The ALICE experiment is equipped with electromagnetic calorimeters of two different types: PHOS, the lead-tungstate photon spectrometer, and EMCAL, the sampling lead-scintillator calorimeter. These two detectors measure photon spectra in a wide kinematic range and allow the reconstruction of neutral mesons decaying into photons. The measurement of the inclusive spectra of neutral meson production in pp collisions will not only provide a test of perturbative QCD but also important reference data for future heavy-ion measurements. The status of the analysis of the data accumulated during the LHC proton-proton runs at collision energies of 7 TeV and 900 GeV is shown, and the feasibility to measure the pi0 and eta meson spectra in proton-proton collisions is demonstrated.
The measurement of light vector meson production (ρ, ω, ϕ) in pp collisions provides insight into soft Quantum Chromodynamics (QCD) processes in the LHC energy range. Calculations in this regime are based on QCD inspired phenomenological models that must be tuned to the data. Moreover, light vector meson production provides a reference for high-energy heavy-ion collisions. A measurement of the ϕand ωdifferential cross sections as performed by the ALICE experiment in pp collisions at 7 TeV and of the ϕcross section in pp collisions at 2.76 TeV through their decay to muon pairs and in the rapidi…
The azimuthal correlation of D mesons with charged particles in pp collisions at $\sqrt{s}$ = 7 TeV was measured using the ALICE detector at LHC. This measurement allows us to gain insight into heavy-flavour production processes and parton shower. The results are compared with the measurement performed in p-Pb collisions. The yield of charged particles in the near-side correlation peak and the peak width measured in the two collision systems are compatible, within the uncertainties, and described by Monte Carlo simulations.
The $\textit p_{T}$-differential cross section of D mesons in the rapidity range $|y|< 0.5$ was measured in pp collisions at $\sqrt{s}$ = 2.76, 7 and 8 TeV. D mesons were reconstructed in their hadronic decay channels by means of the invariant mass analysis. The D-meson production cross sections is compared among different energies and to pQCD calculations. Also the prompt D meson are studied as a function of the multiplicity of charged articles produced in inelastic pp collisions at a centre-of-mass energy of $\sqrt{s}$ = 7 TeV. The measurements are compared with model calculations.
The purpose of the ALICE experiment at the LHC is the study of the Quark Gluon Plasma (QGP) formed in ultra-relativistic heavy-ion collisions, a state of matter in which quarks and gluons are deconfined. The properties of this state of strongly-interacting matter can be accessed through the study of light vector mesons ($ρ$, $ω$ and $ϕ$). Indeed, the strange quark content ($s\bar{s}$) of the $ϕ$ meson makes its study interesting in connection with the strangeness enhancement observed in heavy-ion collisions. Moreover, $ρ$ and $ω$ spectral function studies give information on chiral symmetry re…
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.
The ALICE collaboration at the LHC has measured the transverse momentum spectra of neutral pions via their two photon decay in pp and Pb$-$Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV over a broad transverse momentum range with different subsystems: with the electromagnetic calorimeters PHOS and EMCAL and with photon conversions in the inner material of the detectors using $e^{+}e^{-}$ pairs reconstructed with the Central Tracking System. In this report, neutral pions production is compared between pp and Pb$-$Pb collisions measured with conversion photons in terms of the nuclear modification fac…
We present the preliminary pt differential cross section in pp collisions of the D+s meson measured in the mid-rapidity region of ALICE with an integrated luminosity of 4.8 nb^-1. The ratios between all the D meson preliminary pt differential cross sections measured in the ALICE experiment (D+s,D0,D+,D*+) are also presented and compared with the results of other experiments.
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 $\sqrt{s_{\mathrm{NN}}} = 5.02~\mathrm{TeV}$.
The production of heavy-flavour hadrons in high-energy hadronic collisions is a unique source of information on various aspects of quantum chromodynamics (QCD). Production of heavy-flavour hadrons in proton--proton collisions allows the test of perturbative QCD models, while the comparison of mesons and baryons with heavy-flavour quarks can differentiate between fragmentation scenarios. Multiplicity-dependent measurements allow for the understanding of semi-hard vacuum QCD effects, as well as to study the coalescence mechanisms of heavy-flavour quarks with light and strange quarks. Recent resu…
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.
Among the probes used to investigate the properties of the Quark-Gluon Plasma, the measurement of the energy loss of high-energy partons can be used to put constraints on energy-loss models and to ultimately access medium characteristics, such as the energy density or the temperature. The study of two-particle correlations allows us to obtain very different constraints compared to the nuclear modification factor. In particular, the correlation of charged hadrons with high energy $π^{0}$ or direct photons is believed to give a measurement of the parton energy loss and insights into the medium-i…
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.
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…
The ALICE experiment, at the Large Hadron Collider located at CERN, is designed to investigate the physics of strongly interacting matter at very high energy densities. We present an analysis strategy of reconstructing open charm mesons with ALICE via the hadronic decay of D0 and D* mesons. Heavy flavours, produced at the The Large Hadron Collider, are excellent tools to investigate the properties of the QCD medium produced in heavy-ion collisions. Baseline measurements of heavy flavour production mechanisms in pp collisions are necessary in order to understand the production in the medium as …
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…
Vector meson photoproduction at high energies has attracted increased interest in recent years due to the unique kinematical ranges offered by the LHC experiments. The ALICE and LHCb collaborations have provided measurements of vector meson photoproduction on nuclear and proton targets, i.e. off p, Pb and Xe targets. The large data sets available from LHC Run 2 allow for more differential measurements. The ALICE and LHCb collaborations have recently provided measurements of coherent \jpsi in \PbPb ultra-peripheral collisions (UPC). In addition, the former also reports the first measurement of …
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 …
The study particle azimuthal anisotropy in heavy-ion collisions provides insight on the collective hydrodynamic expansion of the system and on its equation of state. The measurement of the elliptic flow, $v_2$, of D mesons compared to that of light hadrons is expected to be sensitive to the degree of thermalization of charm quarks within the quark-gluon plasma. The first measurement of D$^0$ meson $v_2$ with the ALICE detector at the LHC will be presented. The preliminary results obtained with the first Pb-Pb run at LHC show a hint of non-zero $v_2$ in $2<p_{\rm t} <5 $ GeV/$c$.
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.
We present the results for direct photon and neutral pion production obtained from proton-proton and lead-lead collisions in the ALICE experiment. Measurement of neutral pions in pp collisions allows to test the validity of QCD-inspired models. The study of neutral pion yields in Pb-Pb collisions permits to study the medium-induced suppression relative to the pp case. The yield of direct photons is compared to perturbative QCD calculations. In the case of central Pb-Pb collisions the observed excess of photons below 4 GeV/c is used to find the effective temperature of the matter.
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…
The measurement of heavy-flavour production in pp collisions at the LHC allows to study the production mechanisms and to test perturbative Quantum Chromodynamics (pQCD) in a new energy domain. Further it provides important reference data for investigations of the medium effects in Pb-Pb collisions, where charm and beauty production measurements are regarded as a unique probe for parton-medium interaction dynamics. We present preliminary results of open heavy-flavour production measurements with ALICE using hadronic D meson decays as well as semi-leptonic decays of D and B mesons and compare th…
Differential invariant cross sections of light neutral mesons in p-Pb collisions at $\sqrt{s_{\text{NN}}}$ = 8.16 TeV and in pp collisions at $\sqrt{s}$ = 8 TeV have been measured up to very high transverse momentum ($p_{\text{T}}$). By combining independent reconstruction techniques available in ALICE using the EMCal and PHOS calorimeters as well as the central barrel tracking detectors, the combined spectra cover almost two orders of magnitude in $p_{\rm T}$ for the $π^{0}$ meson. The nuclear modification factor $R_{\text{pPb}}$ has been measured for the $π^{0}$ and $η$ mesons and is found t…
The latest results on charm-tagged jets and open-charm production obtained with \mbox{ALICE} at the LHC are presented. The baryon-to-meson ratios for $\mathrm{Λ^+_c}$, $\mathrm{Σ^{0,+,++}_c}$ and $\mathrm{Ξ^{0,+}_c}$ measured in pp collisions at $\sqrt{s}=13\ \mathrm{TeV}$ are discussed. The measurements of the jet-momentum fraction carried by the $\mathrm{D^0}$ meson and $\mathrm{Λ^+_c}$ baryon in pp collisions at $\sqrt{s}=13\ \mathrm{TeV}$ are reported, and the number of leading-parton splittings $n_{SD}$ for $\mathrm{D^0}$-tagged and inclusive jets in pp collisions at $\sqrt{s}=13\ \mathrm…
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-…
The measurement of the heavy-flavour production cross sections in pp collisions at the LHC will allow to test perturbative QCD calculations in a new energy domain. Moreover, within the physics program of the ALICE experiment, it will provide the reference for the study of medium effects in Pb-Pb collisions, where heavy quarks are regarded as sensitive probes of parton-medium interaction dynamics. We present the status and first preliminary results of charm and beauty production measurements with the ALICE experiment, using hadronic D meson decays and semi-leptonic D and B meson decays, includi…
Central exclusive production at hadron colliders is characterised by the hadronic state produced at or close to midrapidity, and by the two forward scattered protons, or remnants thereof. No particles are produced between the midrapidity system and the forward going beam particles, and such events can hence be identified experimentally by a double-gap topology. At LHC energies, central exclusive production in proton-proton collisions is dominated by pomeron-pomeron fusion. The models to describe such reactions are reviewed, and the ongoing efforts in the ALICE Collaboration to analyse double-g…
The ALICE experiment has measured charm and beauty production in pp and Pb-Pb collisions at sqrt(s) = 2.76 and 7 TeV and sqrt(sNN) = 2.76 TeV, respectively, via the exclusive reconstruction of hadronic D meson decays and semi-leptonic D and B meson decays. In this contribution, recent results on the nuclear modification factor for open charmed mesons and heavy-flavour decay electrons at central rapidity and muons at forward rapidity are presented and discussed.
We have studied the azimuthal correlations between $\rm D^0$, $\rm D^+$ and $\rm D^{*+}$ mesons and charged particles in pp collisions at $\sqrt{s}=7~\mathrm{TeV}$ and p-Pb collisions at ${\sqrt{s_{\scriptscriptstyle \rm NN}}}=5.02~\mathrm{TeV}$ at the Large Hadron Collider. D mesons were reconstructed from their hadronic decays in the central rapidity region and in the transverse-momentum range 3 $\le p_{T} \le$ 16 $\mathrm{GeV}/c$, and they were correlated to charged particles reconstructed in the pseudo-rapidity range $|η| < 0.8$. A comparative study of the pp results with Monte Carlo Pythi…
The measurement of D meson production provides key tests for parton energy-loss models, which predict that charm quarks should experience less in-medium energy loss than light quarks and gluons. The ALICE experiment has measured the production of prompt D^(0), D^(+) and D^(*+) mesons 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 their hadronic decay. The pT-differential production yields in the range 2 < pT < 16 GeV/c at central rapidity, |y| < 0.5, were used to calculate the nuclear modificatio…
The ALICE experiment at the LHC was taking data in proton-proton collisions at the center-of-mass energy of 7 TeV starting from March till the end of October 2010. First heavy-ion collisions were delivered during November 2010. Among other particles, charmed and beauty mesons can be reconstructed by the ALICE apparatus. Open heavy flavour mesons provide a powerful tool to study hot quark matter produced in high energy heavy-ion collisions because their spectra are expected to be affected by energy loss in the medium. Measuring such particles is important also in proton-proton collisions. In th…
We present results of femtoscopic analysis with K0s-K0s, Kch-Kch, p-p, pbar-pbar, p-pbar and lambda-antilambda in Pb-Pb collisions at sqrt{s_NN}=2.76 TeV and K0s-K0s in pp collisions at sqrt{s}=7 TeV registered by ALICE at the LHC. The femtoscopic radius is extracted from the one-dimensional correlation functions. The analysis reveals that the emission source sizes of pions, kaons and protons measured in heavy-ion collisions exhibit approximate transverse mass scaling which is consistent with hydrodynamic collectivity prediction. Furthermore, baryon-antibaryon correlations are investigated to …
The strong electromagnetic fields surrounding the Pb-ions accelerated at the CERN Large Hadron Collider (LHC) allow two-photon and photonuclear interactions to be studied in a so far unexplored kinematic regime. Exclusive photoproduction of vector mesons can be studied in ultra-peripheral collisions, where the impact parameters are larger than the sum of the nuclear radii and hadronic interactions are strongly suppressed. During the heavy-ion runs at the LHC in 2010 and 2011, the ALICE collaboration used special triggers to select ultra-peripheral collisions. These triggers were based on the M…
We present the measurements related to the spin alignment of $\mathrm{K^{*0}}$ and $\mathrmϕ$ vector mesons at mid-rapidity for Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV using the ALICE detector at the LHC. The second diagonal spin density matrix element ($ρ_{00}$) is measured from the angular distribution of the decay daughters of the vector meson in the decay rest frame, with respect to the event plane and the production plane. The $ρ_{00}$ values are found to be less than 1/3 at low $p_{\mathrm{T}}$ ($<$ 2 GeV/$c$) for both vector mesons. The observed deviations from 1/3 are …
The quark model has proven successful in describing the basic building blocks of strongly interacting particles in the Standard Model, where hadronic states consist of quarks and gluons. At the same time, Lattice QCD predicts the possibility of glueball candidates in the mass range \mbox{1550--1750} MeV/$c^2$, which have never been observed. The experimental search for the existence of mesons with no quark content is both interesting and challenging as the glueball is very likely to mix with surrounding quark-antiquark scalar meson states with the same quantum numbers. The large statistics dat…
The comparison of angular correlations between charmed mesons and charged hadrons produced in pp, p-Pb and Pb-Pb collisions can give insight into charm quark energy loss mechanisms in hot nuclear medium formed in heavy-ion collisions and can help to spot possible modifications of charm quark hadronization induced by the presence of the medium. The analysis of pp and p-Pb data and the comparison with predictions from pQCD calculations, besides constituting the necessary baseline for the interpretation of Pb-Pb results, can provide relevant information on charm production and fragmentation proce…
The ALICE detector is dedicated to studying the properties of hot and dense matter created in heavy-ion collisions. Among the probes used to investigate these properties are high-momentum particles, which originate in hard-scatterings occurring before the fireball creation. The fragments of hard scatterings interact with the hot and dense matter and via this interaction their spectra and azimuthal distributions are modified. This is probed by the measurement of the nuclear modification factor, where the $p_{\mathrm{T}}$ spectra obtained in Pb-Pb collisions are compared to a pp baseline. A stro…
One of the key signatures of the Quark-Gluon Plasma (QGP) is the modification of hadron transverse momentum differential cross-sections in heavy-ion collisions (HIC) as compared to proton-proton (pp) collisions. Suppression of hadron production at high transverse momenta ($p_{\rm T}$) in HIC has been explained by the energy loss of the partons produced in the hard scattering processes which traverse the deconfined quantum chromodynamic (QCD) matter. The dependence of the observed suppression on the $p_{\rm T}$ of the measured hadron towards higher $p_{\rm T}$ is an important input for the theo…
The intense photon fluxes of relativistic nuclei provide a possibility to study photonuclear and two-photon interactions in ultra-peripheral collisions (UPC) where the nuclei do not overlap and no strong nuclear interactions occur. The study of such collisions provides information about the initial state of nuclei. First ALICE results from the LHC Run 2 are presented for forward exclusive \jpsi production in UPC, which is sensitive to the gluon distribution in nuclei. The increased statistics and the higher collision energy allows for a more detailed study at lower values of Bjorken-$x$. The a…
Heavy quarks (charm and beauty) are produced in hard-scattering processes and the study of their production in proton--proton (pp) collisions is an important test for calculations based on perturbative Quantum Chromodynamics (pQCD). Heavy-flavor production as a function of charged-particle multiplicity provides insight into the processes occurring at the partonic level and the interplay between the hard and soft particle production mechanisms in pp collisions. In this contribution, measurements of open heavy-flavor production as a function of multiplicity, via the study of the $\mathrm{D}$-mes…
The production of open heavy-flavour particles was studied in p-Pb collisions at $\sqrt{s_\mathrm{NN}}=5.02$ TeV using the ALICE detector. Three separate observables were used: the hadronic decays of D mesons at mid-rapidity, and semileptonic decays of heavy-flavour hadrons to electrons and muons at mid-rapidity and forward rapidity, respectively. The most recent ALICE measurements of the nuclear modification factor, $R_\mathrm{pPb}$, of open charm and beauty are reported, along with the centrality and multiplicity dependence of D-meson production in p-Pb collisions.
The ALICE Collaboration studies the production of J/psi meson in pp collisions at the center-of-mass energies of 2.76 and 7 TeV at mid- and forward-rapidity. Inclusive production cross-sections are presented as a function of the collision energy, rapidity and transverse-momentum. The J/psi polarization measurements in the helicity and Collins-Soper frames are discussed. A novel result on the correlation between the collision charged particle multiplicity and J/psi yield is also shown.
The production of heavy quarks in pp collisions at the LHC energies provides a reliable test of perturbative QCD calculations. Comparisons of pp and $\pPb$ measurements of their hadronization products allow us to investigate how cold nuclear matter effects affect the heavy-quark production. We present ALICE measurements of azimuthal correlations of prompt D mesons with charged hadrons in pp collisions at $\s$ = 7 TeV and $\pPb$ collisions at $\sNN$ = 5.02 TeV. We also show the per-event D-meson yields as a function of the charged-particle multiplicity in pp collisions at $\s$ = 7 TeV.
The production of charm-hadrons at midrapidity in pp collisions at $\sqrt{s}$ = 5.02 and 13 TeV was recently measured by the ALICE Collaboration. The results show that the baryon-to-meson yield ratios differ from predictions where the hadronisation has been tuned to measurements obtained in $\rm e^{+}e^{-}$ and ep collisions for different charm-baryon species. These observations suggest that the charm fragmentation fractions are not universal and that the baryon-to-meson ratio depends on the collision systems. The results are compared to the predictions from Monte Carlo event generators and th…
The ALICE experiment at the CERN LHC has conducted first systematic studies of heavy-flavour hadron production in pp collisions at sqrt(s) = 7 TeV and in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV. In pp collisions the differential production cross sections of D mesons at mid-rapidity, as well as the cross sections for electrons and muons from semileptonic heavy-flavour hadron decays at mid- and forward-rapidity, respectively, have been measured. These data provide a crucial testing ground for perturbative QCD calculations in the new LHC energy regime. In Pb-Pb collisions, the nuclear modificat…
A review of recent experimental measurements of the lifetime and mixing parameters of neutral D and B hadrons is presented. In particular, focus is given to measurements of D mixing and the Lambda_B lifetime.
We present the measurements related to global polarization of $Λ$ hyperons and spin alignment of $\mathrm{K^{*0}}~$ vector mesons at mid-rapidity for Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}~$= 2.76 TeV using the ALICE detector at the LHC. The global polarization measurements are carried out with respect to the first order event plane while the spin alignment measurements are carried out with respect to the production plane. No global polarization signal for $Λ$ is observed for 5-15\% and 15-50\% central Pb-Pb collisions. The spin density matrix element $ρ_{00}$ is found to have values slig…
Two-particle correlation triggered by high-\pt{} particles allows us to study hard scattering phenomena when full jet reconstruction is challenging. An analysis of the first ALICE pp data where charged and neutral particles isolated or not are used as trigger particles is presented. The two-particle correlation between the trigger ($t$) and the associate ($a$) particles is studied as a function of the imbalance parameter \xe=-$\vec{p}_{T_{a}} \cdot \vec{p}_{T_{t}}/\mid \vec{p}_{T_{t}}\mid ^{2}$ and interpreted in terms of jet fragmentation function.
We report on the first measurement of J/Psi production as a function of charged particle pseudo-rapidity density dN_ch/d_eta in pp collisions at sqrt{s} = 7 TeV with the ALICE experiment at the LHC. J/Psi mesons are detected down to p_T = 0 via their decays into e+e- pairs at mid-rapidity (|y| < 0.9) and into mu+mu- pairs at forward rapidity (2.5<y<4). dN_ch/d_eta is measured within |eta| < 1. We compare results in the two different J/Psi rapidity ranges. Preliminary PYTHIA simulations are also presented.
Heavy quarks produced in pp and heavy ion collisions are studied using heavy-flavour decay electrons and heavy-flavour mesons. Detailed understanding of the production processes and fragmentation of heavy quarks can be obtained by studying the azimuthal angular correlation of heavy-flavour hadrons. The azimuthal angular correlations of heavy-flavour mesons and charged hadrons can be used to disentangle charm and beauty-hadrons in pp collisions. In this contribution the fraction of electrons from beauty-hadron decays in the heavy-flavour decay electron yield is shown as well as the beauty produ…
Photoproduction of $ρ^0$ mesons in ultra-peripheral Pb+Pb collisions has been studied by the ALICE Collaboration at the CERN LHC. The strong photon flux associated with relativistic charged nuclei leads to a very large cross section for exclusive photoproduction of $ρ^0$ meson in interactions of the type $Pb + Pb \rightarrow Pb + Pb + ρ^0$. For a $ρ^0$ produced at mid-rapidity at the LHC, the photon-nucleus center of mass energy is higher than in any previous experiment. The ALICE detector is a general purpose detector dedicated to study heavy--ion collisions. ALICE has excellent performance i…
