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Item type:Publication, Measurement of inclusive charged-particle jet production in pp and p–Pb collisions(Springer Science and Business Media Deutschland GmbH, 2024-05-01)Measurements of inclusive charged-particle jet production in pp and p-Pb collisions at center-of-mass energy per nucleon-nucleon collision sNN = 5.02 TeV and the corresponding nuclear modification factor RpPbchjet are presented, using data collected with the ALICE detector at the LHC. Jets are reconstructed in the central rapidity region |ηjet| < 0.5 from charged particles using the anti-kT algorithm with resolution parameters R = 0.2, 0.3, and 0.4. The pT-differential inclusive production cross section of charged-particle jets, as well as the corresponding cross section ratios, are reported for pp and p-Pb collisions in the transverse momentum range 10 <pT,jetch< 140 GeV/c and 10 <pT,jetch< 160 GeV/c, respectively, together with the nuclear modification factor RpPbchjet in the range 10 <pT,jetch< 140 GeV/c. The analysis extends the pT range of the previously-reported charged-particle jet measurements by the ALICE Collaboration. The nuclear modification factor is found to be consistent with one and independent of the jet resolution parameter with the improved precision of this study, indicating that the possible influence of cold nuclear matter effects on the production cross section of charged-particle jets in p-Pb collisions at sNN = 5.02 TeV is smaller than the current precision. The obtained results are in agreement with other minimum bias jet measurements available for RHIC and LHC energies, and are well reproduced by the NLO perturbative QCD Powheg calculations with parton shower provided by Pythia8 as well as by Jetscape simulations. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Production of Pions, Kaons, and Protons as a Function of the Relative Transverse Activity Classifier in pp Collisions at √s = 13 TeV(Springer Science and Business Media Deutschland GmbH, 2023-06-01)The production of π ±, K±, and (p ¯) p is measured in pp collisions at s = 13 TeV in different topological regions of the events. Particle transverse momentum (p T) spectra are measured in the “toward”, “transverse”, and “away” angular regions defined with respect to the direction of the leading particle in the event. While the toward and away regions contain the fragmentation products of the near-side and away-side jets, respectively, the transverse region is dominated by particles from the Underlying Event (UE). The relative transverse activity classifier, R T = N T/〈N T〉, is used to group events according to their UE activity, where N T is the measured charged-particle multiplicity per event in the transverse region and 〈N T〉 is the mean value over all the analysed events. The first measurements of identified particle p T spectra as a function of R T in the three topological regions are reported. It is found that the yield of high transverse momentum particles relative to the R T-integrated measurement decreases with increasing R T in both the toward and the away regions, indicating that the softer UE dominates particle production as R T increases and validating that R T can be used to control the magnitude of the UE. Conversely, the spectral shapes in the transverse region harden significantly with increasing R T. This hardening follows a mass ordering, being more significant for heavier particles. Finally, it is observed that the p T-differential particle ratios (p+p¯)/(π++π−) and (K+ + K−)/(π + + π −) in the low UE limit (R T → 0) approach expectations from Monte Carlo generators such as PYTHIA 8 with Monash 2013 tune and EPOS LHC, where the jet-fragmentation models have been tuned to reproduce e+e− results. [Figure not available: see fulltext.] - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Production of KS0, Λ (Λ̄), Ξ±, and Ω± in Jets and in the Underlying Event in pp and p–Pb Collisions(Springer Science and Business Media Deutschland GmbH, 2023-07-01)The production of strange hadrons (KS0 , Λ, Ξ±, and Ω±), baryon-to-meson ratios (Λ/ KS0 , Ξ/ KS0 , and Ω/ KS0), and baryon-to-baryon ratios (Ξ/Λ, Ω/Λ, and Ω/Ξ) associated with jets and the underlying event were measured as a function of transverse momentum (p T) in pp collisions at s = 13 TeV and p Pb collisions at sNN = 5.02 TeV with the ALICE detector at the LHC. The inclusive production of the same particle species and the corresponding ratios are also reported. The production of multi-strange hadrons, Ξ± and Ω±, and their associated particle ratios in jets and in the underlying event are measured for the first time. In both pp and p–Pb collisions, the baryon-to-meson and baryon-to-baryon yield ratios measured in jets differ from the inclusive particle production for low and intermediate hadron p T(0.6–6 GeV/c). Ratios measured in the underlying event are in turn similar to those measured for inclusive particle production. In pp collisions, the particle production in jets is compared with Pythia 8 predictions with three colour-reconnection implementation modes. None of them fully reproduces the data in the measured hadron p T region. The maximum deviation is observed for Ξ± and Ω± which reaches a factor of about six. The event multiplicity dependence is further investigated in p−Pb collisions. In contrast to what is observed in the underlying event, there is no significant event-multiplicity dependence for particle production in jets. The presented measurements provide novel constraints on hadronisation and its Monte Carlo description. In particular, they demonstrate that the fragmentation of jets alone is insufficient to describe the strange and multi-strange particle production in hadronic collisions at LHC energies. [Figure not available: see fulltext.]. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Measurement of the Non-Prompt D-Meson Fraction as a Function of Multiplicity in Proton-Proton Collisions at √s = 13 TeV(Springer Science and Business Media Deutschland GmbH, 2023-10-01)The fractions of non-prompt (i.e. originating from beauty-hadron decays) D0 and D+ mesons with respect to the inclusive yield are measured as a function of the charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy of s = 13 TeV with the ALICE detector at the LHC. The results are reported in intervals of transverse momentum (p T) and integrated in the range 1 < p T < 24 GeV/c. The fraction of non-prompt D0 and D+ mesons is found to increase slightly as a function of p T in all the measured multiplicity intervals, while no significant dependence on the charged-particle multiplicity is observed. In order to investigate the production and hadronisation mechanisms of charm and beauty quarks, the results are compared to PYTHIA 8 as well as EPOS 3 and EPOS 4 Monte Carlo simulations, and to calculations based on the colour glass condensate including three-pomeron fusion. [Figure not available: see fulltext.]. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, J/ψ Production at Midrapidity in p-Pb Collisions at √sNN = 8.16 TeV(Springer Science and Business Media Deutschland GmbH, 2023-07-01)The production of inclusive, prompt and non-prompt J/ψ was studied for the first time at midrapidity (−1.37 < y cms < 0.43) in p-Pb collisions at sNN = 8.16 TeV with the ALICE detector at the LHC. The inclusive J/ψ mesons were reconstructed in the dielectron decay channel in the transverse momentum (p T) interval 0 < p T < 14 GeV/c and the prompt and non-prompt contributions were separated on a statistical basis for p T > 2 GeV/c. The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13 μb −1. The proton-proton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the p T-differential J/ψ production cross sections. The p T-differential nuclear modification factors R pPb of inclusive, prompt, and non-prompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing. [Figure not available: see fulltext.]