Related papers: Dynamics in near-threshold $J/\psi$ photoproductio…
We report on an attempt to describe hard exclusive photoproduction of $J/\Psi$ mesons, i.e. the reaction $\gamma p \to J/\Psi p$, by means of a modified version of the hard-scattering approach, in which the proton is treated as a…
New threshold measurements for $\gamma~p\to p~J/\psi \to p~(\mu^+\mu^-)$ by 007 and $\gamma^\ast~p\to p~J/\psi \to p~(e^+e^-)$ by CLAS12 allow us to extend the previous phenomenological determination of the J/\ensuremath{\psi}-proton…
According to quantum chromodynamics, at sufficiently high energy, the structure of hadrons reveals a dynamic equilibrium between gluon splitting and gluon recombination -- a phenomenon known as saturation. The process of diffractive…
We study diffractive photoproduction of $J/\psi$ by taking the charm quark as a heavy quark. A description of nonperturbative effect related to $J/\psi$ can be made by using NRQCD. In the forward region of the kinematics, the interaction…
We present measurements of the total and differential cross sections for near-threshold J/$\psi$ photoproduction obtained with the CLAS12 detector at the Thomas Jefferson National Accelerator Facility. The results are based on data…
Photoproduction of $J/\psi$ is considered including the color-octet contributions from the various partial wave states, $^{2S+1}L_J$ = $^1S_0$, $^3S_1$ and $^3P_J$. The production cross section depends on three new nonperturbative…
We use perturbative QCD, beyond the leading $\ln Q^2$ approximation, to show how measurements of diffractive $J/\psi$ production at HERA can provide a sensitive probe of the gluon density of the proton at small values of Bjorken $x$. We…
We study the $J/\psi$ photoproduction from nuclei in the near-threshold beam energy region of $E_{\gamma}$=5--11 GeV within the nuclear spectral function approach by considering incoherent direct (${\gamma}N \to {J/\psi}N$) and two-step…
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…
One of the outstanding problems in J/\psi physics is a systematic understanding of the differential photo-production cross section dsigma/dz(gamma + p -> J/psi + X), where z= E_psi/E_gamma in the proton rest frame. The theoretical…
We consider the reaction $\gamma p \to M p$, with M being either a $\Phi$ or a $J/\Psi$ meson, within perturbative QCD treating the proton as a quark-diquark system. The phenomenological couplings of gauge bosons to (spatially extended)…
The near-threshold photo- and electroproduction of heavy vector quarkonia off the proton provides direct access to its gluonic structure. In particular, the cross section for $J/\Psi$ photoproduction near threshold is governed by the…
We present a nonperturbative QCD calculation of elastic $J/\psi$ meson production in photon-proton scattering at high energies. Using light cone wave functions of the photon and vector mesons, and the framework of the model of the…
The photoproduction of $J/\psi$ meson off the nucleon is investigated within a dynamical model approach based on a Hamiltonian which describes the reaction mechanisms of the Pomeron exchange, meson exchange, and direct $J/\psi$ radiation…
We study the photoproduction of the vector mesons $\Phi$ and $J/\Psi$ off a proton in the kinematical regime of large energies and scattering angles within the framework of perturbative QCD. Our investigations are based on the hard…
The cross section for the photoproduction of large-p_T J/psi mesons at HERA is calculated at next-to-leading order, adopting a perturbative approach to describe the fragmentation of charm quarks and gluons into J/psi mesons. We treat the…
The amplitude for $\gamma p \to V p$, where $V$ is a $J/\psi$ or $\Upsilon$ ground state or excited vector meson, is calculated in a pQCD $k_{T}$-factorization approach. We use this amplitude to predict the cross section for exclusive…
We compare the relative importance of different mechanisms for polarized $J/\psi$ production in semi-inclusive deep inelastic scattering processes at large $Q^2$. The transverse momentum dependent (TMD) factorization framework and…
We study J/psi photoproduction via fragmentation at next-to-leading order in the QCD-improved parton model, using the nonrelativistic factorization formalism proposed by Bodwin, Braaten, and Lepage. We consider direct and resolved…
Inelastic photoproduction of $J/\psi$ particles at high energies is one of the processes to determine the gluon distribution in the nucleon. The QCD radiative corrections to the color-singlet model of this reaction have recently been…