.

Potential enhancement of ' production at low transverse momentum.

Abstract

We study coherent photoproduction of $\psi'$ and the subsequent suppression in high energy nuclear collisions. The hot medium effect on charmonium photoproduction is controlled by the competition between the fireball size and nuclear size. When the former is smaller than the later, the photoproduction is only slightly affected by the hot medium. We calculate the yield ratio of $\psi'$ to $J/\psi$ in semi-central Pb-Pb collisions at LHC energy, while the high $p_T$ limit is characterized by the fireball, its value in low $p_T$ limit can still reach the significant enhancement by photoproduction.