20,207 research outputs found
Looking at the photoproduction of massive gauge bosons at the LHeC
In this contribution we report on the investigation of the photoproduction of
W and Z bosons in the planned electron-proton/nucleus collider, the LHeC. The
production cross sections and the number of events are provided and theoretical
uncertainties are discussed. We also analyze the sensitivity of the LHeC
experiment to physics beyond Standard Model by studying the role played by
anomalous WWgamma coupling in the presented process.Comment: Contribution to the proceedings of the XXI International Workshop on
Deep-Inelastic Scattering and Related Subjects (DIS2013), Marseille, 22-26
April 201
Gluino production in ultrarelativistic heavy ion collisions and nuclear shadowing
In this article we investigate the influence of nuclear effects in the
production of gluinos in nuclear collisions at the LHC, and estimate the
transverse momentum dependence of the nuclear ratios and . We
demonstrate that depending on the magnitude of the nuclear effects, the
production of gluinos could be enhanced, compared to proton-proton collisions.
The study of these observables can be useful to determine the magnitude of the
shadowing and antishadowing effects in the nuclear gluon distribution.
Moreover, we test different SPS scenarios, corresponding to different soft SUSY
breaking mechanisms, and find that the nuclear ratios are strongly dependent on
that choice.Comment: 7 pages, 5 figures; results and discussions changed/added. Accepted
for publication in Physical Review
Quarkonium plus prompt-photon associated hadroproduction and nuclear shadowing
The quarkonium hadroproduction in association with a photon at high energies
provides a probe of the dynamics of the strong interactions as it is dependent
on the nuclear gluon distribution. Therefore, it could be used to constrain the
behavior of the nuclear gluon distribution in proton-nucleus and
nucleus-nucleus collisions. Such processes are useful to single out the
magnitude of the shadowing/antishadowing effects in the nuclear parton
densities. In this work we investigate the influence of nuclear effects in the
production of JPsi + photon and Upsilon + photon and estimate the transverse
momentum dependence of the nuclear modification factors. The theoretical
framework considered in the JPsi (Upsilon) production associated with a direct
photon at the hadron collider is the non-relativistic QCD (NRQCD) factorization
formalism.Comment: 8 pages, 4 figures. Final version to be published in European
Physical Journal
Inclusive and exclusive dilepton photoproduction at high energies
In this work we investigate the inclusive and exclusive photoproduction of
dileptons, which is relevant for the physics programme to be studied in the
proposed electron-proton collider, the LHeC. In the inclusive case, the process
is sensitive to the parton distribution functions in the photon whereas the
exclusive channel is connected to the small- QCD dynamics. For the latter,
we investigate the role played by saturation physics at a very high energy
scenario. The estimates for production cross sections and the number of events
are presented.Comment: 5 pages, version to be published in Physical Review
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
From cellular properties to population asymptotics in the Population Balance Equation
Proliferating cell populations at steady state growth often exhibit broad
protein distributions with exponential tails. The sources of this variation and
its universality are of much theoretical interest. Here we address the problem
by asymptotic analysis of the Population Balance Equation. We show that the
steady state distribution tail is determined by a combination of protein
production and cell division and is insensitive to other model details. Under
general conditions this tail is exponential with a dependence on parameters
consistent with experiment. We discuss the conditions for this effect to be
dominant over other sources of variation and the relation to experiments.Comment: Exact solution of Eq. 9 is adde
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