Production of inclusive $\Upsilon$(1S) and $\Upsilon$(2S) in p-Pb collisions at $\mathbf{\sqrt{s_{{\rm NN}}} = 5.02}$ TeV

TL;DR

This paper measures the production of $$psilon(1S) and (2S) mesons in proton-lead collisions at 5.02 TeV, revealing rapidity-dependent suppression effects and comparing results to theoretical models.

Contribution

It provides the first detailed measurement of $$psilon states in p-Pb collisions at this energy, including nuclear modification factors and rapidity ratios.

Findings

Suppression of $$psilon(1S) at forward rapidity

No suppression observed at backward rapidity

Results align with models including nuclear shadowing or energy loss

Abstract

We report on the production of inclusive $\Upsilon$(1S) and $\Upsilon$(2S) in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV at the LHC. The measurement is performed with the ALICE detector at backward ($-4.46< y_{{\rm cms}}<-2.96$) and forward ($2.03< y_{{\rm cms}}<3.53$) rapidity down to zero transverse momentum. The production cross sections of the $\Upsilon$(1S) and $\Upsilon$(2S) are presented, as well as the nuclear modification factor and the ratio of the forward to backward yields of $\Upsilon$(1S). A suppression of the inclusive $\Upsilon$(1S) yield in p-Pb collisions with respect to the yield from pp collisions scaled by the number of binary nucleon-nucleon collisions is observed at forward rapidity but not at backward rapidity. The results are compared to theoretical model calculations including nuclear shadowing or partonic energy loss effects.