Transverse momentum spectra of $\pi^{\pm}$, $\rm K^{\pm}$ and p($\bar{\rm p}$) up to $p_{\rm T}$ = 20 GeV/$c$ at mid-rapidity in pp and Pb-Pb collisions at $\sqrt{s_{\rm NN}}=$ 2.76 TeV have been measured using the ALICE detector at the Large Hadron Collider. The proton-to-pion and the kaon-to-pion ratios both show a distinct peak at $p_{\rm T} \approx 3 GeV/c$ in central Pb-Pb collisions. Below the peak, $p_{\rm T}$ < 3 GeV/$c$, both ratios are in good agreement with hydrodynamical calculations, suggesting that the peak itself is dominantly the result of radial flow rather than anomalous hadronization processes. For $p_{\rm T}$ > 10 GeV/$c$ particle ratios in pp and Pb-Pb collisions are in agreement and the nuclear modification factors for $\pi^{\pm}$, $\rm K^{\pm}$ and $\rm p$($\bar{\rm p}$) indicate that, within the systematic and statistical uncertainties, the suppression is the same. This suggests that the chemical composition of leading particles from jets in the medium is similar to that of vacuum jets.
Invariant yields of identified pions in central and peripheral Pb-Pb collisions, together with the unscaled pp reference yields.
Invariant yields of identified kaons in central and peripheral Pb-Pb collisions, together with the unscaled pp reference yields.
Invariant yields of identified protons in central and peripheral Pb-Pb collisions, together with the unscaled pp reference yields.
The inclusive production cross sections at forward rapidity of J/$\psi$, $\psi$(2S), $\Upsilon$(1S) and $\Upsilon$(2S) are measured in pp collisions at $\sqrt{s} = 7$ TeV with the ALICE detector at the LHC. The analysis is based in a data sample corresponding to an integrated luminosity of 1.35 pb$^{-1}$. Quarkonia are reconstructed in the dimuon-decay channel and the signal yields are evaluated by fitting the $\mu^+\mu^-$ invariant mass distributions. The differential production cross sections are measured as a function of the transverse momentum $p_{\rm T}$ and rapidity $y$, over the ranges $0 < p_{\rm T} < 20$ GeV/$c$ for J/$\psi$, $0 < p_{\rm T} < 12$ GeV/$c$ for all other resonances and for $2.5 < y < 4$. The measured cross sections integrated over $p_{\rm T}$ and $y$, and assuming unpolarized quarkonia, are: $\sigma_{J/\psi} = 6.69 \pm 0.04 \pm 0.63$ $\mu$b, $\sigma_{\psi^{\prime}} = 1.13 \pm 0.07 \pm 0.14$ $\mu$b, $\sigma_{\Upsilon{\rm(1S)}} = 54.2 \pm 5.0 \pm 6.7$ nb and $\sigma_{\Upsilon{\rm (2S)}} = 18.4 \pm 3.7 \pm 2.2$ nb, where the first uncertainty is statistical and the second one is systematic. The results are compared to measurements performed by other LHC experiments and to theoretical models.
Differential production cross sections of J/psi as a function of pT.
Differential production cross sections of J/psi as a function of rapidity.
integrated production cross section of J/psi.
In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p-Pb and Pb-Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p-Pb collisions are found to be 5-15% larger than those in pp, while those in Pb-Pb are 35-55% larger than those in p-Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p-Pb as compared to pp collisions at similar multiplicity.
Mixed charge C3 and c3 in pp collisions projected against 1 of a mixed-charge pair invariant relative momentum.
Same charge C3 and c3 in pp collisions projected against Q3.
Same charge C3 and c3 in p Pb collisions projected against Q3.
The production of the prompt charmed mesons $D^0$, $D^+$ and $D^{*+}$ relative to the reaction plane was measured in Pb-Pb collisions at a centre-of-mass energy per nucleon-nucleon collision of $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the LHC. D mesons were reconstructed via their hadronic decays at central rapidity in the transverse momentum ($p_{\rm T}$) interval of 2-16 GeV/$c$. The azimuthal anisotropy is quantified in terms of the second coefficient $v_2$ in a Fourier expansion of the D meson azimuthal distribution, and in terms of the nuclear modification factor $R_{\rm AA}$, measured in the direction of the reaction plane and orthogonal to it. The $v_2$ coefficient was measured with three different methods and in three centrality classes in the interval 0-50%. A positive $v_2$ is observed in mid-central collisions (30-50% centrality class), with an mean value of $0.204_{-0.036}^{+0.099}$ (tot.unc.) in the interval $2 < p_{\rm T} < 6$ GeV/$c$, which decreases towards more central collisions (10-30% and 0-10% classes). The positive $v_2$ is also reflected in the nuclear modification factor, which shows a stronger suppression in the direction orthogonal to the reaction plane for mid-central collisions. The measurements are compared to theoretical calculations of charm quark transport and energy loss in high-density strongly-interacting matter at high temperature. The models that include substantial elastic interactions with an expanding medium provide a good description of the observed anisotropy. However, they are challenged to simultaneously describe the strong suppression of high-$p_{\rm T}$ yield of D mesons in central collisions and their azimuthal anisotropy in non-central collisions.
Prompt D^0 meson v2 as a function of pT for centrality 0-10%. The first systematic uncertainty is from the data and the second from the B feed-down.
Prompt D^0 meson v2 as a function of pT for centrality 10-30%. The first systematic uncertainty is from the data and the second from the B feed-down.
Prompt D^0 meson v2 as a function of pT for centrality 30-50%. The first systematic uncertainty is from the data and the second from the B feed-down.
The transverse momentum ($p_{\mathrm T}$) distribution of primary charged particles is measured at midrapidity in minimum-bias p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV with the ALICE detector at the LHC in the range $0.15<p_{\mathrm T}<50$ GeV/$c$. The spectra are compared to the expectation based on binary collision scaling of particle production in pp collisions, leading to a nuclear modification factor consistent with unity for $p_{\mathrm T}$ larger than 2 GeV/$c$, with a weak indication of a Cronin-like enhancement for $p_{\rm T}$ around 4 GeV/$c$. The measurement is compared to theoretical calculations and to data in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV.
Transverse momentum distributions of charged particles in minimum-bias (NSD) p-Pb collisions for different pseudorapidity ranges.
The histogram represents the reference spectrum (cross section scaled by the nuclear overlap function, T(pPb)) in inelastic pp collisions, determined in |eta(cms)| < 0.8.
The ratio of spectra in p-Pb at backward pseudorapidities to that at |eta(cms)| < 0.3.
Invariant yields of neutral pions at midrapidity in the transverse momentum range $0.6 < p_{T} < 12 GeV/c$ measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV are presented for six centrality classes. The pp reference spectrum was measured in the range $0.4 < p_{T} < 10 GeV/c$ at the same center-of-mass energy. The nuclear modification factor, $R_{\rm AA}$, shows a suppression of neutral pions in central Pb-Pb collisions by a factor of up to about $8-10$ for $5 \lesssim p_{T} \lesssim 7 GeV/c$. The presented measurements are compared with results at lower center-of-mass energies and with theoretical calculations.
Invariant differential yields of PI0 produced in inelastic pp collisions at center-of-mass energy 2.76 TeV.
Invariant differential cross section of PI0 produced in inelastic pp collisions at center-of-mass energy 2.76 TeV, the uncertainty of \sigma_{inel} of 3.9% is not included in the systematic error.
Invariant differential yields of PI0 produced in 0-5% central inelastic PbPb collisions at center-of-mass energy per nucleon 2.76 TeV.
The $p_{\rm T}$-differential production cross section of electrons from semileptonic decays of heavy-flavor hadrons has been measured at mid-rapidity in proton-proton collisions at $\sqrt{s} = 2.76$ TeV in the transverse momentum range 0.5 < $p_{\rm T}$ < 12 GeV/$c$ with the ALICE detector at the LHC. The analysis was performed using minimum bias events and events triggered by the electromagnetic calorimeter. Predictions from perturbative QCD calculations agree with the data within the theoretical and experimental uncertainties.
Double-differential cross section for the production of electrons, i.e. (electron + positron)/2, from heavy-flavour hadron decays as a function of transverse momentum at mid-rapidity. The systematic uncertainties do not include an additional normalization uncertainty of 1.9%.
The ALICE collaboration at the LHC reports measurement of the inclusive production cross section of electrons from semi-leptonic decays of beauty hadrons with rapidity $|y|<0.8$ and transverse momentum $1<p_{\mathrm{T}}<10$ GeV/$c$, in pp collisions at $\sqrt{s} = $ 2.76 TeV. Electrons not originating from semi-electronic decay of beauty hadrons are suppressed using the impact parameter of the corresponding tracks. The production cross section of beauty decay electrons is compared to the result obtained with an alternative method which uses the distribution of the azimuthal angle between heavy-flavour decay electrons and charged hadrons. Perturbative QCD calculations agree with the measured cross section within the experimental and theoretical uncertainties. The integrated visible cross section, $\sigma_{\mathrm{b} \rightarrow \mathrm{e}} = 3.47\pm0.40(\mathrm{stat})^{+1.12}_{-1.33}(\mathrm{sys})\pm0.07(\mathrm{norm}) \mu$b, was extrapolated to full phase space using Fixed Order plus Next-to-Leading Log (FONLL) predictions to obtain the total b$\bar{\mathrm{b}}$ production cross section, $\sigma_{\mathrm{b\bar{b}}} = 130\pm15.1(\mathrm{stat})^{+42.1}_{-49.8}(\mathrm{sys})^{+3.4}_{-3.1}(\mathrm{extr})\pm2.5(\mathrm{norm})\pm4.4(\mathrm{BR}) \mu$b.
Azimuthal correlation distribution between heavy-flavour decay electrons and charged hadrons, scaled by the number of electrons in minimum bias triggered events in the electron transverse momentum range 1.5-2.5 GeV/$c$.
Azimuthal correlation distribution between heavy-flavour decay electrons and charged hadrons, scaled by the number of electrons in minimum bias triggered events in the electron transverse momentum range 1.5-2.5 GeV/c.
Azimuthal correlation distribution between heavy-flavour decay electrons and charged hadrons, scaled by the number of electrons in EMCal triggered events in the electron transverse momentum range 4.5-6 GeV/$c$.
The production of the strange and double-strange baryon resonances ($\Sigma(1385)^{\pm}$, $\Xi(1530)^{0}$) has been measured at mid-rapidity ($\left | y \right |<0.5$) in proton-proton collisions at $\sqrt{s}$ = 7 TeV with the ALICE detector at the LHC. Transverse momentum spectra for inelastic collisions are compared to QCD-inspired models, which in general underpredict the data. A search for the $\phi(1860)$ pentaquark, decaying in the $\Xi\pi$ channel, has been carried out but no evidence is seen.
Inelastic baryon yields, d2N/(dydpT), per pT interval per unit rapidity for Sigma(1385)+- in INEL pp collisions at sqrts 7 TeV in |y| < 0.5.
Inelastic baryon yields, d2N/(dydpT), per pT interval per unit rapidity for Xi(1530)0 in INEL pp collisions at sqrts 7 TeV in |y| < 0.5.
Mean pT as function of the mass for particles measured with the ALICE detector in INEL pp collisions at sqrts 7 TeV in |y| < 0.5.
Event-by-event fluctuations of the mean transverse momentum of charged particles produced in pp collisions at $\sqrt{s}$ = 0.9, 2.76 and 7 TeV, and Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV are studied as a function of the charged-particle multiplicity using the ALICE detector at the LHC. Dynamical fluctuations indicative of correlated particle emission are observed in all systems. The results in pp collisions show little dependence on collision energy. The Monte Carlo event generators PYTHIA and PHOJET are in qualitative agreement with the data. Peripheral Pb-Pb data exhibit a similar multiplicity dependence as that observed in pp. In central Pb-Pb, the results deviate from this trend, featuring a significant reduction of the fluctuation strength. The results in Pb--Pb are in qualitative agreement with previous measurements in Au-Au at lower collision energies and with expectations from models that incorporate collective phenomena.
Relative fluctuation $\sqrt{C_m}/M(p_{\rm T})_m$ as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$ in pp collisions at $\sqrt{s}$ = 0.9 TeV.
Relative fluctuation $\sqrt{C_m}/M(p_{\rm T})_m$ as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$ in pp collisions at $\sqrt{s}$ = 2.76 TeV.
Relative fluctuation $\sqrt{C_m}/M(p_{\rm T})_m$ as a function of $\langle {\rm d}N_{\rm ch}/{\rm d}\eta \rangle$ in pp collisions at $\sqrt{s}$ = 7 TeV.
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