969 research outputs found
Multi-strange baryon elliptic flow in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV measured with the ALICE detector
We present the results on elliptic flow with multi-strange baryons produced
in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV. The analysis is performed with
the ALICE detector at LHC. Multi-strange baryons are reconstructed via their
decay topologies and the v_2 values are analyzed with the two-particle scalar
product method. The p_T differential v_2 values are compared to the VISH2+1
model calculation and to the STAR measurements at 200 GeV in Au+Au collisions.
We found that the model describes \Xi and \Omega v_2 measurements within
experimental uncertainties. The differential flow of \Xi and \Omega is similar
to the STAR measurements at 200 GeV in Au+Au collisions.Comment: Prepared for the Proceedings of the International Conference on
"Critical Point and Onset of Deconfinement - CPOD 2011", Wuhan, November
7-11, 201
K0s-K0s correlations in 7 TeV pp collisions from the ALICE experiment at the LHC
Identical neutral kaon pair correlations are measured in 7 TeV pp collisions
in the ALICE experiment. K0s-K0s correlation functions are formed in 3
multiplicity X 4 kT bins. The femtoscopic kaon source parameters Rinv and
lambda are extracted from these correlation functions by fitting a (femtoscopy)
X (PYTHIA) model to them, PYTHIA accounting for the non-flat baseline found in
pp collisions. Source parameters are obtained from a fit which includes quantum
statistics and final-state interactions of the a0/f0 resonance. K0s-K0s
correlations show a systematic increase in Rinv for increasing multiplicity bin
and decreasing Rinv for increasing kT bin as seen in pi-pi correlations in the
pp system, as well as seen in heavy-ion collisions. Also, K0s-K0s correlations
are observed to smoothly extend this pi-pi Rinv behavior for the pp system up
to about three times higher kT than the kT range measured in pi-pi
correlations.Comment: Proceedings of the Quark Matter 2011 Conference, 4 pages, 5 figure
Radiative Leptonic Decays of the charged and Mesons Including Long-Distance Contribution
In this work we study the radiative leptonic decays of , and
, including both the short-distance and
long-distance contributions. The short-distance contribution is calculated by
using the relativistic quark model, where the bound state wave function we used
is that obtained in the relativistic potential model. The long-distance
contribution is estimated by using vector meson dominance model.Comment: 8 pages, 4 figures, 3 table
Heavy Ions: Results from the Large Hadron Collider
On November 8, 2010 the Large Hadron Collider (LHC) at CERN collided first
stable beams of heavy ions (Pb on Pb) at center-of-mass energy of 2.76
TeV/nucleon. The LHC worked exceedingly well during its one month of operation
with heavy ions, delivering about 10 microbarn-inverse of data, with peak
luminosity reaching to
towards the end of the run. Three experiments, ALICE, ATLAS and CMS, recorded
their first heavy ion data, which were analyzed in a record time. The results
of the multiplicity, flow, fluctuations, and Bose-Einstein correlations
indicate that the fireball formed in nuclear collisions at the LHC is hotter,
lives longer, and expands to a larger size at freeze-out as compared to lower
energies. We give an overview of these as well as new results on quarkonia and
heavy flavour suppression, and jet energy loss.Comment: Proceedings of Lepton-Photon 2011 Conference, to be published in
Pramana, Journal of Physics. 15 page
Variation of jet quenching from RHIC to LHC and thermal suppression of QCD coupling constant
We perform a joint jet tomographic analysis of the data on the nuclear
modification factor from PHENIX at RHIC and ALICE at LHC. The
computations are performed accounting for radiative and collisional parton
energy loss with running coupling constant. Our results show that the observed
slow variation of from RHIC to LHC indicates that the QCD coupling
constant is suppressed in the quark-gluon plasma produced at LHC.Comment: 9 pages, 2 figure
First Results from Pb+Pb collisions at the LHC
At the end of 2010, the CERN Large Hadron Collider started operation with
heavy ion beams, colliding lead nuclei at a centre-of-mass energy of 2.76
TeV/nucleon and opening a new era in ultra-relativistic heavy ion physics at
energies exceeding previous accelerators by more than an order of magnitude.
This review summarizes the results from the first year of heavy ion physics at
LHC obtained by the three experiments participating in the heavy ion program,
ALICE, ATLAS, and CMS.Comment: To appear in Annual Review of Nuclear and Particle Scienc
Multi-strange particle measurements in 7 TeV proton-proton and 2.76 TeV PbPb collisions with the ALICE experiment at the LHC
The production of charged multi-strange particles is studied with the ALICE
experiment at the CERN LHC. Measurements of the central rapidity yields of
and baryons, as well as their antiparticles, are presented
as a function of transverse momentum () for inelastic pp
collisions at TeV and compared to existing measurements performed
at the same and/or at lower energies. The results are also compared to
predictions from two different tunes of the PYTHIA event generator. We find
that data significantly exceed the production rates from those models. Finally,
we present the status of the multi-strange particle production studies in Pb-Pb
at TeV performed as a function of collision centrality.Comment: 4 pages, 3 figures. Submitted to the Proceedings of QM201
Analyses of multiplicity distributions with \eta_c and Bose-Einstein correlations at LHC by means of generalized Glauber-Lachs formula
Using the negative binomial distribution (NBD) and the generalized
Glauber-Lachs (GGL) formula, we analyze the data on charged multiplicity
distributions with pseudo-rapidity cutoffs \eta_c at 0.9, 2.36, and 7 TeV by
ALICE Collaboration and at 0.2, 0.54, and 0.9 TeV by UA5 Collaboration. We
confirm that the KNO scaling holds among the multiplicity distributions with
\eta_c = 0.5 at \sqrt{s} = 0.2\sim2.36 TeV and estimate the energy dependence
of a parameter 1/k in NBD and parameters 1/k and \gamma (the ratio of the
average value of the coherent hadrons to that of the chaotic hadrons) in the
GGL formula. Using empirical formulae for the parameters 1/k and \gamma in the
GGL formula, we predict the multiplicity distributions with \eta_c = 0.5 at 7
and 14 TeV. Data on the 2nd order Bose-Einstein correlations (BEC) at 0.9 TeV
by ALICE Collaboration and 0.9 and 2.36 TeV by CMS Collaboration are also
analyzed based on the GGL formula. Prediction for the 3rd order BEC at 0.9 and
2.36 TeV are presented. Moreover, the information entropy is discussed
Measurement of J/Psi production in pp collisions at sqrt(s)=2.76 and 7 TeV with ALICE
We present results from the ALICE experiment on the inclusive J/Psi
production in pp collisions at sqrt(s)=2.76 and 7 TeV. The integrated and
differential cross sections are evaluated down to pT=0 in two rapidity ranges,
|y|<0.9 and 2.5<y<4, in the dielectron and dimuon decay channel respectively.
The measurement at sqrt(s)=2.76 TeV, the same energy as Pb-Pb collisions,
provides a crucial reference for the study of hot nuclear matter effects on
J/Psi production. The J/Psi yield in pp collisions at sqrt(s)=7 TeV has also
been studied as a function of the charged particle multiplicity and first
results are presented.Comment: 4 pages, 4 figures, parallel talk at Quark Matter 2011, Annecy,
Franc
Investigation of charm and beauty production via semileptonic decays of heavy-flavour hadrons in pp at 7 TeV and Pb--Pb at 2.76 TeV with ALICE
Electron spectra measured with ALICE at mid-rapidity are used to study the
production of hadrons carrying a charm or a beauty quark. The production cross
section of electrons from heavy-flavour hadron decays is measured in pp
collisions at =7 TeV. Electrons from the beauty decays are identified
via the displacement from the interaction vertex. From the electron spectra
measured in Pb--Pb collisions, we determine the nuclear modification factor,
which is sensitive to the heavy-quark energy loss in a hot strongly interacting
medium.Comment: Quark Matter 2011 proceeding
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