1209.0331 (J. P. Lansberg)

Upsilon production in pp and pA collisions: from RHIC to the LHC    [PDF]

J. P. Lansberg

I first discuss Upsilon production in pp collisions at RHIC, Tevatron and LHC energies, in particular the behaviour of the differential cross section in rapidity and the impact of QCD corrections on the P_T differential cross section. I also emphasise the very good agreement between the parameter-free predictions of the Colour-Singlet Model (CSM) and the first LHC data, especially in the region of low transverse momenta, which is the most relevant one for heavy-ion studies. I also show that the CSM gives predictions for Upsilon cross-section ratios in agreement with the most recent LHC data from CMS and LHCb. I then briefly discuss the nuclear-matter effects on Upsilon production at RHIC and the LHC in proton-nucleus collisions and, by extension, in nucleus-nucleus collisions. I argue that (i) the Upsilon break-up probability can be neglected in a first approximation, both at RHIC and the LHC, (ii) the gluon shadowing --although non-negligible-- is not strong enough to describe the forward RHIC data, (iii) the backward RHIC data hints at a gluon EMC effect, possibly stronger than the quark one. Following these discussions, outlooks for the LHC pPb run are presented.

View original: http://arxiv.org/abs/1209.0331