5,220 research outputs found
Omega_{ccc} production via fragmentation at LHC
In the framework of the leading order of perturbative QCD and the
nonrelativistic quark-diquark model of baryons we have obtained fragmentation
function for c-quark to split into Omega_{ccc} baryon. It is shown that at LHC
one can expect 3.5 10^3 events with Omega_{ccc} at p_t>5 GeV/c and -1<y<1 per
year.Comment: LaTex, 5 pages and 2 figures. Talk presented at XIV Workshop on High
Energy Physics and Quantum Field Theory, Moscow, May 27 - June 4, 199
Prompt meson production at the LHC in the NRQCD with -factorization
In the framework of the -factorization, the prompt production of
mesons at the LHC conditions is studied. Our consideration is based on
the off-shell amplitudes for hard partonic subprocesses and on the
nonrelativistic QCD (NRQCD) formalism for the formation of bound states. We try
two latest parametrizations for noncollinear, or transverse momentum dependent
(TMD) gluon densities derived from the Catani-Ciafaloni-Fiorani-Marchesini
(CCFM) equation. We use the values of the nonperturbative matrix elements
obtained from a combined fit of the and differential cross
sections. Finally, we show an universal set of parameters that provides a
reasonable simultaneous description for all of the available data on the prompt
and production at the LHC.Comment: 5 pages, 2 figures, 3 table
Prompt charmonia production and polarization at LHC in the NRQCD with -factorization. Part III: meson
In the framework of -factorization approach, the production and
polarization of prompt mesons 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. Both the direct
production mechanism and feed-down contributions from and
decays are taken into account. The transverse momentum dependent (or
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 transverse momentum distributions and then
applied to describe the ATLAS and LHCb data on production and
polarization at , and TeV. We perform an estimation of
polarization parameters , and which determine spin density matrix and demonstrate that
treating the soft gluon emission as a series of explicit color-electric dipole
transitions within NRQCD leads to unpolarized production at high
transverse momenta, that is in qualitative agreement with the LHC data.Comment: 23 pages, 14 figures. arXiv admin note: substantial text overlap with
arXiv:1508.0548
First estimates of the wave function from the data on the production cross section
In the framework of perturbative QCD and nonrelativistic bound state
formalism, we calculate the production of and mesons at the
conditions of the CDF and LHCb experiments. We derive first estimations for the
wave function from a comparison with the available data.Comment: 3 pages, 1 figur
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
Heavy Quark Production in the Semihard QCD Approach at HERA and Beyond
Processes of heavy quark production at HERA, TEVATRON and THERA energies are
considered using the semihard ( factorization) QCD approach with emphasis
on the BFKL dynamics of gluon distributions.Comment: 4 pages, 5 figures, To appear in Proceedings of the 9th International
Workshop on Deep Inelastic Scattering (DIS2001), Bologna, Italy, 27 Apr. - 1
May 200
Particle Event Generator: A Simple-in-Use System PEGASUS version 1.0
PEGASUS is a parton-level Monte-Carlo event generator designed to calculate
cross sections for a wide range of hard QCD processes at high energy and
collisions, which incorporates the dynamics of transverse momentum
dependent (TMD) parton distributions in a proton. Being supplemented with
off-shell production amplitudes for a number of partonic subprocesses and
provided with necessary TMD gluon density functions, it produces weighted or
unweighted event records which can be saved as a plain data file or a file in a
commonly used Les Houches Event format. A distinctive feature of PEGASUS is an
intuitive and extremely user friendly interface, allowing one to easily
implement various kinematical cuts into the calculations. Results can be also
presented "on the fly" with built-in tool \textsc{pegasus plotter}. A short
theoretical basis is presented and detailed program description is given.Comment: 24 pages, 8 figure
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