Two-particle correlations at small relative momenta give insight into the size of the emitting source. Of particular interest is the test of hydrodynamic models which predict a universal, apparent decrease of the extent of the system with increasing transverse mass mT as a consequence of the strong radial flow in heavy-ion collisions at LHC energies. This contribution presents a study of correlations for protons and Λ particles in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV measured with ALICE. The investigated particle species expand the experimental reach in mT due to their high rest mass. Residual impurities in the samples from misidentification and contributions from feed-down are corrected using data-driven techniques. Correlation functions are obtained in several centrality classes and mT intervals at large mT and show the expected decrease in volume of the strongly interacting fireball for more peripheral collisions. We observe the decrease of the source size with mT, predicted by hydrodynamical calculations, out to mean mT = 2.18 GeV/c2.
Particle correlations at small relative momenta can be used to measure the space$-$time characteristics of particle production on the femtoscopic (fm=10$^{-15}$ m) level in high-energy collisions. Such correlations arise due to quantum statistics and final state interactions. We report correlations of two charged identical kaons measured in p$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV by the ALICE experiment at the LHC. The femtoscopic invariant radii and correlation strengths are extracted from the one-dimensional kaon correlation functions and are compared to those obtained in pp and Pb…
We present femtoscopic results for proton and Lambda correlation functions measured by ALICE in sqrt(sNN) = 2.76 TeV Pb-Pb collisions. Femtoscopic radii are extracted from pp, pbarpbar, and ppbar pairs. Comparisons of these radii with those from pion and kaon analyses reveal an approximate transverse mass scaling that is consistent with explanations of radial flow. Inelastic final state interactions are explored in baryon-antibaryon correlations functions to investigate their relationship with reduced proton yields at LHC energies.
The measurements of charged-particle multiplicity and transverse energy at mid-rapidity in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV are reported as a function of centrality. The fraction of the inelastic cross section recorded by the ALICE detector is estimated using a Glauber model. The results scaled by the number of participating nucleons are compared with pp collisions at the same collision energy, to similar results obtained at significantly lower energies, and with models based on different mechanisms for particle production in nuclear collisions.
We present a measurement of the nuclear modification factor of electrons from heavy- flavour hadron decays at midrapidity in Pb-Pb collisions at {\surd}sNN = 2.76 TeV. Electrons are identified in the pt range 1.5 GeV/c < pt < 6 GeV/c. A suppression is seen for pt larger than 3.5 GeV/c in the most central collisions.
A Large Ion Collider Experiment (ALICE) is one of the four large experiments at the Large Hadron Collider (LHC), and it is dedicated to the study of ultra-relativistic heavy-ion collisions, with the goal of investigating the properties of the high-density state of QCD matter produced in these collisions. The study of D meson production azimuthal anisotropy and the measurement of their elliptic flow (v2) can provide insight on the degree of thermalisation of charm quarks in the medium and on the charm hadronization mechanism. We present the measurement of the D+ and D0 meson v2 in Pb-Pb collisi…
In 2013, inclusive J/psi measurements in p-Pb collisions were performed at the LHC at sqrt(sNN) = 5.02 TeV, in order to measure the effects related to the cold nuclear matter on the J/psi production. Their evaluation is important in order to be able to disentangle hot and cold nuclear matter effects in Pb-Pb collisions. In this contribution, results on the inclusive J/psi production in p-Pb collisions, in the dimuon decay channel at forward and backward rapidity, down to zero transverse momentum, are presented and compared to theoretical models.
Two-particle femtoscopic correlations between non-identical charged particles for different charge combinations are measured in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV with ALICE at the LHC. The three-dimensional two-particle correlation functions are studied in different centrality bins. The femtoscopic source size parameter ($R_{Out}$) and emission asymmetry ($μ$) are extracted. It is observed that the average source size of the system and emission asymmetry between particles increase from peripheral to central events.
We report on studies of two-particle ΔηΔϕ angular correlations measured in proton-proton collisions at center of mass energies sqrt{s} = 0.9 TeV, sqrt{s} = 2.76 TeV and sqrt{s} = 7 TeV registered by the ALICE experiment at LHC. We present the dependence of the correlation function on the pair transverse momentum, the multiplicity of the event and the charge combination of particles in the pair. ΔηΔϕcorrelations are expected to exhibit several structures which arise from different physics mechanisms. The results are also related to the correlations obtained by femtoscopic analysis. We show that…
Femtoscopic correlations between charged pions and kaons for different charge combinations are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV with ALICE at the LHC. The three-dimensional pion-kaon ($π-{\rm K}$) correlation functions and double ratios in the out-side-long pair rest frame are studied in different centrality bins. The $π-{\rm K}$ femtoscopic source size parameter ($R_{\rm out}$) and emission asymmetry ($μ_{\rm out}$) are extracted. It is observed that the average source size of the system and the emission asymmetry between pions and kaons increase from peripheral …
Global variables, such as the charged particle multiplicity and the transverse energy are important observables to characterize Relativistic Heavy Ion collisions and to constrain model calculations. The charged particle multiplicity dNch/deta and transverse energy dET/deta are measured at sqrt(sNN) = 2.76 TeV in Pb-Pb collisions as a function of centrality and in pp collisions. The fraction of inelastic cross section seen by the ALICE detector is calculated either using a Glauber model or the data corrected by simulations of nuclear and electromagnetic processes, or data collected with a minim…
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 ALICE experiment has measured quarkonium production in Pb-Pb collisions at \sqrt{sNN} = 2.76 TeV and in p-Pb collisions at \sqrt{sNN} = 5.02 TeV. The measurements are performed in the dielectron de- cay channel at mid-rapidity (|yLAB| < 0.9) and in the dimuon decay channel at forward rapidity (2.5 < yLAB < 4). We focus in particular on the J/ψ nuclear modification factor measured both in Pb-Pb and p- -Pb collisions and on the Υ(1S) nuclear modification factor measured in Pb-Pb collisions.
We report on the results of femtoscopic analyses of Pb-Pb collisions at $\sqrt{s_{NN}}$=2.76 TeV and pp collisions at $\sqrt{s}$= 7 TeV with identical charged and neutral kaons. The femtoscopic correlations allow one to measure the space-time characteristics of particle production using particle correlations due to the effects of quantum statistics for identical particles and final state interaction for both identical and non-identical ones. Small contributions from resonance decays make kaon femtoscopy an ideal tool for the correlation studies. In conjunction with pion and proton femtoscopy, …
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.
We present the first measurements of femtoscopic correlations between the K$^0_{\rm S}$ and K$^{\rm \pm}$ particles in pp collisions at $\sqrt{s}=7$ TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the $a_0(980)$ resonance. The extracted kaon source radius and correlation strength parameters for K$^0_{\rm S}$K$^{\rm -}$ are found to be equal within the experimental uncertainties to those for K$^0_{\rm S}$K$^{\rm +}$. Results of the present study are compared with those from identical-kaon femtoscopic …
In heavy-ion collisions at the LHC a hot and dense medium of deconfided partons, the Quark-Gluon Plasma (QGP), is created. Its global properties can be characterized by the measurements of particles in the low transverse momentum (or "soft") regime, which represent the majority of created particles. In this report we outline a selection of measurements of the soft probes by the ALICE experiment in pp, p--Pb, and Pb--Pb collisions. The paper focuses on recent flow measurements via angular correlations and femtoscopic studies. The first ever preliminary analysis of $\mathrm{K}^0_{\rm S}\mathrm{K…
Femtoscopy is a technique enabling measurements of the space-time characteristics of particle-emitting sources. However, the femtoscopic analysis is also sensitive to the interaction cross-section. In this paper we show the first preliminary measurements of $\rm K^0_SK^{\pm}$ correlation functions in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV. These correlations originate from the final-state interactions which proceed through the $a_0(980)$ resonance only and can be employed to constrain its parameters. A similar approach can be applied to baryon pairs to extract the unknown interaction…
We present the first ever measurements of femtoscopic correlations between the K$^0_{\rm S}$ and K$^{\rm \pm}$ particles. The analysis was performed on the data from Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the $a_0(980)$ resonance. The extracted kaon source radius and correlation strength parameters for K$^0_{\rm S}$K$^{\rm -}$ are found to be equal within the experimental uncertainties to those for K$^0_{\rm S}$K$^{\rm +}$. Comparing the results of the p…
Correlations of two charged identical kaons (${\rm K}^{\rm ch}{\rm K}^{\rm ch}$) are measured in pp collisions at $\sqrt{s}=7$~TeV by the ALICE experiment at the Large Hadron Collider (LHC). One-dimensional ${\rm K}^{\rm ch}{\rm K}^{\rm ch}$ correlation functions are constructed in three multiplicity and four transverse momentum ranges. The ${\rm K}^{\rm ch}{\rm K}^{\rm ch}$ femtoscopic source parameters $R$ and $λ$ are extracted. The ${\rm K}^{\rm ch}{\rm K}^{\rm ch}$ correlations show a slight increase of femtoscopic radii with increasing multiplicity and a slight decrease of radii with incr…
The ALICE experiment is a dedicated heavy ion physics detector at the LHC with unique capabilities for studying identified particle production. In this proceeding preliminary results for RAA for pi and K+p (sum), are reported, based on measurements in pp at sqrt(s) = 2.76 TeV and Pb-Pb at sqrt(sNN) = 2.76 TeV. The results are compared to theoretical predictions and measurements at RHIC.
In this report, femtoscopic measurements with proton-proton, antiproton-antiproton, proton-antiproton, proton-antilambda, antiproton-lambda and lambda-antilambda pairs in Pb-Pb collisions at sqrt(s_NN)=2.76 TeV registered by ALICE at the LHC are presented. Emission source sizes extracted from the correlation analysis with (anti)protons grow with the event multiplicity, as expected. A method to extract the interaction potentials (e.g. for proton-antilambda and antiproton-lambda pairs) based on femtoscopy analysis is discussed. The importance of taking into account the so-called residual correla…
Two-particle correlation functions were measured for $\rm p\overline{p}$, $\rm p\overlineΛ$, $\rm \overline{p}Λ$, and $Λ\overlineΛ$ pairs in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV and $\sqrt{s_{\rm NN}}=5.02$ TeV recorded by the ALICE detector. From a simultaneous fit to all obtained correlation functions, real and imaginary components of the scattering lengths, as well as the effective ranges, were extracted for combined $\rm p\overlineΛ$ and $\rm \overline{p}Λ$ pairs and, for the first time, for $Λ\overlineΛ$ pairs. Effective averaged scattering parameters for heavier baryon-antiba…
Measurements of spectra of identified particles produced in jets represent an important tool for understanding the interplay of various hadronisation mechanisms which contribute to particle production in the hot and dense medium created in ultra-relativistic heavy-ion collisions. In this contribution, we present the measurements of the pT spectra of Λ baryons and K0S mesons produced in charged jets in Pb--Pb collisions at sqrt(sNN) = 2.76 TeV and in p--Pb collisions at sqrt(sNN) = 5.02 TeV. The results are obtained with the ALICE detector at the LHC, exploiting the excellent particle identific…
ALICE measured transverse momentum spectra of pi0 and eta mesons via the two photon decay in pp collisions at sqrt(s)=0.9, 2.76 and 7 TeV and Pb-Pb collisions at sqrt(sNN)=2.76 TeV. NLO pQCD calculations agree with p-p measurements at 0.9 TeV, but overestimate the data at 2.76 and 7 TeV. The nuclear modification factor for neutral pions shows a strong suppression of high-pt particle production in central Pb-Pb collisions. Raw spectra of charged particle jets have been measured in Pb-Pb collisions. Detailed studies of background fluctuations have been performed and will allow us to unfold the s…
The strong fluctuations in the initial energy density of heavy-ion collisions allow an efficient selection of events corresponding to a specific initial geometry. For such "shape engineered events", the elliptic flow coefficient, $v_2$, of unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\snn = 2.76$ TeV is measured by the ALICE collaboration. $v_2$ obtained with the event plane method at mid-rapidity, $|η|<0.8$, is reported for different collision centralities as a function of transverse momentum, $\pt$, out to $\pt=20$ GeV/$c$. The measured $v_2$ for the shape…
Using the unique capabilities of the ALICE detectors for particle identification, different measurements have been performed to study the properties of the hot and dense matter created in the Pb-Pb collisions at sqrt(sNN)= 2.76 TeV. The analysis of the p-Pb data at sqrt(sNN) = 5.02 TeV reveals that the suppression of high pt hadrons observed in heavy nuclei collisions can not be explained as due to initial state effects. The systems created in the p-Pb collisions do not show evidence of jet quenching but, surprisingly, exhibit characteristics of flow. In this paper a review of the main results…
In this contribution, recent ALICE measurements of the production cross section of single electrons, single muons and open charmed mesons in proton-proton collisions at sqrt(s) = 7 TeV are reported. The data are compared to next-to-leading-order perturbative QCD calculations. First open charm signals in Pb-Pb collisions at sqrt(sNN) = 2.76 TeV are shown.
We report a measurement of transverse momentum spectra of jets detected with the ALICE detector in Pb-Pb collisions at sqrt(sNN)=2.76 TeV. Jets are reconstructed from charged particles using the anti-kt jet algorithm. The background from soft particle production is determined for each event and subtracted. The remaining influence of underlying event fluctuations is quantified by embedding different probes into heavy-ion data. The reconstructed transverse momentum spectrum is corrected for background fluctuations by unfolding. We compare the inclusive jet spectra reconstructed with R=0.2 and R=…
We present first results on the production of nuclei and antinuclei such as (anti)deuterons, (anti)tritons, (anti)3He and (anti)4He in pp collisions at $\s$ = 7 TeV and Pb-Pb collisions at $\sNN$ = 2.76 TeV. These particles are identified using their energy loss (dE/dx) information in the Time Projection Chamber of the ALICE experiment. The Inner Tracking System gives a precise determination of the event vertex, by which primary and secondary particles are separated. The high statistics of over 360 million events for pp and 16 million events for Pb-Pb collisions give a significant number of li…
Measurements of particle production in proton-nucleus collisions provide a reference to disentangle final state effects, i.e. signatures of the formation of a deconfined hot medium, from initial state effects, already present in cold nuclear matter. Since many initial state effects are expected to vary as a function of the number of collisions suffered by the incoming proton, it is crucial to estimate the centrality of the collision. In p-Pb collisions categorization of events into different centrality classes using a particle multiplicity distribution is complicated by the low particle multip…
We present measurements of untriggered di-hadron correlations as a function of centrality in Pb-Pb \sNN collisions, for charged hadrons with $p_{T} > 0.15$ GeV$/c$. These measurements provide a map of the bulk correlation structures in heavy-ion collisions. Contributions to these structures may come from jets, initial density fluctuations, elliptic flow, resonances, and/or momentum conservation. We decompose the measured correlation functions via a multi-parameter fit in order to extract the nearside Gaussian, the longer range $Δη$ correlation often referred to as the soft ridge. The effect of…
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 mult…
Studies of jet production can provide information about the properties of the hot and dense strongly interacting matter created in ultra-relativistic heavy-ion collisions. Specifically, measurement of strange particles in jets may clarify the role of fragmentation processes in the anomalous baryon to meson ratio at intermediate particle pT that was observed in PbPb and, to a lesser extent, in pPb collisions. In this contribution, measurements of the pT spectra of Lambda and Antilambda baryons and K0s mesons produced in association with charged jets in PbPb collisions at sqrt(sNN)=2.76 TeV and …
Quantum interference effects enhanced in $π^+p$ femtoscopic correlation functions
Shenzhen University（深圳大学）；Beihang University（北京航空航天大学）；École Centrale de Pékin/School of General Engineering, Beihang University（北京航空航天大学中法工程师学院）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）
对 ALICE 合作组在√s = 13 TeV 的高多重 pp 碰撞中测量的π⁺p 飞秒关联函数全面分析。用含高斯源的公式及数据驱动的πN 分波振幅，考虑散射和衰变贡献，再现数据及 mT 依赖，发现 140 MeV/c 峰源于量子干涉。
We present the results of two-pion Bose-Einstein correlations measured in Pb--Pb collisions at a center-of-mass energy sqrt(s_NN) = 2.76 TeV recorded by ALICE at the Large Hadron Collider. These types of correlations allow to extract, using the technique of femtoscopy (also known as Hanburry-Brown Twiss interferometry, or shortly HBT), the space-time characteristics of the source from the correlation calculated as a function of the pair momentum difference. The femtoscopic analysis was performed using both the Spherical Harmonics decomposition and the standard 3D Cartesian representation of th…
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.
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.
Femtoscopy of non-central heavy ion collisions provides access to information on the geometry of the effective pion-emitting source. In particular, the source shape can be studied by measuring femtoscopic radii as a function of the pion emission angle relative to the collision symmetry planes. We present the results of azimuthally differential femtoscopy of Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV at the LHC relative to the second harmonic event plane. We observe a clear oscillation of the extracted radii as a function of the emission angle. We find that $R_{side}$ and $R_{out}$ oscillate …
In recent years the femtoscopy technique has been used by the ALICE Collaboration in small colliding systems at the LHC to investigate the strong-interaction of hadron pairs in the low-energy regime. The extension of this technique to the study of many-body correlations aims to deliver in the next years the first experimental measurements of the genuine many-hadron interactions, provided that the contributions due to the lower order terms are properly accounted for. In this paper we present a method that allows to determine the residual lower order contributions to the three-body correlation f…
The global polarization of the $Λ$ and $\barΛ$ hyperons ($P_{\rm H}$) has been measured in Pb--Pb collisions at $\sNN=$ 2.76 TeV and 5.02 TeV in ALICE at the Large Hadron Collider (LHC). The hyperon global polarization is found to be consistent with zero at both collision energies. The local polarization of the $Λ$ and $\barΛ$ hyperons along the beam ($z$) direction, $P_{\rm z}$, has also been measured in Pb--Pb collisions at $\sNN=5.02$ TeV. The $P_{\rm z}$, measured as a function of the hyperon emission angle relative to the second harmonic symmetry plane, exhibits a second harmonic sine mod…
Identical neutral kaon pair correlations are measured in $\sqrt{s}=7$ TeV pp collisions in the ALICE experiment. One-dimensional K$^0_s$K$^0_s$ 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 f${\rm i}$t includes quantum statistics and final-state interactions of the a$_0$/f$_0$ resonance. K$^0_s$K$^0_s$ correlations show an increase in radius for increasing multiplicity and a slight decreas…
From studies of single-particle spectra, particle correlations, and jet production in heavy-ion collisions we can obtain information about the density and the dynamic properties of the Quark-Gluon Plasma (QGP). The observed suppression of high-pT particle production (RAA) and away-side jets (IAA) is generally attributed to energy loss of partons as they propagate through the plasma. We present the results obtained from the analysis of Pb-Pb collisions at sqrt (sNN) = 2.76 TeV recorded by ALICE in November 2010. The nuclear modification factors RAA and IAA, and the status of full jet reconstruc…
Azimuthally differential femtoscopic measurements, being sensitive to spatio-temporal characteristics of the source as well as to the collective velocity fields at freeze-out, provide very important information on the nature and dynamics of the system evolution. While the HBT radii modulations relative to the second harmonic event plane reflect mostly the spatial geometry of the source, the third harmonic results are mostly defined by the velocity fields. Radii variations with respect to the third harmonic event plane unambiguously signal a collective expansion and anisotropy in the flow field…
The study of single-particle and jet production in heavy-ion collisions provides insights into the density of the medium and the energy-loss mechanisms. The observed suppression of high-$\pt$ particle production is generally attributed to energy loss of partons as they propagate through the hot and dense QCD medium - Quark-Gluon-Plasma (QGP). Such measurements allow the characterization of the QGP, the deconfined state of quarks and gluons, predicted by QCD. In these proceedings we present the analysis results of Pb--Pb collisions at $\sqrt{\sNN}=2.76$ TeV recorded by ALICE. The nuclear modifi…
The first measurements of the scattering parameters of $Λ$K pairs in all three charge combinations ($Λ$K$^{+}$, $Λ$K$^{-}$, and $Λ\mathrm{K^{0}_{S}}$) are presented. The results are achieved through a femtoscopic analysis of $Λ$K correlations in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV recorded by ALICE at the LHC. The femtoscopic correlations result from strong final-state interactions, and are fit with a parametrization allowing for both the characterization of the pair emission source and the measurement of the scattering parameters for the particle pairs. Extensive studies w…
We report on the high statistics two-pion correlation functions from pp collisions at $\sqrt{s}=0.9$ TeV and $\sqrt{s}$=7 TeV, measured by the ALICE experiment at the Large Hadron Collider. The correlation functions as well as the extracted source radii scale with event multiplicity and pair momentum. When analyzed in the same multiplicity and pair transverse momentum range, the correlation is similar at the two collision energies. A three-dimensional femtoscopic analysis shows an increase of the emission zone with increasing event multiplicity as well as decreasing homogeneity lengths with in…
We report a measurement of transverse momentum spectra of jets detected with the ALICE detector in Pb-Pb collisions at $\sNN=2.76$ TeV. Jets are reconstructed from charged particles using the anti-\kt jet algorithm. The transverse momentum of tracks is measured down to 150 MeV/$c$ which gives access to the low \pt fragments of the jet. The background from soft particle production is determined for each event and subtracted. The remaining influence of underlying event fluctuations is quantified by embedding different probes into heavy-ion data. The reconstructed transverse momentum spectrum is …
We report on the results of femtoscopic analysis of Pb-Pb collisions at sqrt(s_NN)=2.76 TeV and pp collisions at sqrt(s)=0.9, 2.76 and 7 TeV with identical pions and kaons. Detailed femtoscopy studies in heavy-ion collisions at SPS and RHIC have shown that emission region sizes ("HBT radii") decrease with increasing pair transverse momentum k_T, which is understood as a manifestation of the collective behavior of matter. The trend was predicted to persist at the LHC. The data from Pb-Pb collisions confirm the existence of a flowing medium and provide strict constraints on the dynamical models.…
The size of the particle emission region in high-energy collisions can be deduced using the femtoscopic correlations of particle pairs at low relative momentum. Such correlations arise due to quantum statistics and Coulomb and strong final state interactions. In this paper, results are presented from femtoscopic analyses of $π^{\pm}π^{\pm}$, ${\rm K}^{\pm}{\rm K}^{\pm}$, ${\rm K}^{0}_S{\rm K}^{0}_S$, ${\rm pp}$, and ${\rm \overline{p}}{\rm \overline{p}}$ correlations from Pb-Pb collisions at $\sqrt{s_{\mathrm {NN}}}=2.76$ TeV by the ALICE experiment at the LHC. One-dimensional radii of the sys…
We present a calculation of the elliptic flow of electrons from beauty-hadron decays in semi-central Pb--Pb collisions at centre-of-mass energy per colliding nucleon pair, represented as $\sqrt{s_{\rm NN}}$, of 2.76 TeV. The result is obtained by the subtraction of the charm quark contribution in the elliptic flow of electrons from heavy-flavour hadron decays in semi-central Pb--Pb collisions at \snn = 2.76 TeV recently made publicly available by the ALICE collaboration.
We present the results of three-dimensional femtoscopic analyses for charged and neutral kaons recorded by ALICE in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. Femtoscopy is used to measure the space-time characteristics of particle production from the effects of quantum statistics and final-state interactions in two-particle correlations. Kaon femtoscopy is an important supplement to that of pions because it allows one to distinguish between different model scenarios working equally well for pions. In particular, we compare the measured 3D kaon radii with a purely hydrodynamical calc…
In this paper, the first femtoscopic analysis of pion-kaon correlations at the LHC is reported. The analysis was performed on the Pb-Pb collision data at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV recorded with the ALICE detector. The non-identical particle correlations probe the spatio-temporal separation between sources of different particle species as well as the average source size of the emitting system. The sizes of the pion and kaon sources increase with centrality, and pions are emitted closer to the centre of the system and/or later than kaons. This is naturally expected in a system with strong …
This Letter presents the first direct investigation of the p-$Σ^{0}$ interaction, using the femtoscopy technique in high-multiplicity pp collisions at $\sqrt{s}$ = 13 TeV measured by the ALICE detector. The $Σ^{0}$ is reconstructed via the decay channel to $Λγ$, and the subsequent decay of $Λ$ to p$π^-$. The photon is detected via the conversion in material to e$^{+}$e$^{-}$ pairs exploiting the unique capability of the ALICE detector to measure electrons at low transverse momenta. The measured p-$Σ^{0}$ correlation indicates a shallow strong interaction. The comparison of the data to several …
