Observation of excess J/$\psi$ yield at very low transverse momenta in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV and U+U collisions at $\sqrt{s_{\mathrm{NN}}}=$ 193 GeV

Abstract

We report on the first measurements of J/$\psi$ production at very low transverse momentum ($p_T<$ 0.2 GeV/c) in hadronic Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 200 GeV and U+U collisions at $\sqrt{s_{\mathrm{NN}}}=$ 193 GeV. Remarkably, the inferred nuclear modification factor of J/$\psi$ at mid-rapidity in Au+Au (U+U) collisions reaches about 24 (52) for $p_T<$ 0.05 GeV/c in the 60-80$\%$ collision centrality class. This noteworthy enhancement cannot be explained by hadronic production accompanied by cold and hot medium effects. In addition, the $dN/dt$ distribution of J/$\psi$ for the very low $p_T$ range is presented for the first time. The distribution is consistent with that expected from the Au nucleus and shows a hint of interference. Comparison of the measurements to theoretical calculations of coherent production shows that the excess yield can be described reasonably well and reveals a partial disruption of coherent production in semi-central collisions, perhaps due to the violent hadronic interactions. Incorporating theoretical calculations, the results strongly suggest that the dramatic enhancement of J/$\psi$ yield observed at extremely low $p_T$ originates from coherent photon-nucleus interactions. In particular, coherently produced J/$\psi$'s in violent hadronic collisions may provide a novel probe of the quark-gluon-plasma.

References in corpus (34)

• The order of the quantum chromodynamics transition predicted by the standard model of particle physics
• Glauber Modeling in High Energy Nuclear Collisions
• Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR
• EPS09 - a New Generation of NLO and LO Nuclear Parton Distribution Functions
• The STAR Time Projection Chamber: A Unique Tool for Studying High Multiplicity Events at RHIC
• Physics of Ultra-Peripheral Nuclear Collisions
• J/psi Production vs Centrality, Transverse Momentum, and Rapidity in Au+Au Collisions at sqrt(s_NN) = 200 GeV
• Exclusive Vector Meson Production in Relativistic Heavy Ion Collisions
• STARlight: A Monte Carlo simulation program for ultra-peripheral collisions of relativistic ions
• J/$\psi$ suppression at forward rapidity in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Suppression of non-prompt J/psi, prompt J/psi, and Y(1S) in PbPb collisions at sqrt(sNN) = 2.76 TeV
• Charmonium and $e^{+}{e}^{-}$ pair photoproduction at mid-rapidity in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$=2.76 TeV
• Coherent J/$\psi$ photoproduction in ultra-peripheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• J/psi Transverse Momentum Distribution in High Energy Nuclear Collisions
• J/psi Production in Quark-Gluon Plasma
• Charmonium in Medium: From Correlators to Experiment
• Measurement of the centrality dependence of J/ψ yields and observation of Z production in lead-lead collisions with the ATLAS detector at the LHC
• Interference in Exclusive Vector Meson Production in Heavy Ion Collisions
• Photoproduction of J/psi and of high mass e+e- in ultra-peripheral Au+Au collisions at sqrt(s_NN) = 200 GeV
• Coherent J/psi photoproduction in ultra-peripheral PbPb collisions at sqrt(s[NN]) = 2.76 TeV with the CMS experiment
• Diffractive Heavy Quarkonium Photo- and Electroproduction in QCD
• Measurement of an excess in the yield of J/$\psi$ at very low $p_{\mathrm{T}}$ in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV
• Low-$p_T$ $e^{+}{e}^{-}$ pair production in Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U$+$U collisions at $\sqrt{s_{NN}}$ = 193 GeV at STAR
• J/$\psi$ production at high transverse momenta in p+p and Au+Au collisions at sqrt(s_{NN}) = 200 GeV
• Measurements of Dielectron Production in Au$+$Au Collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV from the STAR Experiment
• Exclusive J/ψ production in ultraperipheral collisions at the LHC: constrains on the gluon distributions in the proton and nuclei
• Cold nuclear matter effects on J/psi production: intrinsic and extrinsic transverse momentum effects
• $J/\psi$ production at low $p_T$ in Au+Au and Cu+Cu collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV at STAR
• The STAR Vertex Position Detector
• Coherent J/$\psi$ photoproduction in hadronic heavy-ion collisions
• Coherent rho and J/psi photoproduction in ultraperipheral processes with electromagnetic dissociation of heavy ions at RHIC and LHC
• Energy dependence of $J/\psi$ production in Au+Au collisions at $\sqrt{s_{NN}}=$ 39, 62.4 and 200 GeV
• Observation of Two-source Interference in the Photoproduction Reaction $AuAu\to AuAu{\rho }^0$
• Systematic study of the experimental measurements on $J/\psi$ cross section and kinematic distribution in $p+p$ collisions at different energies

Cited by in corpus (15)

• Photonuclear and Two-photon Interactions at High-Energy Nuclear Colliders
• First measurement of the $|\text{t}|$-dependence of coherent $J/\psi$ photonuclear production
• The Present and Future of QCD
• An experimental review of open heavy flavor and quarkonium production at RHIC
• Mapping the Electromagnetic Fields of Heavy-Ion Collisions with the Breit-Wheeler Process
• Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV
• The $\cos 2\varphi$ azimuthal asymmetry in ${\rho }^0$ meson production in ultraperipheral heavy ion collisions
• Report on Progress in Physics: Observation of the Breit-Wheeler Process and Vacuum Birefringence in Heavy-Ion Collisions
• $J/\psi$ photo-production in Pb-Pb peripheral collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5 TeV
• Quarkonium propagation in the quark gluon plasma
• Prospects for quarkonium studies at the high-luminosity LHC
• Coulomb nuclear interference effect in dipion production in ultraperipheral heavy ion collisions
• Challenges to the Good-Walker paradigm in coherent and incoherent photoproduction
• Photoproduction of low-$p_{\mathrm{T}}$ J/$\psi$ from peripheral to central Pb$-$Pb collisions at 5.02 TeV
• Measurement of inclusive $J/\psi$ production in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=54.4$ GeV at STAR