1,853 research outputs found
Results on Photon Production in Au+Au Collisions at RHIC
The status of the search for direct photons in Au+Au collisions at sqrt{s_NN}
= 130 GeV and sqrt{s_NN} = 200 GeV with the PHENIX experiment is presented.
Within errors, no excess of direct photons was found in a first analysis pass
done on a limited data set. Significantly reduced systematic and statistical
uncertainties are expected in future analyses.Comment: 4 pages, 3 figures. Talk presented at the Quark Matter 2002
conference, Nantes, France, July 18-24, 2002. To appear in the proceedings
(Nucl. Phys. A
Memory effects in radiative jet energy loss
In heavy-ion collisions the created quark-gluon plasma forms a quickly
evolving background, leading to a time dependent radiative behavior of high
momentum partons traversing the medium. We use the Schwinger Keldysh formalism
to describe the jet evolution as a non-equilibrium process including the
Landau-Pomeranschuk-Migdal effect. Concentrating on photon emission, a
comparison of our results to a quasistatic calculation shows good agreement,
leading to the conclusion that the radiative behavior follows the changes in
the medium almost instantaneously
Bulk Properties of Pb-Pb collisions at sqrt(sNN) = 2.76 TeV measured by ALICE
Global variables, such as the charged particle multiplicity and the
transverse energy are important observables to characterize Relativistic Heavy
Ion collisions and to constrain model calculations. The charged particle
multiplicity dNch/deta and transverse energy dET/deta are measured at sqrt(sNN)
= 2.76 TeV in Pb-Pb collisions as a function of centrality and in pp
collisions. The fraction of inelastic cross section seen by the ALICE detector
is calculated either using a Glauber model or the data corrected by simulations
of nuclear and electromagnetic processes, or data collected with a minimum bias
interaction trigger. The centrality, defined by the number of nucleons
participating in the collision, is obtained, via the Glauber model, by relating
the multiplicity distributions of various detectors in the ALICE Central Barrel
and their correlation with the spectator energy measured by the Zero-Degree
Calorimeters. The results are compared to corresponding results obtained at the
significantly lower energies of the BNL AGS, the CERN SPS, and the BNL RHIC,
and with models based on different mechanisms for particle production in
nuclear collisions. Particular emphasis will be given to a discussion on
systematic studies of the dependence of the centrality determination on the
details of the Glauber model, and the validity of the Glauber model at
unprecedented collision energies.Comment: Proceedings of the XXII International Conference on Ultrarelativistic
Nucleus-Nucleus Collisions Quark Matter 2011, submitted to J. Phys. G: Nucl.
Part. Phys. 8 pages, 7 (multi)figure
Are High-pT Pions Suppressed in Pb+Pb Collisions at sqrt(sNN) = 17.3 GeV?
Transverse momentum spectra of neutral pions in the range 0.7 < pT < 3.2
GeV/c have been measured at 2.3 < eta < 3.0 by the WA98 experiment in p+C and
p+Pb collisions at sqrt(sNN) = 17.3 GeV. Scaled by the number of
nucleon-nucleon collisions (Ncoll) the pi^0 yields in p+C and p+Pb at pT ~ 2.0
- 2.5 GeV/c are higher than the respective yields in central Pb+Pb collisions
with Npart > 300. This observation is qualitatively consistent with
expectations from parton energy loss.Comment: 4 pages, 3 figures, To appear in the proceedings of the Quark Matter
2006 conference, Shanghai, China, 14-20 Nov 200
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