6,425 research outputs found
Momentum spectra of charmonium produced in a quark-gluon plasma
We calculate rapidity and transverse momentum distributions of charmonium
formed in high energy heavy ion collsions from incoherent recombination of
charm quarks. The results are very sensitive to the corresponding distributions
of the charm quarks, and thus can serve as a probe of the state of matter
produced in the heavy ion collision. At one extreme we generate a set of charm
pair momenta directly from pQCD amplitudes, which are appropriate if one can
neglect interaction of the quarks with the medium. At the other extreme we
generate momenta of charm quarks in thermal equilibrium with the expanding
medium, appropriate for an extremely strong interaction. Explicit predictions
are made for J/Psi formation in Au-Au interactions at RHIC. We find that for
the case in which charm quark momenta are unchanged from the pQCD production
calculation, both the rapidity and transverse momentum spectra of the formed
J/Psi are substantially narrower than would be anticipated in scenarios which
do not include the in-medium formation. In particular, the average transverse
momentum of the J/Psi will exhibit a non-monotonic behavior in the progression
from p-p to p-A to A-A interactions.Comment: Final published version, clarifying remarks adde
QCD tools for the LHC
This contribution provides a pedagogical introduction to and review of the
current status and ongoing progress in the development of Monte Carlo tools for
the calculation and simulation of high-Q^2 processes in hadronic collisions.Comment: Talk at the International Workshop on QCD: QCD@Work 2003 - Conversano
(Italy) 14-18 June 2003 (eConf C030614), 9 page
The saga of bottom production in proton-antiproton collisions
I review here the history of bottom quark cross section measurements and
theoretical predictions. Starting form the early days of UA1, and going through
the sequence of the large excesses reported during run 0 and I at the Tevatron
by CDF and D0, I summarize how both data and theory have evolved in time,
thanks to improved experimental techniques, more data, and improved control
over the main ingredients of the theoretical calculations. I conclude with the
discussion of the preliminary data from run II, which appear to finally give a
satisfactory picture of the data vs theory comparison.Comment: 14 pages, Presented at the 2004 Hadron Collider Physics Workshop,
East Lansing, MI, June 200
Phenomenology of Quarkonium Production in Hadronic Collisions
We review recent progress made in the theory of quarkonium production in
hadronic collisions.Comment: 15 pages, Latex, 6 PS figures included via psfig. To appear in the
Proceedings of the Xth Topical Workshop on Proton--Antiproton Collider
Physics, Batavia, IL, USA, May 199
LHC physics: the first one--two year(s)
We discuss the strategy to commission the LHC experiments and understand
standard physics at sqrt{s}=14TeV before data taking starts and in the early
phases of the LHC operation. In particular, we review the various steps needed
to understand and calibrate the ATLAS and CMS detectors, from construction
quality checks, to beam tests, to cosmics runs, to first collisions. We also
review the preparation and tuning of Monte Carlo tools, and present a few
examples of physics goals for integrated luminosities of up to a few inverse
fb.Comment: Proceedings of the 2nd Italian Workshop on the physics of Atlas and
CM
Observables for possible QGP signatures in central pp collisions
Proton-proton (pp) data show collective effects, such as long-range azimuthal
correlations and strangeness enhancement, which are similar to phenomenology
observed in heavy ion collisions. Using simulations with and without explicit
existing models of collective effects, we explore new ways to probe pp
collisions at high multiplicity, in order to suggest measurements that could
help identify the similarities and differences between large- and small-scale
collective effects. In particular, we focus on the properties of jets produced
in ultra-central pp collisions in association with a Z boson. We consider
observables such as jet energy loss and jet shapes, which could point to the
possible existence of an underlying quark-gluon plasma, or other new dynamical
effects related to the presence of large hadronic densities.Comment: 32 pages, 20 figure
Neutrino masses and baryogenesis in SO(10) unified theories
We report on some phenomenological implications of a class of unified models
based on SO(10) gauge group, with intermediate symmetry group containing
SU(2)_R. Interesting predictions for neutrino masses are discussed, which are
relevant both for solar neutrino and dark matter problems, as well as a model
for the formation of the baryon asymmetry of the universe required by
primordial nucleosynthesis.Comment: Latex 16 pages, 1 ps figure. Appeared in Proceedings of seventh
International Workshop on Neutrino Telescopes, Venezia February 27 - March 1
1996, Editor M. Baldo Ceoli
Comments on claimed risk from metastable black holes
In a recent note, arXiv:0808.1415, it was argued that a hypothetical
metastable black hole scenario could pose collider risk not excluded by our
previous study. We comment on inconsistency of this proposed scenario.Comment: 3 pages; comment on arXiv:0808.141
Re: "Soft tissue profile after distal molar movement with a pendulum K-loop appliance versus cervical headgear: a statistical consideration", by O. Polat-Ozsoy, A. Gokcelik, A. Gungor-Acar, B.H. Kircelli. The Angle Orthodontist 2008;78(Mar):317-323.
The Resummation of Soft Gluon in Hadronic Collisions
We compute the effects of soft gluon resummation for the production of high
mass systems in hadronic collisions. We carefully analyse the growth of the
perturbative expansion coefficients of the resummation formula. We propose an
expression consistent with the known leading and next-to-leading resummation
results, in which the coefficients grow much less than factorially. We apply
our formula to Drell--Yan pair production, heavy flavour production, and the
production of high invariant mass jet pairs in hadronic collisions. We find
that, with our formula, resummation effects become important only fairly close
to the threshold region. In the case of heavy flavour production we find that
resummation effects are small in the experimental configurations of practical
interest.Comment: 45 pages, Latex, epsfig, 10 figures. Minor corrections to text,
notation and references. The previously quoted HERAb NLO bottom production
cross section was wrong, and it has been fixed. Accepted for Publication on
Nucl. Phys.
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