Inelastic heavy quarkonium photoproduction in p-p and Pb-Pb collisions at LHC energies

2022/03/23 by Ma, Zhi-Lei, Lu, Zhun, Liu, Hao +1
#FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph)

paper · doi:10.48550/arxiv.2203.12153

Abstract

We study the inelastic charmonium (J/ψ, ψ(2S)) and bottomonium (Υ(nS)) photoproduction and fragmentation processes in p-p and Pb-Pb collisions at LHC energies, where the ultra-incoherent photon emission is included. In the framework of the NRQCD factorization approach, an exact treatment is developed which recovers Weizsäcker-Williams approximation (WWA) near the region Q²∼0, where the methods of Martin-Ryskin and BCCKL are used to avoid double counting. We calculate the Q², y, z, √(s), p_T dependent and the total cross sections. It turns out that the inelastic photoproduction and fragmentation processes provide valuable contributions to the heavy quarkonium production, especially in the large p_T regions. While the relative contribution of ultra-incoherent photon channel is very important, which rapidly increases along with the growing quarkonium mass, and begins to dominate the photoproduction processes at large p_T ranges. Moreover, we obtain the complete validity scopes of WWA in inelastic heavy quarkonium photoproduction in heavy-ion collisions. WWA has a much higher accuracy at high energies and in Pb-Pb collisions. The existing photon spectra are generally derived beyond the applicable scopes of WWA, and the double counting exists when the different channels are considered simultaneously.

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