Heavy quarks are a powerful probe for investigating the properties of the Quark-Gluon Plasma created in heavy-ion collisions, since they are produced in initial hard scattering processes and experience all the stages of the medium evolution. ALICE has measured the production of $\mathrm{D}^0$, $\mathrm{D}^+$, $\mathrm{D}^{*+}$, and $\mathrm{D}_{\mathrm{s}}^+$ mesons at central rapidity in their hadronic decay channels in various collision systems and energies. We present recent results for D-meson production measured by the ALICE Collaboration in pp collisions at $\sqrt{s}=7$ and 2.76 TeV, Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}=2.76$ TeV and p-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV.
The ALICE experiment at LHC is mainly dedicated to heavy-ion physics. An overview of its performances, some predictions related to its first measurements and QGP observable measurements will be given.
The ALICE experiment at the Large Hadron Collider LHC is presented, and an overview of its physics program is given. A few specific observables are discussed in order to illustrate the physics potential of ALICE.
The ALICE experiment at the Large Hadron Collider (LHC) at CERN consists of a central barrel, a muon spectrometer and additional detectors for trigger and event classification purposes. The low transverse momentum threshold of the central barrel gives ALICE a unique opportunity to study the low mass sector of central exclusive production at the LHC.
The measurement of D-meson production in heavy-ion collisions at LHC energy provides insights into the mechanisms of interaction of charm quarks in the hot and dense medium formed in these collisions. ALICE results on the D-meson nuclear modification factor and azimuthal anisotropy in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV are presented.
Measurements of charm and beauty production in pp collisions, using the ALICE detector system, at LHC energies ($\sqrt{s} = 2.76$ and 7.0 TeV) can test perturbative QCD down to very low Björken-x. They are also critical as a reference to ALICE's heavy ion program. The ALICE detector system allows measurements not covered by the other LHC experiments in addition to covering complementary regions. A description of the ALICE detector system, in relation to ATLAS and CMS, are presented. Results from both leptonic and hadronic decay channels will be shown along with comparisons to other measurement…
We present here recent open heavy-flavour results from the ALICE experiment, including measurements of D-meson, $\mathrm{Λ_{c}^{+}}$ baryon and $\mathrm{Ξ_c^0}$ baryon production in pp collisions at $\sqrt{s} = 7~\mathrm{TeV}$ and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02~\mathrm{TeV}$.
After close to 20 years of preparation, the dedicated heavy ion experiment ALICE took first data with proton collisions at the LHC starting in November 2009 and first Pb-Pb data in November 2010. This article summarizes initial operation and performance of ALICE as well as first results from both pp and Pb-Pb collisions.
In ALICE, open heavy-flavour production is studied through the measurements of the leptons (electrons and muons) from heavy-flavour hadron decays at central and forward rapidity and via the reconstruction of D-meson hadronic decays at mid-rapidity. An overview of the open heavy-flavour production with ALICE in pp ($\sqrt{s}$ = 2.76 TeV and 7 TeV), p--Pb ($\sqrt {s_{\rm NN}}$ = 5.02 TeV) and Pb--Pb ($\sqrt {s_{\rm NN}}$ = 2.76 TeV) collisions will be presented. We will discuss the production cross sections, modifications of the transverse momentum distributions, azimuthal anisotropic emissions …
Results on open heavy-flavour production in Pb-Pb collisions at sqrt{s_NN} = 2.76 TeV measured with ALICE at the LHC are presented. The nuclear modification factors, extracted in three different channels, show a strong suppression in central collisions. The measured D-meson azimuthal anisotropy indicates a non-zero v2, which is similar to the one of charged hadrons.
The pseudorapidity density and multiplicity distributions of charged particles have been the first measurements carried out with the ALICE detector at the LHC. After an introduction on the experiment and some details on the subdetectors relevant for these measurements, results from minimum bias proton-proton collisions at 0.9, 2.36 and 7 TeV are presented. Comparisons with other measurements and model predictions are also discussed.
The ALICE detector is well suited to measure heavy-flavour (charm and beauty) production via hadronic and semi-leptonic decay channels of heavy-flavour particles. Here an overview of heavy-flavour measurements made with the ALICE detector during Run 1 in pp and p--Pb collisions is presented and discussed.
The ALICE experiment at the Large Hadron Collider (LHC) at CERN consists of a central barrel, a muon spectrometer and of additional detectors for trigger and event classification purposes. The low transverse momentum threshold of the central barrel gives ALICE a unique opportunity to study the low mass sector of central production at the LHC. First analysis results of meson production in double gap events in proton-proton collisions at $\sqrt{s}$ = 7 TeV and in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV are presented.
After 20 years of preparation, the dedicated heavy ion experiment ALICE took first data at the CERN LHC accelerator with proton collisions at the end of 2009 and with lead beams at the end of 2010. This article will give a brief overview of the main results presented at the Quark Matter 2011 conference.
Silicon Drift Detectors (SDD) equip the two central layers of the Inner Tracking System of the ALICE experiment at the LHC. Main results of systematic studies of detector performance including noise, gain, drift speed and charge collection measurements will be reported
Reference cross sections have been measured with the ALICE detector in both pp and Pb-Pb collisions, in dedicated luminosity calibration experiments (van der Meer scans) at the LHC. The results and their uncertainties are discussed, together with a few selected applications.
ALICE is the LHC experiment dedicated to the study of Heavy-Ion collisions. Many observables related to the properties of the medium created in such collisions rely on the excellent capabilities of the detector in terms of Particle Identification (PID) of particles. In the following, the various PID techniques used for the different ALICE analyses will be described. Focus will be given to the detectors' performance, and selected results will be presented on pp data collected at sqrt(s) = 7 TeV and PbPb collisions at sqrt(s_NN) = 2.76 TeV.
The ALICE detector at the LHC recorded first Pb-Pb collisions at 2.76 TeV in November and December of 2010. We report on the measurements of anisotropic flow for charged and identified particles. From the comparison with measurements at lower energies and with model predictions we find that the system created at these collision energies is described well by hydrodynamical model calculations and behaves like an almost perfect fluid.
We report on the pseudo-rapidity dependence of the charged particle anisotropic flow in Pb-Pb collisions at 2.76 TeV. The measurement is done over a wide range of pseudo-rapidity, |η|<5 using the forward detectors of ALICE at the LHC. Results are obtained from two- and multi-particle correlation techniques with the latter being less sensitive to non-flow effects. Elliptic flow longitudinal scaling, comparison with RHIC data and AMPT model calculations for the LHC are discussed.
The measurements of open heavy-flavours, i.e. D mesons at central rapidity and leptons from charm and beauty decays at central and forward rapidity was studied in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV using the ALICE detector. The results are presented and compared to model predictions including cold nuclear matter effects.
The measurement of the prompt charm mesons D0, D+, D*+, and their antiparticles, in PbPb collisions at the LHC, at a centre-of-mass energy sqrt{s_{NN}}=2.76 TeV, with the ALICE detector, using 2010 data, is presented. The RAA of the three meson species show a suppression of a factor 3-4, for transverse momenta larger than 5 GeV/c, in the 20% most central collisions. The suppression is reduced for peripheral collisions. The results are compared with those of charged particles, charged pions, and non-prompt Jpsi, and also with theoretical calculations.
ALICE at the LHC has a unique potential to study proton-proton collisions with the goal to probe Quantum ChromoDynamics (QCD). The apparatus was designed to reconstruct particles over a large range in transverse momentum and rapidity. In particular, quarkonia are very interesting probes of QCD, because their production mechanisms are governed by both perturbative and non-perturbative QCD processes. In ALICE, quarkonia are reconstructed via their dilepton decay channel down to zero transverse momentum. This contribution gives a short overview of quarkonium production results in proton-proton co…
In this paper, an overview of recent $\mathrm D^{0}$, $\mathrm D^{+}$ and $\mathrm D^{*+}$ measurements, performed by ALICE in proton--proton collisions at $\sqrt{s}~=~2.76$, 5, 7, 8 and 13 TeV, is reported. The minimum-bias production cross sections, as well as their energy and species dependences, are compared to perturbative QCD calculations. The evolution of the D-meson yields with the event multiplicity is compared to phenomenological models.
Hadronic resonances $\mathrm{K}^{*}(892)^{0}$, $ϕ$(1020) and $Σ(1385)^{\pm}$ have been measured by the ALICE experiment in pp collisions at $\sqrt{s}=7$ TeV and in Pb-Pb collisions at $\sqrt{s_{_\mathrm{NN}}}=2.76$ TeV. Transverse momentum spectra, particle ratios, nuclear modification factor and comparison with model predictions are discussed. In addition, ALICE results are compared with data obtained at RHIC energy.
The properties of the hot and dense QCD medium formed in ultra-relativistic heavy ion collisions, as well as the mechanism of in-medium partonic energy loss, can be accessed via the study of the D mesons nuclear modification factor. The ALICE experiment has measured D meson production in pp and Pb-Pb collisions at the LHC at $\sqrt{s}$ =7 and 2.76 TeV and at $\sqrt{s_{NN}}$ = 2.76 TeV, respectively, via the exclusive reconstruction of hadronic decay channels. D mesons are selected by exploiting the high-resolution tracking performance and the hadron identification capabilities of the ALICE det…
ALICE is the heavy-ion experiment at the CERN Large Hadron Collider. The experiment continuously took data during the first physics campaign of the machine from fall 2009 until early 2013, using proton and lead-ion beams. In this paper we describe the running environment and the data handling procedures, and discuss the performance of the ALICE detectors and analysis methods for various physics observables.
Probes for the small-x parton densities and predicted effects of gluon saturation are discussed. At very low x and intermediate Q, only results on hadronic observables at the LHC are available, which do not provide unambiguous information. It is shown that the measurement of direct photons at forward rapidity at the LHC is particularly promising to provide a unique signal. We further discuss the possibilities to perform such measurements with a detector upgrade in the ALICE experiment and present the R&D activities ongoing.
These proceedings describe the charged-particle pseudorapidity densities and multiplicity distributions measured by the ALICE detector in pp collisions at $\sqrt{s} = 0.9$ and 7 TeV in specific phase space regions. The pseudorapidity range $|η| < 0.8$, together with $p_{\rm T}$ cuts at 0.15, 0.5 and 1 GeV/$c$ is considered. The classes of events considered are those having at least one charged particle in the kinematical ranges just described. The results obtained by ALICE are compared to Monte Carlo predictions.
We present measurements of charged jet cross sections and jet shape observables in leading jet in proton-proton (pp) collisions at sqrt(s) = 2.76 TeV with the ALICE detector at LHC. Jets are reconstructed at the midrapidity from charged particle using sequential recombination anti-kT jet finding algorithm for various R values. The results are compared to measurements from HERWIG, PHOJET and different tunes of PYTHIA6 and earlier measurements at 7 TeV.
The ALICE experiment is equipped with a wide range of detectors providing excellent tracking and particle identification in the central region, as well as forward detectors with extended pseudorapidity coverage, which are well suited for studying diffractive processes. Cross section measurements of single and double diffractive processes performed by ALICE in pp collisions at $\sqrt{s}=0.9,~2.76,~7$~TeV will be reported. Currently, ALICE is studying double-gap events in pp collisions at $\sqrt{s}=7$~TeV, which give an insight into the central diffraction processes: current status and future pe…
Strange quark and particle production is studied at the LHC with unprecedented high beam energies in both heavy-ion and proton-proton collisions: on the one hand, strangeness is used for investigating chemical equilibration and bulk properties; on the other hand, strange particles contribute to probe different kinematical domains, from the one where collective phenomena are at play up to the region dominated by pQCD-calculable processes. We highlight the suitability of the ALICE experiment for this topic, presenting our latest measurements and comparing them to models.
This document describes the plans of the ALICE Collaboration for a major upgrade of its detector, referred to as ALICE 3, which is proposed for physics data-taking in the LHC Run 5 and beyond. ALICE 3 will enable an extensive programme to fully exploit the LHC for the study of the properties of strongly interacting matter with high-energy nuclear collisions. The proposed detector layout, based on advanced silicon sensors, features superb pointing resolution, excellent tracking and particle identification over a large acceptance and high readout-rate capabilities. This document discusses the pr…
We report on the studies of two-particle angular correlations measured in proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV recorded by ALICE at the LHC. Two-particle correlations in relative azimuth (Δϕ) and pseudorapidity (Δη) are expected to exhibit several structures which arise from different physics mechanisms and allow us to study the wide landscape of correlations. The results include the dependence of the correlation function on the event multiplicity, the charge combination and species (pions, kaons or protons) of particles in the pair.
Long-range correlations between particles separated by a pseudorapidity gap are a powerful tool to explore the initial stages and evolution of the medium created in hadron-hadron collisions. An overview of the long-range correlations measured by the ALICE detector in pp, p-Pb and Pb-Pb will be presented. This includes analyses of forward-backward, two- and multi-particle correlations with the use of the central barrel and forward detectors.
In November 2010 the ALICE experiment at CERN has collected the first Pb--Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV produced by the LHC. A first characterization of the hot and dense state of matter produced in this new energy domain became available shortly after the run. In this paper we present the results on charged-particle multiplicity, Bose-Einstein correlations, elliptic flow and their dependence on the collision centrality. Results from first measurements of strange and identified particle production and suppression of high-momentum hadrons with respect to $pp$ collisions are also r…
The excellent capabilities of the ALICE experiment for particle identification allow to measure the identified hadron production in a wide range of transverse momentum. In this work we present some results on identified particle spectra, strange particle production and particle contents measured in pp collisions at \sqrt{s} = 0.9, 2.76 and 7 TeV. The results are compared with Monte Carlo event generators predictions.
Two-particle azimuthal correlations of electrons from heavy-flavour hadron decays with charged particles can give insight into the properties of heavy-quark production and hadronization into heavy-flavour jets.\\ In this contribution, the ALICE results measured in pp collisions at 5.02 TeV, collected in the LHC Run 2, are presented. The yields of charged particles in the near and away-side correlation peaks and the peak width are compared with PYTHIA calculations.
Invariant cross sections for neutral pions and eta mesons in pp collisions at sqrt(s) = 0.9, 2.76, and 7 TeV were measured by the ALICE detector at the Large Hadron Collider. Next-to-leading order (NLO) perturbative QCD calculations describe the pi0 and eta spectra at 0.9 TeV, but overestimate the measured cross sections at 2.76 TeV and 7 TeV. The measured eta/pi0 ratio is consistent with mT scaling at 2.76 TeV. At 7 TeV indications for a violation of mT scaling were found.
Heavy quarks are effective probes of the properties of the QGP created in ultra-relativistic heavy-ion collisions. The ALICE Collaboration measured the non-strange D-meson production in Pb--Pb collisions at $\sqrt{s_{\rm NN\,}}=5.02$ TeV. The in-medium energy loss can be studied via the nuclear modification factor measurement. The measurement of the D-meson elliptic flow, $v_2$, allows us to investigate the participation of the heavy quarks in the collective expansion of the system at low momentum and their possible thermalization in the medium. Furthermore, the Event-Shape Engineering techniq…
In this manuscript, results of a component-level analysis with Monte Carlo simulations are presented, that aid the interpretation of recent ALICE results on the azimuthal correlation distribution of prompt D mesons with charged hadrons in pp and p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. Parton-level contributions and fragmentation properties are evaluated. Charm and beauty contributions are compared in order to identify the observables that serve as sensitive probes of the production and hadronization of heavy quarks.
This article documents the main design choices and the close to 20 years of preparation, detector R&D, construction and installation of ALICE, the dedicated heavy ion experiment at the CERN LHC accelerator.
We report the recent measurements of the inclusive J/ψ production in pp collisions at \sqrt{s} = 2.76 TeV, in pp collisions at \sqrt{s} = 7 TeV and in Pb-Pb collisions at \sqrt{s_{NN}} = 2.76 TeV with the ALICE detector at the LHC. The J/ψ mesons are detected down to pT = 0 GeV/c via their di-muon decay channel at forward rapidity (2.5 < y < 4) and via their di-electron decay channel at mid-rapidity (|y| < 0.9). A special emphasis is put on the nuclear modification factor which is compared to the predictions of current J/ψ production models.
ALICE (A Large Ion Collider Experiment) is one of the seven experiments at the the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland. ALICE is especially designed for heavy-ion collisions but it also operates a rich proton-proton (pp) program. ALICE has collected pp collision data at $\sqrt{s}=$ 0.9, 2.36, 2.76, and 7 TeV and lead-lead (Pb--Pb) collision data at $\sqrt{s_{\mathrm{NN}}}=$2.76 TeV. Here, we report minimum bias measurements obtained until the end of 2010: the results include measurements of charged-particle pseudorapidity, multiplicity and transverse momentum distributions…
Studying p-Pb collisions at LHC energies allows a quantitative evaluation of the cold nuclear matter (CNM) effects. Event activity dependence of the J/ψ production is under intense studies both theoretically and experimentally and is expected to provide important insights on the influence of CNM. This paper presents the first results on event activity dependence of the inclusive J/ψ production at backward (-4.46 < $y_{cms}$ < -2.96) and forward (2.03 < $y_{cms}$ < 3.53) rapidity in ALICE for p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV.
We present recent results on short-lived hadronic resonances obtained by the ALICE experiment in pp, p-Pb and Pb-Pb collisions at LHC energies, including the most recent measurements of $Λ(1520)$ and $Ξ(1530)^{0}$ resonances.
Open heavy-flavour hadrons are a powerful tool to investigate the properties of the high-density medium created in heavy-ion collisions at high energies as they come from the hadronization of heavy quarks. The latter are created in the early stage of the interaction and experience the whole collision history. Heavy quarks in-medium energy loss can be investigated by comparing the heavy-flavour production cross sections in p-p and nucleus-nucleus collisions. In addition, initial spatial anisotropy of the fireball is converted into momentum anysotropy of final state particles, in particular the …
ALICE is the experiment at the LHC collider at CERN dedicated to heavy ion physics. In this report, the ALICE detector will be presented, together with its expected performance as far as some selected physics topics are concerned.
We present the latest results on the ALICE performance for heavy-quark production and quenching measurements, focusing in particular on charm particles.
In this manuscript, various beauty production measurements using the ALICE detector will be presented. We will show new measurements of non-prompt D$^0$ mesons in pp collisions at $\sqrt{s} = 5.02$ TeV and beauty-tagged jet production in p--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV. The $R_{\mathrm{AA}}$ of beauty-hadron decay electrons in central Pb--Pb collisions and the $v_{2}$ of beauty-hadron decay electrons in semi-central Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV will also be discussed.
We present recent results on short-lived hadronic resonances obtained by the ALICE experiment at LHC energies. Results include system-size and collision-energy evolution of transverse momentum spectra, yields and ratios of resonance yields to those of longer lived particles, and nuclear modification factors. The results are compared with model predictions and measurements at lower energies.
We present the measurements of D0, D+, D*+ meson v_2 as well as D0 R_{AA} in different directions with respect to the estimated reaction plane in Pb-Pb collisions at sqrt(s_{NN)) = 2.76 TeV with the ALICE detector at the LHC.
The ALICE experiment has measured the D meson production in pp and Pb-Pb collisions at the LHC at {\surd}s = 7 and 2.76 TeV and {\surd}sNN = 2.76 TeV respectively, via the exclusive reconstruction of hadronic decay channels. The analyses of the D0{\to}K-pi+ and D+{\to}K-pi+pi+ channels will be described and the preliminary results for the D0 and D+ nuclear modification factor will be presented.
A study of azimuthal correlations between D$^0$, D$^+$, and D$^{*+}$ and charged particles in pp collisions at $\sqrt{s}$ = 7 TeV and p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV is presented. D mesons were reconstructed from their hadronic decays at central rapidity ($|y| < 0.5$) in the transverse momentum range $3 \leq p_{\rm T}^{\rm D} \leq 16$ GeV/$c$ and they were correlated with charged particles reconstructed in the pseudorapidity range $|η| < 0.8$. Perspectives for the measurement in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.5 TeV after the ALICE upgrade are presented as well.
In this paper, we summarize the perspectives on quarkonia detection in the ALICE experiment at the CERN LHC, both in the dielectron and dimuon decay channels.
The ALICE Collaboration has studied the inclusive J/$ψ$ and $ψ(\mathrm{2S})$ production in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV, at the CERN LHC. The J/$ψ$ measurement is performed in the $μ^{+}μ^{-}$ and in the $e^{+}e^{-}$ decay channels, down to zero $p_{\mathrm{T}}$. The results are in fair agreement with theoretical predictions. The $ψ(\mathrm{2S})$ measurement has also been performed. In particular, a smaller $ψ(\mathrm{2S})$ nuclear modification factor, with respect to the J$/ψ$ one, has been observed.
In this work we present a summary of the most relevant results on heavy-ion and astroparticle physics in ALICE. The summary includes a brief overview of the current status on the characterization of the hot and dense QCD medium created in the heavy-ion collisions produced at the LHC, as well as the intriguing finding of collective-like phenomena in small collision systems.
We present the measurement of light neutral mesons, $π^{0}$ and $η$, in pp collisions at different center-of-mass energies obtained with the ALICE experiment at the LHC. The $π^{0}$ and $η$ mesons are measured via photons reconstructed by the electromagnetic calorimeters and the central tracking system. The invariant cross-section of $π^{0}$ and $η$ mesons are measured in a broad $p_{\rm T}$ range at $\sqrt{s} = 0.9, 2.76, 7, 5.02$ and 8 TeV. The spectra of $π^{0}$ and $η$ mesons measured in pp collisions at different collision energies show $x_{\rm T}$-scaling at high $p_{\rm T}$ and violatio…
We present the expected ALICE performance for the measurement of the p_t-differential cross section of electrons from beauty decays in central Pb-Pb collisions at the LHC.
