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Item type:Publication, Σ(1385)± Resonance Production in Pb–Pb Collisions at √sNN = 5.02 TeV(Institute for Ionics, 2023-05-01)Hadronic resonances are used to probe the hadron gas produced in the late stage of heavy-ion collisions since they decay on the same timescale, of the order of 1–10 fm/c, as the decoupling time of the system. In the hadron gas, (pseudo)elastic scatterings among the products of resonances that decayed before the kinetic freeze-out and regeneration processes counteract each other, the net effect depending on the resonance lifetime, the duration of the hadronic phase, and the hadronic cross sections at play. In this context, the Σ (1385) ± particle is of particular interest as models predict that regeneration dominates over rescattering despite its relatively short lifetime of about 5.5 fm/c. The first measurement of the Σ (1385) ± resonance production at midrapidity in Pb–Pb collisions at sNN=5.02 TeV with the ALICE detector is presented in this Letter. The resonances are reconstructed via their hadronic decay channel, Λ π , as a function of the transverse momentum (pT) and the collision centrality. The results are discussed in comparison with the measured yield of pions and with expectations from the statistical hadronization model as well as commonly employed event generators, including PYTHIA8/Angantyr and EPOS3 coupled to the UrQMD hadronic cascade afterburner. None of the models can describe the data. For Σ (1385) ± , a similar behaviour as K ∗(892) is observed in data unlike the predictions of EPOS3 with afterburner.8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Multiplicity and Rapidity Dependence of K∗(892) and ϕ(1020) Production in p–Pb Collisions at √sNN = 5.02 TeV(Institute for Ionics, 2023-06-01)The transverse-momentum (pT) spectra of K ∗(892)0 and ϕ(1020) measured with the ALICE detector up to pT = 16 GeV/c in the rapidity range - 1.2 < y< 0.3 , in p–Pb collisions at the center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV are presented as a function of charged particle multiplicity and rapidity. The measured pT distributions show a dependence on both multiplicity and rapidity at low pT whereas no significant dependence is observed at high pT . A rapidity dependence is observed in the pT -integrated yield (dN/dy), whereas the mean transverse momentum (⟨ pT⟩) shows a flat behavior as a function of rapidity. The rapidity asymmetry (Yasym) at low pT (< 5 GeV/c) is more significant for higher multiplicity classes. At high pT , no significant rapidity asymmetry is observed in any of the multiplicity classes. Both K ∗(892)0 and ϕ(1020) show similar Yasym . The nuclear modification factor (QCP) as a function of pT shows a Cronin-like enhancement at intermediate pT , which is more prominent at higher rapidities (Pb-going direction) and in higher multiplicity classes. At high pT (> 5 GeV/ c), the QCP values are greater than unity and no significant rapidity dependence is observed. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Inclusive Photon Production at Forward Rapidities in pp and p–Pb Collisions at √sNN = 5.02 TeV(Institute for Ionics, 2023-07-01)A study of multiplicity and pseudorapidity distributions of inclusive photons measured in pp and p–Pb collisions at a center-of-mass energy per nucleon–nucleon collision of sNN=5.02 TeV using the ALICE detector in the forward pseudorapidity region 2.3 <ηlab< 3.9 is presented. Measurements in p–Pb collisions are reported for two beam configurations in which the directions of the proton and lead ion beam were reversed. The pseudorapidity distributions in p–Pb collisions are obtained for seven centrality classes which are defined based on different event activity estimators, i.e., the charged-particle multiplicity measured at midrapidity as well as the energy deposited in a calorimeter at beam rapidity. The inclusive photon multiplicity distributions for both pp and p–Pb collisions are described by double negative binomial distributions. The pseudorapidity distributions of inclusive photons are compared to those of charged particles at midrapidity in pp collisions and for different centrality classes in p–Pb collisions. The results are compared to predictions from various Monte Carlo event generators. None of the generators considered in this paper reproduces the inclusive photon multiplicity distributions in the reported multiplicity range. The pseudorapidity distributions are, however, better described by the same generators. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, First Measurement of Λc+ Production Down to pT = 0 in pp and p-Pb Collisions at sNN = 5.02 TeV(American Physical Society, 2023-06-01)The production of prompt Λc+ baryons has been measured at midrapidity in the transverse momentum interval 0<pT<1 GeV/c for the first time, in pp and p-Pb collisions at a center-of-mass energy per nucleon-nucleon collision sNN=5.02TeV. The measurement was performed in the decay channel Λc+→pKS0 by applying new decay reconstruction techniques using a Kalman-Filter vertexing algorithm and adopting a machine-learning approach for the candidate selection. The pT-integrated Λc+ production cross sections in both collision systems were determined and used along with the measured yields in Pb-Pb collisions to compute the pT-integrated nuclear modification factors RpPb and RAA of Λc+ baryons, which are compared to model calculations that consider nuclear modification of the parton distribution functions. The Λc+/D0 baryon-to-meson yield ratio is reported for pp and p-Pb collisions. Comparisons with models that include modified hadronization processes are presented, and the implications of the results on the understanding of charm hadronization in hadronic collisions are discussed. A significant (3.7σ) modification of the mean transverse momentum of Λc+ baryons is seen in p-Pb collisions with respect to pp collisions, while the pT-integrated Λc+/D0 yield ratio was found to be consistent between the two collision systems within the uncertainties.