Related papers: Relativistic correction to gluon fragmentation fun…
We have computed semi-inclusive spin asymmetries for proton and deuteron targets including next to leading order (NLO) QCD corrections and contributions coming from the target fragmentation region. These corrections have been estimated…
Within the framework of nonrelativistic QCD (NRQCD) factorization, we investigate the relativistic corrections to the production of double $B_c$ mesons in $e^+e^-$ annihilation. The study covers center-of-mass energies from the production…
We report the recent progress in the studies of D-wave heavy quarkonia production from gluon fragmentation at the Tevatron and in Z^0 decays, and the D-wave charmonia production in B decays. We show that the color-octet contributions are of…
The three-gluon contribution to $J/\psi$ hadroproduction is calculated within perturbative QCD in the $k_T$ factorization framework. This mechanism involves double gluon density and enters at a non-leading twist, but it is enhanced at large…
In this letter we address issues involved in quarkonium production near the boundaries of phase space. It is shown that higher-order non-perturbative contributions are enhanced in this kinematic region and lead to a breakdown of the…
In this work we derive three sets of non-perturbative fragmentation functions, with uncertainties, for $B$-hadrons, $J/\psi$'s and muons resulting from semileptonic $B$ decays. All three sets are with next-to-next-to leading order accuracy…
Non-relativistic QCD (NRQCD) is used to calculate the relativistic correction to the amplitude for exclusive photoproduction of vector Quarkonia in the near-threshold region within the generalized parton distribution (GPD) framework. The…
The fragmentation functions for gluons to split into P-wave heavy quarkonium states are calculated to leading order in the QCD coupling constant. Long-distance effects are factored into two nonperturbative parameters: the derivative of the…
Since an old observation by Beenakker et al, the evaluation of QCD processes in dimensional reduction has repeatedly led to terms that seem to violate the QCD factorization theorem. We reconsider the example of the process gg->ttbar and…
We include the $\eta_c$ meson into the $\eta$-$\eta'$-$G$ mixing formalism constructed in our previous work, where $G$ represents the pseudoscalar gluball. The mixing angles in this tetramixing matrix are constrained by theoretical and…
We derive the gluon initiated contribution to the initial condition for the perturbative fragmentation function of a heavy quark through order O(\alpha_s^2) in the MS-bar scheme. This result is needed for the resummation with…
We propose a new formula for extracting the polarized gluon distribution $\Delta g$ in the proton from the large--$p_T$ light hadron pair production in deep inelastic semi-inclusive reactions. Though the process dominantly occurs via…
We show that the twist-2 light-cone wave-functions of eta_c and J/\psi can be factorized with nonrelativistic QCD(NRQCD) at one-loop level, where the nonperturbative effects are represented by NRQCD matrix elements. The factorization is…
The rapid thermalization of quarks and gluons in the initial stages of relativistic heavy-ion collisions is treated using analytic solutions of a nonlinear diffusion equation with schematic initial conditions, and for gluons with boundary…
We perform a QCD analysis for the radiative decay of a heavy $^3S_1$ quarkonium into the tensor meson $f_2(1270)$. We make an attempt to separate the nonperturbative effect related to the quarkonium and that related to the tensor meson, the…
The production cross sections of $e^+e^- $ to a heavy quarkonium with $C$-parity even $S-$wave and $P-$wave associated with a photon are analyzed in the framework of non-relativistic Quantum Chromodynamics(NRQCD) factorization formalism.…
A first theoretical study for neutrino-induced diffractive productions of heavy pseudoscalar-mesons, \eta_c and \eta_b, off a nucleon is performed based on factorization formalism in QCD. We evaluate the forward diffractive production cross…
By expanding functions of parton fragmentation into a heavy hadron in the inverse of the heavy quark mass $m_Q$ we attempt to factorize them into perturbative- and nonperturbative parts. In our approach the nonperturbative parts can be…
We discuss the very rare, exclusive hadronic decays of a Z boson into a meson and a photon. The QCD factorization approach allows to organize the decay amplitude as an expansion in powers of $\Lambda_{\rm QCD}/m_Z\,$, where the leading…
We address the unphysical energy dependence of quarkonium-hadroproduction cross sections at Next-to-Leading Order (NLO) in alpha_S which we attribute to an over-subtraction in the factorisation of the collinear singularities inside the PDFs…