4,584 research outputs found
Heavy quark production in the semihard QCD approach at THERA
In the framework of the semihard ( factorization) QCD approach, we
consider the photoproduction of D* mesons associated with two hadron jets and
the D* production in DIS at THERA conditions with the emphasis on the BFKL and
CCFM dynamics of gluon distributions. In the photoproduction of D* mesons the
attention is focused on the variable , which is the fraction of the
photon momentum contributed to a pair of jets with largest . We show that
our theoretical results are sensitive to the BFKL type dynamics which may be
investigated at THERA energies. We also discuss possible effect of \J/\psi
meson spin alignement, which is thought to be a vivid manifestation of gluon
off-shellness.Comment: 9 pages, 3 figures, in "The THERA Book", DESY-LC-REV-2001-06
Prompt charmonia production and polarization at LHC in the NRQCD with kt-factorization. Part I: psi(2S) meson
In the framework of kt-factorization approach, the production and
polarization of prompt psi(2S) mesons in pp collisions at the LHC energies is
studied. Our consideration is based on the non-relativistic QCD formalism for
bound states and off-shell amplitudes for hard partonic subprocesses. The
transverse momentum dependent (unintegrated) gluon densities in a proton were
derived from Ciafaloni-Catani-Fiorani-Marchesini evolution equation or,
alternatively, were chosen in accordance with Kimber-Martin-Ryskin
prescription. The non-perturbative color-octet matrix elements were first
deduced from the fits to the latest CMS data on psi(2S) transverse momentum
distributions and then applied to describe the ATLAS and LHCb data on psi(2S)
production and polarization at 7 TeV. We perform the estimation of polarization
parameters , and which
determine psi(2S) spin density matrix and demonstrate that taking into account
the off-shellness of initial gluons in the color-octet contributions leads to
unpolarized psi(2S) production at high transverse momenta, that is in
qualitative agreement with the LHC data.Comment: 19 pages, 8 figures. arXiv admin note: text overlap with
arXiv:1108.285
TMD PDFs in Drell-Yan lepton pair production at LHC
We consider the transverse momentum dependent (TMD) quark densities of the
proton which are very important ingredients for unpolarized Drell-Yan (DY)
lepton pair production. We calculate the TMD sea quark density as a convolution
of the Catani-Ciafaloni-Fiorani-Marchesini (CCFM)-evolved gluon distribution
and the TMD gluon-to-quark splitting function. Based on the production amplitude , calculated by taking into account the effective
- vertex, we analyze the distributions on the dilepton invariant mass,
transverse momentum and rapidity and specific angular correlations between the
produced leptons as measured by the CMS, ATLAS and LHCb collaborations. We
briefly duscuss also the process of assiciated lepton pair and jet production
in collisions at the LHC.Comment: Talk presented at International Workshop on Diffraction in
High-Energy Physics, Diffraction-201
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