Related papers: Colour Octet effects in Quarkonium Physics
J/psi production in top quark rare decays is investigated under the framework of NRQCD factorization formalism. Various production channels are studied, and we find that the contributions from the color-singlet quark fragmentation and the…
The potential of decays of mesons containing heavy quarks [including $B$ mesons and the $\Upsilon(1S)$] for producing final states of matter with unusual quark configurations, such as $q q \bar q \bar q$ or $q q q q \bar q$, is…
We calculated the color-octet contribution to the $\ps$ hadroproduction at fixed target energies $\sqrt(s)\simeq40$ GeV. We consider the $\ps$ production with transverse momenta which can not be explained by primordial motion of partons,…
In the paper, the inclusive production of heavy quarkonium $\eta_Q$ ($Q=b$ or $c$) via $Z$ boson decays within the framework of nonrelativistic QCD effective theory are studied. The contributions from the leading color-singlet and…
The ATLAS detector at CERN's LHC is preparing to take data from the first proton-proton collisions expected in the next few months. We report on the analysis of simulated data samples for production of heavy Quarkonium states J/psi and…
Using Nonrelativistic QCD on the lattice we studied the mass spectrum of quarkonium systems nonperturbatively for a range of the bar quark mass. We determined two products of the matrix elements involved in quarkonium decays and studied the…
Two-pion transitions in charmonium and bottomonium are considered with the leading relativistic effects taken into account. The contribution of the chromo- magnetic interaction of the charmed quarks to the amplitude of the decay $\psi(2S)…
A factorization theorem for $P$-wave quarkonium production, recently derived by Bodwin, Braaten, Yuan and Lepage, is applied to $\Upsilon \to \chi_{cJ} + X$, where $\chi_{cJ}$ labels the ${}^3 P_J$ charmonium states. The widths for…
Approximately taking into account the higher-order effects due to multiple-gluon initial-state radiation, we extract from the latest Tevatron data of prompt J/psi hadroproduction the leading colour-octet matrix elements within the…
Motivated by the ${\pi}{\pi}$ puzzle in nonleptonic $B$ decays in the time of high-precision and huge-data for particle physics, we restudy the $\overline{B}$ ${\to}$ ${\pi}{\pi}$ decays with QCD factorization approach. An additional…
We investigate the theoretical uncertainties of $P$-wave charmonium decays into two pions, $\chi_{\c J}\rightarrow \pi^+\pi^-$, $\pi^0\pi^0$. Constraining the pion distribution-amplitude from the recent precise data on $F_{\pi\gamma}(Q^2)$,…
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…
We update the study of the QCD corrections to direct J/psi and Upsilon hadroproduction in association with a photon in the QCD-based approach of the Colour-Singlet (CS) Model. After comparison with the recent full next-to-leading-order…
We calculate the cross section of inclusive direct J/psi photoproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics, for the first time including the full relativistic corrections…
The suppression of quarkonium production in nucleus-nucleus collisions was originally proposed as a signal of colour deconfinement. Strong ``anomalous" J/\psi suppression in Pb-Pb collisions has been reported at this Conference by the NA50…
Charmonium production and absorption in heavy ion collisions is studied with the Ultrarelativisitic Quantum Molecular Dynamics model. We compare the scenario of universal and time independent color-octet dissociation cross sections with one…
We present the calculation of O(as^2 aem) corrections to heavy-quarkonium total photoproduction cross-sections. Results are given for the colour-octet component of S and P waves. The calculation is performed using covariant projectors in…
The production of quarkonium is an important testing ground for QCD calculations. The J/\psi\ and \Upsilon\ production cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 7~TeV with the ATLAS detector at…
We present the results of our analysis on charmonia ($J/\psi$ and $\psi'$) hadroproduction taking into account higher-order QCD effects induced by initial-state radiation in a Monte Carlo framework, with the colour-octet mechanism…
The hierarchy of long-distance matrix elements (MEs) for quarkonium production depends on their scaling with the velocity $v$ of the heavy quark in the bound state. Ranges for the velocities in various bound states and uncertainties of…