Speaker
Description
Bottomonium bound states serve as invaluable probes of the quark-gluon plasma (QGP) in relativistic heavy-ion collisions, owing to their negligible thermal production and non-relativistic nature that allows a theoretical description via potential non-relativistic QCD (pNRQCD). However, recent lattice QCD calculations of the in-medium bottomonium potential have yielded qualitatively distinct results---differing in the relative strengths of color screening and singlet-to-octet transitions---which motivates a data-driven approach to constraining the potential from experimental measurements.
We first perform a Bayesian analysis to extract the in-medium bottomonium potential by numerically solving the time-dependent Schroeodinger equation and comparing the resulting nuclear modification factors ($R_{AA}$) of $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ with LHC data. The Schroeodinger framework exhibits two competing scenarios by displaying the posterior distribution with a bimodal structure, which may be insufficient for a definitive determination of the potential.
The Schoeodinger framework does not account for the octet-to-singlet regeneration, which has been recently suggested important in bottomonium production. We go beyond the pure-state description and investigate bottomonium production within the density-matrix description. The $b\bar{b}$ density matrix, comprising both color-singlet and color-octet blocks, evolves according to a Lindblad master equation where the collapse operators are directly matched to the imaginary potential from lattice QCD, thereby naturally incorporating quantum regeneration of singlet states from octet configurations. It is shown that regeneration is more important when a potential with a larger imaginary part, i.e., stronger transitions between singlet and octet states, is used. This indicates that the Bayesian analysis based on the Lindblad framework should be taken into consideration.
References:
1. Shuhan Zheng, B. Chen, X. Du and S. Shi. Phys. Rev. C b8n3-yrq1.
2. Shuhan Zheng and S. Shi. ArXiv: 2607.06191.
