Measurements of the suppression of the yield per nucleon of J/Psi and Psi production for 800 GeV/c protons incident on heavy relative to light nuclear targets have been made with very broad coverage in xF and pT. The observed suppression is smallest at xF values of 0.25 and below and increases at larger values of xF. It is also strongest at small pT. Substantial differences between the Psi and J/Psi are observed for the first time in p-A collisions. The suppression for the Psi is stronger than that for the J/Psi for xF near zero, but becomes comparable to that for the J/Psi for xF > 0.6.
The NA60 experiment studies dimuon production in In-In and p-A collisions at the CERN SPS. We report recent results on jpsi production, measured through its muon pair decay. As a function of centrality, we show that in In-In the jpsi yield is suppressed beyond expectations from nuclear absorption. We present also for the first time results on jpsi production in p-A collisions at 158 GeV, the same energy of the nucleus-nucleus data. For both p-A and In-In we show preliminary results on psip suppression. Finally, we have studied the kinematical distributions of the jpsi produced in In-In collisions. We present results on transverse momentum and rapidity, as well as on the angular distribution of the jpsi decay products.
The NA60 experiment has studied J/$psi$ production in Indium-Indium collisions at 158 A$cdot$GeV. In this paper we present an updated set of results obtained with the complete set of available statistics and an improved alignment of the vertex tracker. The centrality dependence of the J/$psi$ production, obtained with an analysis technique based only on the J/$psi$ sample, indicates that a suppression beyond that induced by nuclear absorption is present in In-In collisions, setting in at $sim$80 participant nucleons. A first study of the systematic errors related with this measurement is discussed. We also present preliminary results on the J/$psi$ azimuthal distributions.
The preliminary results of J/psi spectra at high transverse momentum (5<p_T<14 GeV/c) in p+p and Cu+Cu collisions at s_NN = 200 GeV are reported. The nuclear modification factor is measured to be 0.9+/-0.2 at p_T>5 GeV/c. The correlations between J/psi and charged hadrons are also studied in p+p collisions to understand the J/psi production mechanism at high p_T.
In this paper, results on the J/psi cross section and polarization measured via the dielectron decay channel at mid-rapidity in p+p collisions at 200 and 500 GeV in the STAR experiment are discussed. Also, first measurements of the J/psi production as a function of the charged-particle multiplicity density and of psi(2S) to J/psi ratio at 500 GeV are reported.
An amplitude analysis of flavour-untagged $B_s^0 to J/psi p bar{p}$ decays is performed using a sample of $797pm31$ decays reconstructed with the LHCb detector. The data, collected in proton-proton collisions between 2011 and 2018, correspond to an integrated luminosity of 9 $text{fb}^{-1}$. Evidence for a new structure in the $J/psi p$ and $J/psi bar{p}$ systems with a mass of $4337 ^{+7}_{-4} ^{+2}_{-2}~text{MeV}$ and a width of $29 ^{+26}_{-12} ^{+14}_{-14}~text{MeV}$ is found, where the first uncertainty is statistical and the second systematic, with a significance in the range of 3.1 to 3.7 $sigma$, depending on the assigned $J^P$ hypothesis.