1,223 research outputs found
Diffractive Higgs boson photoproduction in peripheral collisions
An alternative process is proposed for the diffractive Higgs boson production
in peripheral collisions, exploring it through the photon-proton
interaction by Double Pomeron Exchange. It is estimated the event rate of the
diffractive Higgs production in central rapidity for Tevatron and LHC energies,
being of the order of 1 fb, in agreement to the predictions from other
diffractive processes. The results are confronted with those obtained from a
similar approach of the Durham group.Comment: 4 pages, 7 figures, contribution to the proceedings of II Latin
American Workshop on High Energy Physics [IILAWHEP], 3-7 Dec. 2007, Sao
Miguel das Missoes, Brazi
Single and Central Diffractive Higgs Production at the LHC
The single and central diffractive production of the Standard Model Higgs
boson is computed using the diffractive factorization formalism, taking into
account a parametrization for the Pomeron structure function provided by the H1
Collaboration. We compute the cross sections at NLO accuracy for the gluon
fusion process, since it is the leading mechanism for the Higgs boson
production. The gap survival probability is also introduced to include the
rescattering corrections due to spectator particles present in the interaction.
The diffractive ratios are predicted for proton-proton collisions at the LHC,
since the beam luminosity is favorable to the Higgs boson detection. These
results provide updated estimations for the fraction of single and central
diffractive events in the LHC kinematical regime.Comment: To appear in the proceedings of Diffraction 2010: International
Workshop on Diffraction in High Energy Physics, Otranto, Italy, 10-15 Sep
201
Soft and hard QCD dynamics in hadroproduction of charmonium
Both hard and soft QCD dynamics are important in charmonium production, as
presented here through a next-to-leading order QCD matrix element calculation
combined with the colour evaporation model. Observed and
distributions of in hadroproduction at fixed target and
collider energies are reproduced. Quite similar results can also be obtained in
a more phenomenologically useful Monte Carlo event generator where the
perturbative production of \ccbar pairs is instead obtained through leading
order matrix elements and the parton shower approximation of the higher order
processes. The soft dynamics may alternatively be described by the soft colour
interaction model, originally introduced in connection with rapidity gaps. We
also discuss the relative rates of different charmonium states and introduce an
improved model for mapping the continuous \ccbar mass spectrum on the physical
charmonium resonances.Comment: 21 pages, 13 eps figure
Soft and hard QCD in charmonium production
Hard and soft QCD dynamics are both important in charmonium hadroproduction,
as presented here through a next-to-leading order QCD matrix element
calculation combined with the colour evaporation model. Observed and
distributions of in hadroproduction are reproduced. Quite
similar results can also be obtained with a Monte Carlo event generator where
\ccbar pairs are instead produced through leading order matrix elements and the
parton shower approximation of higher order processes. The soft dynamics may
alternatively be described by the soft colour interaction model. We also
discuss the relative rates of different charmonium states and introduce an
improved model for mapping the continuous ccbar mass spectrum on the physical
charmonium resonances.Comment: Presented at Pan American Advanced Studies Institute (PASI 2002),
Campos do Jord\~ao, Brazil, January 7-18, 200
Aspects of the Unitarized Soft Multipomeron Approach in DIS and Diffraction
We study in detail the main features of the unitarized Regge model (CFKS),
recently proposed to describe the small- domain. It takes into account a
two-component description with two types of unitarized contributions: one is
the multiple pomeron exchange contribution, interacting with the large dipole
configurations, and the other one consists of a unitarized dipole cross
section, describing the interaction with the small size dipoles. We analyze the
ratio between soft and hard pieces as a function of the virtuality, and also
compare the resulting dipole cross section to that from the saturation model.
Diffraction dissociation is also considered, showing the scaling violations in
diffractive DIS and estimating the corresponding logarithmic slope.Comment: 14 pages, 5 postscript figures. Version to be published in Eur. Phys.
J.
Unitarity Corrections to the Proton Structure Functions through the Dipole Picture
We study the dipole picture for the description of the deep inelastic
scattering, focusing on the structure functions which are driven directly by
the gluon distribution. One performs estimates using the effective dipole cross
section given by the Glauber-Mueller approach in QCD, which encodes the
corrections due to the unitarity effects associated with the saturation
phenomenon. We also address issues about frame invariance of the calculations
when analysing the observables.Comment: 16 pages, 8 figures. Version to be published in Phys. Rev.
Color Evaporation and Elastic Photoproduction at DESY HERA
The diffractive photoproduction of vector mesons is usually described
considering the two-gluon (Pomeron) exchange, non-diagonal parton distributions
and the contribution of the real part to the cross section. In this letter we
analyze the diffractive photoproduction of the at HERA using an
alternative model, the Color Evaporation Model (CEM), where the cross section
is simply determined by the boson-gluon cross section and an assumption for the
production of the colorless state. We verify that, similarly to the
case, the HERA data for this process can be well described by the CEM.
Moreover, we propose the analyzes of the ratio to discriminate between the distinct approaches.Comment: 7 pages, 3 figures, accepted for publication in PRD (Brief Reports
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