7,092 research outputs found
Probing the gluon density of the proton in the exclusive photoproduction of vector mesons at the LHC: A phenomenological analysis
The current uncertainty on the gluon density extracted from the global parton
analysis is large in the kinematical range of small values of the Bjorken -
variable and low values of the hard scale . An alternative to reduces this
uncertainty is the analysis of the exclusive vector meson photoproduction in
photon - hadron and hadron - hadron collisions. This process offers a unique
opportunity to constrain the gluon density of the proton, since its cross
section is proportional to the gluon density squared. In this paper we consider
current parametrizations for the gluon distribution and estimate the exclusive
vector meson photoproduction cross section at HERA and LHC using the leading
logarithmic formalism. We perform a fit of the normalization of the
cross section and the value of the hard scale for the process and demonstrate
that the current LHCb experimental data are better described by models that
assume a slow increasing of the gluon distribution at small - and low
.Comment: 8 pages, 6 figures, 1 table. Version published in European Physical
Journal
Photon and Pomeron -- induced production of Dijets in , and collisions
In this paper we present a detailed comparison of the dijet production by
photon -- photon, photon -- pomeron and pomeron -- pomeron interactions in
, and collisions at the LHC energy. The transverse
momentum, pseudo -- rapidity and angular dependencies of the cross sections are
calculated at LHC energy using the Forward Physics Monte Carlo (FPMC), which
allows to obtain realistic predictions for the dijet production with two
leading intact hadrons. We obtain that \gamma \pom channel is dominant at
forward rapidities in collisions and in the full kinematical range in the
nuclear collisions of heavy nuclei. Our results indicate that the analysis of
dijet production at the LHC can be useful to test the Resolved Pomeron model as
well as to constrain the magnitude of the absorption effects.Comment: 11 pages, 6 figures, 1 table. Improved and enlarged version published
in European Physical Journal
Production of exotic charmonium in interactions at hadronic colliders
In this paper we investigate the Exotic Charmonium (EC) production in interactions present in proton-proton, proton-nucleus and
nucleus-nucleus collisions at the CERN Large Hadron Collider (LHC) energies as
well as for the proposed energies of the Future Circular Collider (FCC). Our
results demonstrate that the experimental study of these processes is feasible
and can be used to constrain the theoretical decay widths and shed some light
on the configuration of the considered multiquark states.Comment: 7 pages, 2 figures, 3 tables. v2: Revised version published in
Physical Review
On the rapidity dependence of the average transverse momentum in hadronic collisions
The energy and rapidity dependence of the average transverse momentum
in and collisions at RHIC and LHC energies are
estimated using the Colour Glass Condensate (CGC) formalism. We update previous
predictions for the - spectra using the hybrid formalism of the CGC
approach and two phenomenological models for the dipole - target scattering
amplitude. We demonstrate that these models are able to describe the RHIC and
LHC data for the hadron production in , and collisions at GeV. Moreover, we present our predictions for and
demonstrate that the ratio decreases with the rapidity and has a behaviour similar to that
predicted by hydrodynamical calculations.Comment: 11 pages, 7 figures; revised version: new results for the average
transverse momentum at partonic level added in fig. 4; Results and Discussion
section has been improved and enlarge
Testing the running coupling -factorization formula for the inclusive gluon production
The inclusive gluon production at midrapidities is described in the Color
Glass Condensate formalism using the - factorization formula, which was
derived at fixed coupling constant considering the scattering of a dilute
system of partons with a dense one. Recent analysis demonstrated that this
approach provides a satisfactory description of the experimental data for the
inclusive hadron production in collisions. However, these studies
are based on the fixed coupling - factorization formula, which does not
take into account the running coupling corrections, which are important to set
the scales present in the cross section. In this paper we consider the running
coupling corrected - factorization formula conjectured some years ago and
investigate the impact of the running coupling corrections on the observables.
In particular, the pseudorapidity distributions and charged hadrons
multiplicity are calculated considering , and
collisions at RHIC and LHC energies. We compare the corrected running coupling
predictions with those obtained using the original - factorization
assuming a fixed coupling or a prescription for the inclusion of the running of
the coupling. Considering the Kharzeev - Levin - Nardi unintegrated gluon
distribution and a simplified model for the nuclear geometry, we demonstrate
that the distinct predictions are similar for the pseudorapidity distributions
in collisions and for the charged hadrons multiplicity in
collisions. On the other hand, the running coupling corrected -
factorization formula predicts a smoother energy dependence for in
collisions.Comment: 9 pages and 4 figure
About possible contribution of intrinsic charm component to inclusive spectra of charmed mesons
We calculate differential energy spectra (-distributions) of charmed
particles produced in proton-nucleus collisions, assuming the existence of
intrinsic heavy quark components in the proton wave function. For the
calculation, the recently proposed factorization scheme is used, based on the
Color Glass Condensate theory and specially suited for predictions of a
production of particles with large rapidities. It is argued that the intrinsic
charm component can, if it exists, dominate in a sum of two components,
intrinsic + extrinsic, of the inclusive spectrum of charmed particles produced
in proton-nucleus collisions at high energies, in the region of medium ,
, and can give noticeable contribution to atmospheric fluxes
of prompt muons and neutrinos.Comment: 10 pages, 4 figures. Version published in J. Phys. G
The MIPSGAL View of Supernova Remnants in the Galactic Plane
We report the detection of Galactic supernova remnants (SNRs) in the mid-infrared (at 24 and 70 μm), in the coordinate ranges 10° < l < 65° and 285° < l < 350°, |b| < 1°, using MIPS aboard the Spitzer Space Telescope. We search for infrared counterparts to SNRs in Green's catalog and identify 39 out of 121, i.e., a detection rate of about 32%. Such a relatively low detection fraction is mainly due to confusion with nearby foreground/background sources and diffuse emission. The SNRs in our sample show a linear trend in [F_8/F_(24)] versus [F_(70)/F_(24)]. We compare their infrared fluxes with their corresponding radio flux at 1.4 GHz and find that most remnants have a ratio of 70 μm to 1.4 GHz which is similar to those found in previous studies of SNRs (with the exception of a few that have ratios closer to those of H II regions). Furthermore, we retrieve a slope close to unity when correlating infrared (24 and 70 μm) with 1.4 GHz emission. Our survey is more successful in detecting remnants with bright X-ray emission, which we find is well correlated with the 24 μm morphology. Moreover, by comparing the power emitted in the X-ray, infrared, and radio, we conclude that the energy released in the infrared is comparable to the cooling in the X-ray range
Quarkonium+ production in coherent hadron - hadron interactions at LHC energies
In this paper we study the ( and )
production in coherent hadron - hadron interactions at LHC energies.
Considering the ultrarelativistic protons as a source of photons, we estimate
the cross section using the
non-relativistic QCD (NRQCD) factorization formalism and considering different
sets of values for the matrix elements. Our results for the total cross sections and rapidity distributions at
and 14 TeV demonstrate that the experimental analysis of the
production at LHC is feasible.Comment: 6 pages, 3 figures, 1 table. Improved version with a new figure.
Version to be published in European Physical Journal
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