Intervenant: Soohwan Lee
Title : Suppression of the upsilon excited states measured with CMS
Abstract : Owing to their heavy mass and scarce production in heavy ion collisions, bottomonia, the bound states of bottom quark-antiquark pair, have a unique aspect of probing the quark gluon plasma (QGP).
The hierarchical suppression of the S-wave Upsilons respect to their binding energy, so called the “sequential suppression”, is thought to be a common sense and backed by numerous experimental results. However, due to lack of statistics, data for the Upsilon(3S) was inconclusive.
In this talk, we present the latest measurement focused on the suppression of the excited Upsilon states with the data taken in 2018 LHC PbPb 5.02 TeV collisions with the CMS detector. The results are compared with various models which could provide a stringent test to our understanding of dynamics of bottomonia in the heavy ion collisions.
Intervenant: Peter Vander Griend
Title : Bottomonium Observables in Heavy-Ion Collisions Using Open Quantum Systems and Effective Field Theories
Abstract : Bottomonium states are among the best available probes of the medium formed in heavy-ion collisions. The large mass of the bottom quark and short bound state formation time make bottomonia ideal probes of the medium generated in such collisions. A reduced yield of bottomonium states in heavy-ion collisions relative to proton-proton collisions, which is called heavy quarkonium suppression, has long been theorized to signal the formation of a deconfined quark-gluon plasma (QGP). The widely separated hierarchy of scales inherent to in-medium bottomonia together with the out-of-equilibrium nature of its evolution in the QGP have enabled recent advances in theoretical descriptions using effective field theory (EFT) methods and the formalism of open quantum systems (OQS). In this talk, I will introduce the EFT potential nonrelativistic QCD and the OQS formalism and, using these two tools, will present the derivation of a Lindblad equation governing the in-medium evolution of bottomonia. I will close with a comparison of state-of-the-art OQS+pNRQCD predictions for the nuclear modification factor and elliptic flow with experimental data.