9-15 July 2017
Victor J. Koningsberger building
Europe/Amsterdam timezone

Quarkonium production in pp and p-A collisions with ALICE at the LHC

13 Jul 2017, 09:40
20m
BBG 161 ()

BBG 161

oral presentation Small systems (pA) Parallel Small systems

Speaker

Astrid Morreale (Centre National de la Recherche Scientifique (FR))

Description

Quarkonia are mesons formed of either a charm and anti-charm quark pair ($\rm{J}/\psi$, $\psi(2S)$), or a beauty and anti-beauty quark pair ($\Upsilon$(1S), (2S) and (3S)). In high-energy hadronic collisions such as those delivered by the LHC between 2010 and 2016, quarkonium production results from the hard scattering of two gluons in a process which occurs very early in the collision followed by the hadronization of the heavy quark pair in a bound state. In pp collisions, quarkonium measurements help characterize production mechanisms and provide a reference baseline for p-A and A-A measurements. In p-A collisions these measurements quantify cold nuclear properties such as nuclear shadowing, gluon saturation, energy loss or break-up of the c\bar{c} pair in the medium. Disentangling cold nuclear effects from hot nuclear properties of the Quark-Gluon Plasma (QGP)is essential for the evaluation of the size of hot matter effects on charmonia in a QGP environment.

While charmonia are produced rather abundantly in such collisions, interpreting the measurement of their inclusive production is complicated by the presence of a sizable non-prompt contribution from the decay of b-hadrons. Bottomonia on the other hand have much smaller production cross sections but no non-prompt contribution. Moreover, their heavier mass makes them more suitable for perturbative QCD calculations.

In this presentation we will report on forward rapidity ($2.5 < y < 4$) $\rm{J}/\psi$ and $\psi(2S)$ production measured in pp collisions at center of mass energies $\sqrt{s}=5.02$ and $13$~TeV, using data collected at the LHC in 2015. Together with similar measurements performed at $\sqrt{s}=2.76$, $7$ and $8$ TeV, these results constitute a stringent test for models of charmonium production. In particular, they will be compared to NRQCD and FONLL calculations, which describe prompt and non-prompt charmonium production, respectively.

First Run-2 results on the J/$\psi$ and $\psi$(2S) production measurements in p-Pb collisions at sqrt{s_{\rm{NN}}}= 8.16 TeV, at forward and backward rapidities, will also be presented, together with new mid-rapidity J\psi results at sqrt{s_{\rm{NN}}}= 5.02 TeV. The J/$\psi$ and $\psi$(2S) nuclear modification factors will be compared to Run-1 results as well as theoretical calculations and will be interpreted in terms of cold nuclear matter effects.

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