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T.Barnes
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This paper gives results for the spectrum, all allowed E1 radiative partial widths (and some important M1 widths) and all open-charm strong decay amplitudes of all 40 c-cbar states expected up to the mass of the 4S multiplet, just above 4.4 GeV. The spectrum and radiative widths are evaluated using two models, the relativized Godfrey-Isgur model and a nonrelativistic potential model. The electromagnetic transitions are evaluated using Coulomb plus linear plus smeared hyperfine wavefunctions, both in a nonrelativistic potential model and in the Godfrey-Isgur model. The open-flavor strong decay amplitudes are determined assuming harmonic oscillator wavefunctions and the 3P0 decay model. This work is intended to motivate future experimental studies of higher-mass charmonia, and may be useful for the analysis of high-statistics data sets to be accumulated by the BES, CLEO and GSI facilities.
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A colorless c-cbar dipole emerging from a heavy ion collision and developing the charmonium wave function can be broken-up by final state interactions (FSI) propagating through the hot medium created in the collision. We single out two mechanisms of charmonium attenuation: (i) Debye color screening, called melting; and (ii) color-exchange interaction with the medium, called absorption. The former problem has been treated so far only for charmonia at rest embedded in the medium, while in practice their transverse momenta at the LHC are quite high, <p_T^2>=7-10 GeV^2. We demonstrate that a c-cbar dipole may have a large survival probability even at infinitely high temperature. We develop a procedure of Lorentz boosting of the Schroedinger equation to a moving reference frame and perform the first realistic calculations of the charmonium survival probability employing the path-integral technique, incorporating both melting and absorption. These effects are found to have comparable magnitudes. We also calculated the FSI suppression factor for the radial excitation psi(2S) and found it to be stronger than for J/psi, except large p_T, where psi(2S) is relatively enhanced. The azimuthal asymmetry parameter v_2 is also calculated.
We investigate the in-medium masses of open charm mesons ($D$($D^0$, $D^+$), $bar{D}$($bar{D^0}$, $D^-$), $D_s$(${D_{s}}^+$, ${D_{s}}^-$)) and charmonium states ($J/psi$, $psi(3686)$, $psi(3770)$, $chi_{c0}$, $chi_{c2}$) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective model. In the presence of the magnetic field, the number density and scalar density of charged baryons have contributions from Landau energy levels. The mass modifications of open charm mesons arise due to their interactions with nucleons, hyperons, and the scalar fields (the non-strange field $sigma$, strange field $zeta$ and isovector field $delta$) in the presence of the magnetic field. The mass modifications of the charmonium states arise from the variation of dilaton field ($chi$) in the magnetized medium, which simulates the gluon condensates of QCD. The in-medium mass of open charm mesons and charmonia are observed to decrease with an increase in baryon density, whereas the charged $D^+$, $D^-$, ${D_{s}}^+$ and ${D_{s}}^-$ mesons have additional positive mass shifts due to Landau quantization in the presence of the magnetic field. The effects of strangeness fraction are found to be more dominant for the $bar{D}$ mesons as compared to the $D$ mesons. The mass shifts of charmonia are observed to be larger in hyperonic medium compared to the nuclear medium.
Quarkonia states are expected to provide essential information on the properties of the high-density strongly-interacting system formed in the early stages of high-energy heavy-ion collisions. ALICE is the LHC experiment dedicated to the study of nucleus-nucleus collisions and can study charmonia at forward rapidity (2.5 < y < 4) via the mu+ mu- decay channel and at mid rapidity (|y| < 0.9) via the e+ e- decay channel. In both cases charmonia are measured down to zero transverse momentum. The inclusive J/psi production as a function of transverse momentum and rapidity in pp collisions at sqrt{s} = 2.76 and 7 TeV are presented. For pp collisions at sqrt{s} = 7 TeV, the inclusive J/psi production as a function of the charged particle multiplicity, the inclusive J/psi polarization at forward rapidity and the J/psi prompt to non-prompt fraction are discussed. Finally, the analysis of the inclusive J/psi production in the Pb-Pb data collected fall 2011 at a center of mass energy of sqrt{s_{NN}} = 2.76 TeV is presented. Results on the nuclear modification factor are then shown as a function of centrality, transverse momentum and rapidity and compared to model predictions. First results on inclusive J/psi elliptic flow are given.
We compute the inclusive jet spectrum in the presence of a dense QCD medium by going beyond the single parton energy loss approximation. We show that higher-order corrections are important yielding large logarithmic contributions that must be resummed to all orders. This reflects the fact that jet quenching is sensitive to fluctuations of the jet substructure.
We calculate the non-normalized moments of the particle multiplicity within the framework of the hadron resonance gas (HRG) model. At finite chemical potential $mu$, a non-monotonic behavior is observed in the thermal evolution of third order moment (skewness $S$) and the higher order ones as well. Among others, this observation likely reflects dynamical fluctuations and strong correlations. The signatures of non-monotonicity in the normalized fourth order moment (kurtosis $kappa$) and its products get very clear. Based on these findings, we introduce a novel condition characterizing the universal freeze-out curve. The chemical freeze-out parameters $T$ and $mu$ are described by vanishing $kappa, sigma^2$ or equivalently $m_4=3,chi^2$, where $sigma$, $chi$ and $m_4$ are the standard deviation, susceptibility and fourth order moment, respectively. The fact that the HRG model is not able to release information about criticality related to the confinement and chiral dynamics should not veil the observations related to the chemical freeze-out. Recent lattice QCD studies strongly advocate the main conclusion of the present paper.
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