25ème Congrès Général de la SFP 2019

Measurement of an excess in the yield of J/ψ at very low pT in Pb-Pb collisions at sNN=5.02 TeV with ALICE

Non programmé

20m

Auditorium 450 (Cité des Congrès)

Poster Séance Poster

Orateur

Ophélie Bugnon (Subatech)

Description

In 2015, the ALICE collaboration reported the first excess in the yield of $J/\psi$ at very low transverse momentum ($p_T<0.3GeV/c$) in the forward rapidity region ($2.5<y<4$) in peripheral Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the CERN LHC. [1] The coherent photo-production is proposed as the potential underlying physics mechanism. This mechanism is the main responsible for low-$p_T$ $J/\psi$ production in ultra-peripheral collisions. However, the observation of a large effect also in more central collisions that are dominated by the hadronic interactions was quite surprising. If the photo-production is confirmed as the origin of the excess, this will open up fundamental questions on the nature of the coherence in collisions where the nuclei break up. Furthermore, the $J/\psi$ from the coherent photo-production might become an additional probe of the Quark and Gluon Plasma. This poster presents the analysis strategy for Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$ TeV for which the data sample is expected to be about thirty times larger than at $\sqrt{s_{NN}}=2.76$ TeV.

References
[1] ALICE Collaboration, J. Adam et al., “Measurement of an excess in the yield of $J/\psi$ at very low $p_T$ in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV", Phys.Rev.Lett.116(2016) 222301, arXiv:1509.08802 [nucl-ex].