1,906 research outputs found
Dileptons from the nonequilibrium Quark-Gluon Plasma
According to the dynamical quasiparticle model (DQPM) -- matched to reproduce
lattice QCD results in thermodynamic limit, -- the constituents of the strongly
interacting quark-gluon plasma (sQGP) are massive and off-shell quasi-particles
(quarks and gluons) with broad spectral functions. In order to address the
electromagnetic radiation of the sQGP, we derive off-shell cross sections of
, and () reactions taking into account the effective propagators
for quarks and gluons from the DQPM. Dilepton production in In+In collisions at
158 AGeV is studied by implementing these processes into the
parton-hadron-string dynamics (PHSD) transport approach. The microscopic PHSD
transport approach describes the full evolution of the heavy-ion collision:
from the dynamics of quasi-particles in the sQGP phase (when the local energy
density is above GeV/fm) through hadronization and to the
following hadron interactions and off-shell propagation after the
hadronization. A comparison to the data of the NA60 Collaboration shows that
the low mass dilepton spectra are well described by including a collisional
broadening of vector mesons, while the spectra in the intermediate mass range
are dominated by off-shell quark-antiquark annihilation, quark Bremsstrahlung
and gluon-Compton scattering in the nonperturbative QGP. In particular, the
observed softening of the spectra at intermediate masses (1 GeV 3 GeV) is approximately reproduced.Comment: 8 pages, 8 figures, to be published in the Proceedings of the 26th
Winter Workshop on `Nuclear Dynamics', Ochto Rios, Jamaica, 2-9 January, 201
Elliptic and triangular flow of identified particles at ALICE
We report on the first measurements of elliptic and triangular flow for
charged pions, kaons and anti-protons in lead-lead collisions at 2.76 TeV
measured with the ALICE detector at the LHC. We compare the observed mass
splitting of differential elliptic flow at LHC energies to RHIC measurements at
lower energies and theory predictions. We test the quark coalescence picture
with the quark number scaling of elliptic and triangular flow.Comment: 4 pages, 5 figures, Quark Matter 2011 conference proceeding
Elliptic flow at high transverse momentum in Pb-Pb collisions at TeV with the ALICE experiment
An observable that can be used to better constrain the mechanism responsible
for the parton energy loss is the elliptic azimuthal event anisotropy, .
We report on measurements of for inclusive and identified charged
particles in Pb-Pb collisions at TeV recorded by the
ALICE experiment at the LHC. is presented for a wide range of particle
transverse momentum up to GeV/c. The particle is finite,
positive and approximately constant for GeV/c. The proton is
higher than that of the pion up to about GeV/c. The results are
compared to the measurements at lower energy reported by RHIC experiments.Comment: 4 pages, QM 2011 proceeding
A propeller flap for single-stage nose reconstruction in selected patients: supratrochlear artery axial propeller flap
The paramedian forehead flap is the gold standard technique for nose reconstruction. It requires two different surgical operations which prolonged the postoperative dressing and care. We present our 5-year experience with a propeller flap based on the supratrochlear artery, which allows one-stage transfer of the forehead skin to the nose without the need for pedicle division. This technique is indicated in a selected group of patients who are not suitable for multiple-stage reconstructions because they have concurrent medical conditions, reduced mobility, or live far away from specialized medical centers. We have renamed this procedure as supratrochlear artery axial propeller flap, from the acronym STAAP flap, to stress the axial, well known and constant, vascularization of the flap. In the past 5 years, we have been performing 25 STAAP flaps; full-thickness nasal reconstruction was performed in 11 cases. The patients were 16 males and 9 females, with a mean age of 79.5 years. All patients had multiple comorbidities. Complete flap survival was observed in 23 cases and healing was complete in 7 days. In two cases, there was a partial distal necrosis of the flap treated conservatively. Cosmetic results were good and the patient's satisfaction was significant. These results indicate that the STAAP flap is a reliable and useful technique in selected cases, as old or noncompliant patients who benefit from a one-stage technique of nose reconstructio
The Horn, Kink and Step, Dale: from few GeV to few TeV
Rich experimental data have been collected in heavy-ion collisions at high
energies to study the properties of strongly interacting matter. As the theory
of strong interactions, QCD, predicts asymptotic freedom, the created matter at
sufficiently high temperature and density will be dominated by a state of
quasi-free quarks and gluons referred to as the Quark-Qluon Plasma (QGP).
Experimental signals for the onset of the QGP creation (the onset of the
deconfinement) have been predicted within the statistical model for the early
stage of nucleus-nucleus collisions. In this model the existence of two
different phases is assumed: confined mater and the QGP, as well as a first
order phase transition between them. Until recently, these predictions were
confirmed only by the NA49 experiment at the CERN SPS. In this report recent
results from STAR at RHIC/BNL and from ALICE at LHC/CERN, related to the onset
of deconfinement, will be compared to published results from NA49
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