Upsilon suppression in PbPb collisions at the LHC

TL;DR

This paper explains the observed suppression of Upsilon states in PbPb collisions at the LHC as a combined effect of screening, dissociation, damping, and feed-down reduction, indicating the formation of quark-gluon plasma.

Contribution

It provides a comprehensive explanation for Upsilon suppression by integrating multiple physical mechanisms, highlighting their relative roles for different states.

Findings

Upsilon suppression indicates quark-gluon plasma formation.

Different suppression mechanisms dominate for ground and excited states.

The combined effects match experimental observations.

Abstract

We suggest that the combined effect of screening, gluon-induced dissociation, collisional damping, and reduced feed-down explains most of the sequential suppression of Upsilon(nS) states that has been observed in PbPb relative to pp collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit indirect, indication for the presence of a QGP. The Upsilon(1S) ground state suppression is essentially due to reduced feed-down, collisional damping and gluodissociation, whereas screening prevails for the suppression of the excited states.