In these proceedings, measurements of angular correlations between hadron pairs in pp collisions obtained by the ALICE experiment at the LHC are presented and compared with phenomenological predictions. Correlations between particles carrying the same and opposite quantum numbers are studied to understand the hadron production mechanism, and the difference between same-sign and opposite-sign correlations is used to probe charge-dependent effects in particle production. Correlation measurements dominated by minijet fragmentation agree well with the models, but other results, in particular correlations between baryons and strange hadrons, are not yet understood.
These proceedings summarise recent measurements of angular correlations between the $Ξ$ baryon and identified hadrons in pp collisions at $\sqrt{s}=13\,\mathrm{TeV}$ using the ALICE detector. The results are compared with both string-based (PYTHIA8 with extensions) and core-corona (EPOS-LHC) models, to improve our understanding of strangeness and baryon production in small systems. The results favour baryon production through string junctions over diquark breaking, but the PYTHIA models fail at describing the relatively wide $Ξ-$strangeness jet peak, indicating stronger diffusion of strange qu…
An overview of ALICE results on the measurement of J/ψ production in pp collisions at $\sqrt{s}$ = 7 TeV collected during the LHC Run-1 period is presented, as well as first results at forward rapidity from pp collisions at $\sqrt{s}$ = 13 TeV collected during the LHC Run-2 period. In particular, the measurement of J/ψ production as a function of transverse momentum and charged-particle multiplicity are discussed and compared to theoretical model calculations.
The production of $\mathrm{K^0_S}$, $Λ$ and $Ξ$ is measured in jets and underlying events in pp collisions at $\sqrt{s}$ = 13 TeV with ALICE detectors. The corresponding $Λ/\mathrm{K^0_S}$ and $Ξ/Λ$ ratios are presented as a function of transverse momentum. The hard scatterings are tagged by charged-particle jets ,which are reconstructed with the anti-$k_\mathrm{T}$ algorithm using a resolution parameter $R$ = 0.4. The flow-like correlations and the enhanced production of multi-strange hadrons in small colliding systems may be described by soft components.
Light vector meson production at the LHC with the ALICE detector
pp碰撞中光矢量介子产生（ρ，ω，π）的测量为研究LHC能区的软量子色动力学（QCD）过程提供了新的视角。在这种情况下的计算是基于QCD启发的唯象模型，必须调整到数据。此外，轻矢量介子的产生为高能重离子碰撞提供了参考。利用ALICE实验测量了7 TeV pp碰撞中的π和ω微分截面，以及2.76 TeV pp碰撞中的π截面，测量了它们衰变到μ子对的过程，测量的快度区间为2.5 < y < 4。
High-energy collisions in ALICE allow for the study of soft and hard QCD particle production. The correlation between transverse momentum spectra and event multiplicity is a sensitive observable providing insights into the different production mechanisms. In these proceedings we report on this observable for unidentified charged-particles, obtained using a 2d-unfolding procedure. Particle production is compared at different collision energies, as well as for pp, p--Pb and Pb--Pb collisions at the same energy. In order to understand the role of autocorrelations in small systems, it was proposed…
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 availability at the LHC of the largest collision energy in pp collisions allows a significant advance in the measurement of $J/ψ$ production as function of event multiplicity. The interesting relative increase observed with data at the LHC at $\sqrt{s} = 7\,\mathrm{TeV}$ and at RHIC at $\sqrt{s} = 0.2\,\mathrm{TeV}$ is studied now at unprecedented multiplicities at $\sqrt{s} = 13\,\mathrm{TeV}$. The measurement at mid-rapidity in the dielectron channel with ALICE is presented and discussed in comparison to predictions from available theoretical models and to data at lower energies.
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…
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 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.
Results for high multiplicity pp and p-Pb collisions at the LHC have revealed that these small collision systems exhibit features of collectivity. To understand the origin of these unexpected phenomena, the relative transverse activity classifier ($R_{\rm{T}}$) can be exploited as a tool to disentangle soft and hard particle production, by studying the yield of charged particles in different topological regions associated with transverse momentum trigger particles. This allows to study system size dependence of charged particle production of different origins and in particular search for jet-q…
This contribution focuses on the latest studies of heavy-flavour jets performed with the ALICE detector. The measurements of the jet momentum fraction carried by the D meson in pp collisions at $\sqrt{s}=5.02$ TeV and $13\ \mathrm{TeV}$ will be presented. The comparison to POWHEG+PYTHIA will be shown. Moreover, the first measurement at the LHC of the jet-momentum fraction carried by the $\mathrm{Λ_c^+}$ baryon in pp collisions at $\sqrt{s}=13\ \mathrm{TeV}$ will be reported. Production of heavy-flavour jets in pp collisions at $\sqrt{s}=5.02\ \mathrm{TeV}$ will be also addressed with charged j…
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.
At LHC energies, the charged-particle multiplicity dependence of particle production is a topic of considerable interest in $pp$ collisions. It has been argued that multiple partonic interactions play an important role in particle production mechanisms, not only affecting the soft processes but also the hard processes. Recently, ALICE has measured $J/ψ$ production as a function of charged-particle multiplicity to study the correlation between soft and hard processes. In this contribution, we present the $J/ψ$ production versus multiplicity for $pp$ and $p-Pb$ collisions measured by ALICE. We c…
The study of identified particle production as a function of transverse momentum ($p_{\text{T}}$) and event multiplicity in proton-proton (pp) collisions at different center-of-mass energies ($\sqrt{s}$) is a key tool for understanding similarities and differences between small and large collisions systems. We report on the production of $π^{\pm}$, $K^{\pm}$, $K^{0}_{S}$, $p (\bar{p})$, $Λ(\barΛ)$, $Ξ^{\pm}$ and $Ω^{\pm}$ measured in pp collisions in a wide range of center-of-mass energies with ALICE. The multiplicity dependence of identified particle yields is presented for $\sqrt{s} = \textr…
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…
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.
Measurements of jet production and jet properties in pp collisions provide a test of perturbative quantum chromodynamics (pQCD) and form a baseline for similar measurements in heavy ion (A--A) collisions. In this contribution, we report recent ALICE measurements of charged-particle jet production and intra-jet properties, including mean charged-constituent multiplicity and fragmentation distribution for leading jets, in minimum bias pp collisions at $\sqrt{s} = 13\,$TeV. In addition, the event multiplicity dependence of jet production and jet properties in pp collisions at $\sqrt{s} = 13\,$TeV…
Hadronic resonance production with the ALICE experiment in pp and Pb-Pb collisions at LHC energies
用ALICE实验测量了$\sqrt{s}=7$ TeV pp碰撞和$\sqrt{s_{_\mathrm{NN}}}=2.76$ TeV Pb-Pb碰撞中的强子共振$\mathrm{K}^{*}(892)^{0}$、$ϕ$（1020）和$Σ(1385)^{\pm}$。讨论了横动量谱、粒子比、核修正因子以及与模型预测的比较。此外，ALICE的结果进行了比较，在RHIC能源获得的数据。
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.
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.
In these proceedings, two multi-differential analyses performed in pp collisions collected by the ALICE collaboration during the LHC Run 2 are presented. One investigates the dependence of strange particle production with multiplicity and effective energy, whereas the other clarifies how strangeness enhancement is correlated to the leading jet in the event. The results suggest that strangeness production at the LHC depends strongly on effective energy, and originates dominantly from the transverse region with respect to the leading jet direction.
The multiplicity dependence of charmed-particle production can unveil new information on processes taking part at the parton level and on the interplay of soft and hard production mechanisms in collisions of relativistic hadrons. In this contribution, we report on multiplicity-differential measurements of $\rm{J}/ψ$ in pp and p-Pb collisions studied by the ALICE Collaboration. Comparisons between measurements at different energies are drawn as well as comparisons with $\rm{D}$ mesons. We also discuss the comparison with different theoretical predictions.
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.
Measurements of the heavy-flavour hadron production are a powerful tool to study the nature of strong interaction and to understand the properties of nuclear matter that is created in ultra-relativistic hadron-hadron collisions. The excellent tracking and vertexing capabilities of the ALICE experiment, together with its particle identification systems, allow for an efficient identification and reconstruction of decays of hadrons that contain heavy quarks. A selection of recent measurements on open heavy-flavour production from pp collisions at $\sqrt{s}=7$ TeV and p--Pb collisions at $\sqrt{s_…
Measurements of electroweak-bosons in heavy-ion collisions with ALICE are reported. They are measured at large rapidities, via their (di)muonic decay: Z $\rightarrow μ^+ μ^-$ and W$^\pm \rightarrow μ^\pm ν$. The Z production and nuclear modification factor in Pb--Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 5.02 TeV are presented and compared to theoretical predictions with or without nuclear modifications of the Parton Distribution Functions. Measurements of electroweak-boson production in p--Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 5.02 and 8.16 TeV are also presented and discussed.
