65 research outputs found
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
Centrality Dependence Of The Pseudorapidity Density Distribution For Charged Particles In Pb-pb Collisions At √snn=2.76tev
7264/Mai61062
Long-range Angular Correlations On The Near And Away Side In P-pb Collisions At √snn=5.02 Tev
7191/Mar294
KK correlations in pp collisions at TeV from the LHC ALICE experiment
Identical neutral kaon pair correlations are measured in TeV pp
collisions in the ALICE experiment. One-dimensional KK correlation
functions in terms of the invariant momentum difference of kaon pairs are
formed in two multiplicity and two transverse momentum ranges. The femtoscopic
parameters for the radius and correlation strength of the kaon source are
extracted. The ft includes quantum statistics and final-state
interactions of the a/f resonance. KK correlations show an
increase in radius for increasing multiplicity and a slight decrease in radius
for increasing transverse mass, , as seen in correlations
in the pp system and in heavy-ion collisions. Transverse mass scaling is
observed between the KK and radii. Also, the frst
observation is made of the decay of the f(1525) meson into the
KK channel in pp collisions.Comment: 17 pages, 7 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/310
Transverse Momentum Distribution and Nuclear Modification Factor of Charged Particles in p-Pb Collisions at sqrt{s_NN} = 5.02 TeV
16 pages, 3 figures; submitted to Phys. Rev. Lett ; see paper for full list of authorsThe transverse momentum (p_T) distribution of primary charged particles is measured in non single-diffractive p-Pb collisions at sqrt{s_NN} = 5.02 TeV with the ALICE detector at the LHC. The p_T spectra measured near central rapidity in the range 0.5 < p_T < 20 GeV/c exhibit a weak pseudorapidity dependence. The nuclear modification factor R_pPb is consistent with unity for p_T above 2 GeV/c. This measurement indicates that the strong suppression of hadron production at high p_T observed in Pb-Pb collisions at the LHC is not due to an initial-state effect. The measurement is compared to theoretical calculations
Pseudorapidity density of charged particles in p-Pb collisions at sqrt(sNN) = 5.02 TeV
16 pages, 2 figures, authors at page 11, submitted to PRL ; see paper for full list of authorsThe charged-particle pseudorapidity density measured over 4 units of pseudorapidity in non-single-diffractive (NSD) p-Pb collisions at a centre-of-mass energy per nucleon pair sqrt(sNN) = 5.02 TeV is presented. The average value at midrapidity is measured to be 16.81 \pm 0.71 (syst.), which corresponds to 2.14 \pm 0.17 (syst.) per participating nucleon. This is 16% lower than in NSD pp collisions interpolated to the same collision energy, and 84% higher than in d-Au collisions at sqrt(sNN) = 0.2 TeV. The measured pseudorapidity density in p-Pb collisions is compared to model predictions, and provides new constraints on the description of particle production in high-energy nuclear collisions
D meson elliptic flow in non-central Pb-Pb collisions at sqrts(s_NN) = 2.76TeV
17 pages, 3 captioned figures, authors from page 10 to page 12 ; see paper for full list of authorsAzimuthally anisotropic distributions of D0, D+ and D*+ mesons were studied in the central rapidity region (|y|<0.8) in Pb-Pb collisions at a centre-of-mass energy sqrts(s_NN) = 2.76TeV per nucleon-nucleon collision, with the ALICE detector at the LHC. The second Fourier coefficient v2 (commonly denoted elliptic flow) was measured in the centrality class 30-50% as a function of the D meson transverse momentum pt, in the range 2-16GeV/c$. The measured v2 of D mesons is comparable in magnitude to that of light-flavour hadrons. It is positive in the range 2 < pt < 6 GeV/c with 5.7 sigma significance, based on the combination of statistical and systematic uncertainties
Measurement of the inclusive differential jet cross section in pp collisions at sqrt{s} = 2.76 TeV
17 pages, 4 figures, author list from page 12; submitted to Physics Letters B ; see paper for full list of authorsThe ALICE collaboration at the CERN Large Hadron Collider reports the first measurement of the inclusive differential jet cross section at mid-rapidity in pp collisions at sqrt(s) = 2.76 TeV, with integrated luminosity of 13.6 nb^-1. Jets are measured over the transverse momentum range 20 to 125 GeV/c and are corrected to the particle level. Calculations based on Next-to-Leading Order perturbative QCD are in good agreement with the measurements. The ratio of inclusive jet cross sections for jet radii R = 0.2 and R = 0.4 is reported, and is also well reproduced by a Next-to-Leading Order perturbative QCD calculation when hadronization effects are included
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