| 1. |
- Acharya, S., et al.
(författare)
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ALICE luminosity determination for Pb-Pb collisions at √ s NN= 5.02 TeV
- 2024
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 19:2
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Tidskriftsartikel (refereegranskat)abstract
- Luminosity determination within the ALICE experiment is based on the measurement, in van der Meer scans, of the cross sections for visible processes involving one or more detectors (visible cross sections). In 2015 and 2018, the Large Hadron Collider provided Pb-Pb collisions at a centre-of-mass energy per nucleon pair of √s NN= 5.02 TeV. Two visible cross sections, associated with particle detection in the Zero Degree Calorimeter (ZDC) and in the V0 detector, were measured in a van der Meer scan. This article describes the experimental set-up and the analysis procedure, and presents the measurement results. The analysis involves a comprehensive study of beam-related effects and an improved fitting procedure, compared to previous ALICE studies, for the extraction of the visible cross section. The resulting uncertainty of both the ZDC-based and the V0-based luminosity measurement for the full sample is 2.5%. The inelastic cross section for hadronic interactions in Pb-Pb collisions at √s NN= 5.02 TeV, obtained by efficiency correction of the V0-based visible cross section, was measured to be 7.67 ± 0.25 b, in agreement with predictions using the Glauber model. © 2024 Institute of Physics. All rights reserved.
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| 2. |
- Acharya, S., et al.
(författare)
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Measurement of the fraction of jet longitudinal momentum carried by Λc+ baryons in pp collisions
- 2024
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Ingår i: Physical Review D. - 2470-0010. ; 109:7
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Tidskriftsartikel (refereegranskat)abstract
- Recent measurements of charm-baryon production in hadronic collisions have questioned the universality of charm-quark fragmentation across different collision systems. In this work the fragmentation of charm quarks into charm baryons is probed, by presenting the first measurement of the longitudinal jet momentum fraction carried by Λc+ baryons, z∥ch, in hadronic collisions. The results are obtained in proton-proton (pp) collisions at s=13 TeV at the LHC, with Λc+ baryons and charged (track-based) jets reconstructed in the transverse momentum intervals of 3≤pTΛc+
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| 3. |
- Acharya, S., et al.
(författare)
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ψ (2S) Suppression in Pb-Pb Collisions at the LHC
- 2024
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Ingår i: Physical Review Letters. - 0031-9007. ; 132:4
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Tidskriftsartikel (refereegranskat)abstract
- The production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at √sNN=5.02 TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.5
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| 4. |
- Acharya, S., et al.
(författare)
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Charged-particle production as a function of the relative transverse activity classifier in pp, p–Pb, and Pb–Pb collisions at the LHC
- 2024
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2024:1
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum in the range 8 < < 15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier, , is used to group events according to their UE activity, where is the charged-particle multiplicity per event in the transverse region and is the mean value over the whole analysed sample. The energy dependence of the RT distributions in pp collisions at = 2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particle pT spectra as a function of RT in the three azimuthal regions in pp, p–Pb, and Pb–Pb collisions at = 5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p–Pb).
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| 5. |
- Acharya, S., et al.
(författare)
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Emergence of Long-Range Angular Correlations in Low-Multiplicity Proton-Proton Collisions
- 2024
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Ingår i: Physical Review Letters. - 0031-9007. ; 132:17
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Tidskriftsartikel (refereegranskat)abstract
- This Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at s=13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of 1.4
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| 6. |
- Acharya, S., et al.
(författare)
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Femtoscopic correlations of identical charged pions and kaons in pp collisions at s =13 TeV with event-shape selection
- 2024
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Ingår i: Physical Review C. - 2469-9985. ; 109:2
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Tidskriftsartikel (refereegranskat)abstract
- Collective behavior has been observed in high-energy heavy-ion collisions for several decades. Collectivity is driven by the high particle multiplicities that are produced in these collisions. At the CERN Large Hadron Collider (LHC), features of collectivity have also been seen in high-multiplicity proton-proton collisions that can attain particle multiplicities comparable to peripheral Pb-Pb collisions. One of the possible signatures of collective behavior is the decrease of femtoscopic radii extracted from pion and kaon pairs emitted from high-multiplicity collisions with increasing pair transverse momentum. This decrease can be described in terms of an approximate transverse mass scaling. In the present work, femtoscopic analyses are carried out by the ALICE Collaboration on charged pion and kaon pairs produced in pp collisions at s=13TeV from the LHC to study possible collectivity in pp collisions. The event-shape analysis method based on transverse sphericity is used to select for spherical versus jetlike events, and the effects of this selection on the femtoscopic radii for both charged pion and kaon pairs are studied. This is the first time this selection method has been applied to charged kaon pairs. An approximate transverse-mass scaling of the radii is found in all multiplicity ranges studied when the difference in the Lorentz boost for pions and kaons is taken into account. This observation does not support the hypothesis of collective expansion of hot and dense matter that should only occur in high-multiplicity events. A possible alternate explanation of the present results is based on a scenario of common emission conditions for pions and kaons in pp collisions for the multiplicity ranges studied. © 2024 CERN.
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| 7. |
- Acharya, S., et al.
(författare)
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First Measurement of the |t | Dependence of Incoherent J/ψ Photonuclear Production
- 2024
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Ingår i: Physical Review Letters. - 0031-9007. ; 132:16
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Tidskriftsartikel (refereegranskat)abstract
- The first measurement of the cross section for incoherent photonuclear production of J/ψ vector mesons as a function of the Mandelstam |t| variable is presented. The measurement was carried out with the ALICE detector at midrapidity, |y|
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| 8. |
- Acharya, S., et al.
(författare)
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K*(892)± resonance production in Pb-Pb collisions at sNN =5.02 TeV
- 2024
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Ingår i: Physical Review C. - 2469-9985. ; 109:4
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Tidskriftsartikel (refereegranskat)abstract
- The production of K∗(892)± meson resonance is measured at midrapidity (|y|8 GeV/c, consistent with measurements for other light-flavored hadrons. The smallest values are observed in most central collisions, indicating larger energy loss of partons traversing the dense medium. ©2024 CERN, for the ALICE Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
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| 9. |
- Acharya, S., et al.
(författare)
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Measurement of the radius dependence of charged-particle jet suppression in Pb–Pb collisions at sNN=5.02TeV
- 2024
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 849
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE Collaboration reports a differential measurement of inclusive jet suppression using pp and Pb–Pb collision data at a center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV. Charged-particle jets are reconstructed using the anti-kT algorithm with resolution parameters R=0.2, 0.3, 0.4, 0.5, and 0.6 in pp collisions and R=0.2, 0.4, 0.6 in central (0–10%), semi-central (30–50%), and peripheral (60–80%) Pb–Pb collisions. A novel approach based on machine learning is employed to mitigate the influence of jet background. This enables measurements of inclusive jet suppression in new regions of phase space, including down to the lowest jet pT≥40 GeV/c at R=0.6 in central Pb–Pb collisions. This is an important step for discriminating different models of jet quenching in the quark–gluon plasma. The transverse momentum spectra, nuclear modification factors, derived cross section, and nuclear modification factor ratios for different jet resolution parameters of charged-particle jets are presented and compared to model predictions. A mild dependence of the nuclear modification factor ratios on collision centrality and resolution parameter is observed. The results are compared to a variety of jet-quenching models with varying levels of agreement.
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| 10. |
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