Measurement Of J Psi And Psi 2s At Forward And Backward Rapidity In P P P Al P Au And 3he Au Collisions At Snn

Measurement of J/[psi] and [psi](2S) at Forward and Backward Rapidity in P+p, P+Al, P+Au, and 3He+Au Collisions at √snn

Suppression of the J/psi nuclear modification factor has been seen as a trademark signature of final state effects in large collision systems for decades. In small systems, the nuclear modification was attributed to cold nuclear matter effects until the observation of strong differential suppression of the psi(2S) state in p/d+A collisions suggested the presence of final state effects. Results of J/psi and psi(2S) measurements in the dimuon decay channel are presented here for a collection of different small systems at the same collision energy. These small systems include: p+p, p+Al, p+Au and 3He+Au at collision energy square root s_NN = 200 GeV. The results are predominantly shown in the form of the nuclear modification factor, R_AB, the ratio of the J/psi or psi(2S) invariant yield per nucleon-nucleon collision in collisions of projectile A on target B to that in p+p collisions. Measurements of the J/psi and psi(2S) nuclear modification factor are then compared with shadowing and transport model predictions, as well as to complementary measurements at LHC energies.

Measurement of Prompt Psi(2S) to J/psi Yield Ratios in PbPb and Pp Collisions at Sqrt(s[NN]

The ratio between the prompt psi(2S) and J/psi yields, reconstructed via their decays into muon pairs, is measured in PbPb and pp collisions at sqrt(s[NN]) = 2.76 TeV. The analysis is based on PbPb and pp data samples collected by CMS at the LHC, corresponding to integrated luminosities of 150 inverse microbarns and 5.4 inverse picobarns, respectively. The double ratio of measured yields, (N[psi(2S)]/N[J/psi])[PbPb] / (N[psi(2S)]/ N[J/psi])[pp], is computed in three PbPb collision centrality bins and two kinematic ranges: one at midrapidity, abs(y)

J/psi Suppression at Forward Rapidity in Au+Au Collisions at Sqrt(s_NN)