Charm quark–antiquark correlations in photon–proton scattering

Abstract

Correlation of charm quark -charm antiquark in γp scattering are calculated in the k t -factorization approach. We apply different unintegrated gluon distributions (uGDF) used in the literature. The results of our calculations are compared with very recent experimental results from the FOCUS collaboration. The CCFM uGDF developed recently by Kwieciński et al. gives a good description of the data. New observables are suggested for future studies. Predictions and perspectives for the HERA energies are presented.

Inclusive production ofJ/ψmeson in proton-proton collisions at BNL RHIC

“…These grids are then used via a two-dimensional interpolation in the spaces (x 1 , k 2 1,t ) and (x 2 , k 2 2,t ) associated with each of the two incoming partons. The Kwieciński unintegrated parton distributions were used recently in applications to cc photoproduction [35], cc correlations in nucleon-nucleon collisions [25], production of gauge bosons [36], production of Standard Model Higgs boson [37], inclusive production of pions [38], production of direct photons [39]. Good agreement with experimental data was obtained in the case when the data exist.…”

Charm photoproduction at DESY HERA:kTfactorization versus experimental data

“…It was demonstrated [11,22,23] that the leading-order off-shell matrix elements of the photon-gluon fusion |M| 2 (γg * → cc) combined with the noncollinear evolution of gluon densities in a proton A(x, k 2 T , µ 2 ) effectively simulate contribution from the charmed quark excitation subprocess cg → cg. Next, some c −c correlations in high energy γp scattering have been studied [24] and comparisons to the recently measured data of the FOCUS collaboration at Fermilab were made. In particular, it was shown that the analysis of the kinematical correlations of charmed quarks opens new possibilities for verifying models of non-collinear gluon evolution.…”

Scalar Higgs boson production in fusion of two off-shell gluons

“…Here the Feynman diagrams are calculated taking into account the virtualities and all possible polarizations of the incident partons. There are widely discussed applications of the k ⊥ -factorization approach to hard QCD processes like the J/ψ hadroproduction [6], charmonium production [7], heavy quark photo- [8,9] and hadroproduction [10], Higgs boson production [11,12]. Some exclusive processes in the framework of the k ⊥ -factorization approach are described in detail in [13].…”