Related papers: QCD calculation of J/psi+gamma mass distributions
We study the process $\bar p p \rightarrow J/\psi + \gamma +X$ at the Tevatron energy ($\sqrt{s} = 1.8$~TeV). The perturbative QCD contributions to this process from the gluon-fusion and the fragmentation mechanisms are computed. For the…
The associated production of J/psi + gamma at the LHC is studied within the NRQCD framework. The signal we focus on is the production of a J/psi and an isolated photon produced back-to-back, with their transverse momenta balanced. It is…
We investigate the reaction gamma+p -> V+p, with V denoting a Phi or a J/Psi meson, within the scope of perturbative QCD, treating the proton as a quark-diquark system. Our predictions extrapolate the existing forward differential…
We have used a study of the process e+e- --> mu+ mu- gamma at a center-of-mass energy near the Y(4S) resonance for a mu+ mu- invariant mass range near the J/psi mass to extract the cross section sigma(e+e- --> J/psi gamma --> mu+ mu-…
A reaction model for $\gamma + p \to J/\psi + p$ photoproduction, which exposes the $c \bar c$ content of the photon in making the transition $\gamma\to c\bar c + \mathbb P \to J/\psi$ and couples the intermediate $c \bar c$ system to the…
We compute the O(alpha_s^2) correction to the decay rate eta_c --> gamma gamma and discuss its implications for precision quarkonium physics. We study the suitability of the ratio Gamma(J/psi --> e+e-)/Gamma(eta_c --> gamma gamma), in which…
In this work we present the $J/\psi$ measurement in p+p collisions within the STAR collaboration Quarkonium program. This measurements aim to be the baseline measurement of a more comprehensive systematic study of quarkonium states…
In this paper, we present an improved calculation for the decay rate of the rare $Z$-boson decay into $J/\psi + J/\psi$. This decay is dominated by the photon fragmentation mechanism, i.e., the transition $Z\to J/\psi + \gamma^{*}$ followed…
We calculate the cross section for the $\gamma \gamma \to J/\psi J/\psi$ process. Two mechanisms are considered: box (two-loop) diagrams of the order of $O(\alpha_{em}^2 \alpha_s^2)$ and two-gluon exchange of the order of $O(\alpha_{em}^2…
It has been suggested that the suppression of $J/\psi$ production in heavy nuclei is a signature of the formation of quark-gluon plasma. We here show that this phenomenon can be understood in terms of conventional physics, {\it i.e.} {\it…
We investigate the process $e^{+}e^{-} \rightarrow K\bar{K}J/\psi$ at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb$^{-1}$ of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the…
Inelastic photoproduction of $J/\psi$ particles at high energies is one of the processes to determine the gluon distribution in the nucleon. We have calculated the QCD radiative corrections to the color-singlet model of this reaction. They…
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…
We calculate the invariant-mass distribution for the cc-bar pair produced in the inclusive Upsilon(1S) decay based on the color-singlet mechanism of the nonrelativistic quantum chromodynamics factorization approach at leading order in the…
Recent measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. We suggest that a significant part of the discrepancy can be explained by…
Studying the production of J/$\psi$ (bound state of charm and anti-charm quark) in proton-proton collisions gives an opportunity to test quantum chromodynamics (QCD) calculations, as the production of J/$\psi$ involves both perturbative and…
We investigate two exclusive processes, e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi, at the center-of-momentum energy sqrt{s}=10.58 GeV within the framework of the nonrelativistic QCD factorization approach. A class of relativistic…
Combining the hydrodynamic equations for the QGP evolution and the transport equation for the primordially produced $J/\psi$ in the QGP, we investigate the $J/\psi$ transverse momentum distribution as well as its suppression in the…
The transverse momentum (pt) dependence of J/psi production in heavy ion collisions is investigated in a transport model with both initial production and continuous regeneration of charmonia. The competition between the two production…
QCD phase diagram is obtained by analysing centrality dependence of $J/\psi$ suppression in $\snn$=17.3 Pb+Pb and $\snn$=200 GeV Au+Au collisions. $J/\psi$'s produced in initial interactions are assumed to dissolve if local temperature…