Ground and excited state charmonium production inp+pcollisions ats=200  GeV

Abstract

We report on charmonium measurements [J/ψ (1S), ψ ′ (2S), and χc (1P)] in p+p collisions at √ s = 200 GeV. We find that the fraction of J/ψ coming from the feed-down decay of ψ ′ and χc in the midrapidity region (|y| < 0.35) is 9.6 ± 2.4% and 32 ± 9%, respectively. We also present the pT and rapidity dependencies of the J/ψ yield measured via dielectron decay at midrapidity (|y| < 0.35) and via dimuon decay at forward rapidity (1.2 < |y| < 2.2). The statistical precision greatly exceeds that reported in our previous publication [Phys. Rev. Lett. 98, 232002 (2007)]. The new results are compared with other experiments and discussed in the context of current charmonium production models.

Measurement of the relative yields of ψ(2S) to ψ(1S) mesons produced at forward and backward rapidity in Adare1, Aidala2, Ajitanand3 et al. 2017Phys. Rev. CSelf Cite

“…The ratios reported here are somewhat higher than the model for p T > 2 GeV/c, but the data's limited statistical precision and significant theoretical error bands preclude any firm conclusions. Comparison of world data on the ratio of ψ(2S)/ψ(1S) mesons in dilepton decays [21,29,[36][37][38][39][40][41][42].…”

“…We see that at forward rapidity, the double ratio is consistent with unity in all three collision systems, indicating that any possible nuclear effects on the two charmonium states are comparable. Because these states are not fully formed until after they exit the nucleus, the fact that any nuclear effects have an equal magnitude Comparison of world data on the ratio of ψ(2S)/ψ(1S) mesons as a function of pT [29,40,[43][44][45], along with a calculation from a color evaporation model (CEM) at √ s=200 GeV [25].…”

“…Previous PHENIX measurements were not able to resolve the smaller ψ(2S) peak in the dimuon mass spectrum near the larger, broad ψ(1S) peak (cf. [28,29]). However, the introduction of the four silicon tracking layers of the FVTX in 2012 now allows a precise measurement of the pair opening angle to be made before the muons undergo multiple scattering in the absorber.…”

Measurement of J/ψ production in p + p collisions at s=500 GeV at STAR experiment

“…It is about 3.5% at p T ≈ 6.8 GeV/c with a total systematic uncertainty of about 18%. Compared with other measurements at different colliding energies for p + p or p + A systems, the current measurement follows the trend of p T dependence and shows no colliding energy dependence [5,6,7].…”

Heavy quark state production in Pb-Pb collisions at s pp = 5.02 $$ \sqrt{s_{pp}}=5.02 $$ TeV

“…while the PHENIX experimental result for the ratio [19] 0.59. Therefore, as in our earlier work the hybrid model is consistent with experiment, while the standard model ratio is too small.…”