Bottomonium suppression and regeneration in p + Pb collisions at LHC energies

We investigate bottomonium suppression and regeneration in minimum-bias proton-lead (p+Pb) collisions at center-of-mass energies of 5.02 and 8.16 TeV, as observed at the LHC. We account for cold nuclear matter (CNM) effects, including nuclear modifications to parton distribution functions (using EPPS21 nPDFs), coherent energy loss, and momentum broadening. Hot nuclear matter (HNM) effects are modeled through the evolution of a quark-gluon plasma (QGP), simulated with 3+1D viscous anisotropic hydrodynamics. Bottomonium dynamics within the QGP are evaluated using a semiclassical approach with two distinct methods: (1) a perturbative treatment (TAMU-P) incorporating quasi-free inelastic scattering and gluo-dissociation, and (2) a non-perturbative (TAMU-NP) approach employing in-medium T-matrix calculations with a lattice QCD-constrained potential [2]. These methods enable us to assess both suppression and regeneration processes. Notably, the more recent non-perturbative TAMU-NP approach reveals significant regeneration effects, which are crucial for accurately interpreting the observed modification patterns. We calculate the total nuclear modification factor RpA taking CNM effects first with only the primordial suppression, and then all combined with regeneration for Υ(nS) states as a function of rapidity and transverse momentum. Our predictions are compared with experimental data from ALICE, ATLAS, CMS, and LHCb, showing good agreement and suggesting the presence of a transient QGP in small collision systems with strong non-perturbative effects into play in the qarkonium kinetics. We also compare these semi-classical calculations with the quantum mechanical approach based on open quantum system framework with potential non-relativistic quantum chromodynamics [1]. Additionally, we provide predictions for χb states offering a 2 basis for future experimental validation.

[1] M. Strickland, S. Thapa, and R. Vogt. Bottomonium suppression in 5.02 and 8.16 TeV p-Pb collisions. Phys. Rev. D, 109(9):096016, 2024.

[2] S. Thapa, B. Wu, R. Vogt, J. Boyd, R. Rapp, and M. Strickland. Semi-classical treatment of bottomonium suppression in p-Pb collisions. In Preparation.