| 91. |
- Acharya, S., et al.
(författare)
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Performance of the ALICE Electromagnetic Calorimeter
- 2023
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 18:8
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Tidskriftsartikel (refereegranskat)abstract
- The performance of the electromagnetic calorimeter of the ALICE experiment during operation in 2010-2018 at the Large Hadron Collider is presented. After a short introduction into the design, readout, and trigger capabilities of the detector, the procedures for data taking, reconstruction, and validation are explained. The methods used for the calibration and various derived corrections are presented in detail. Subsequently, the capabilities of the calorimeter to reconstruct and measure photons, light mesons, electrons and jets are discussed. The performance of the calorimeter is illustrated mainly with data obtained with test beams at the Proton Synchrotron and Super Proton Synchrotron or in proton-proton collisions at s = 13 TeV, and compared to simulations.
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| 92. |
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| 93. |
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| 94. |
- Acharya, S., et al.
(författare)
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Production of K∗(892)0 and φ(1020) in pp and Pb-Pb collisions at sNN =5.02 TeV
- 2022
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Ingår i: Physical Review C. - 2469-9985. ; 106:3
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Tidskriftsartikel (refereegranskat)abstract
- The production of K∗(892)0 and φ(1020) mesons in proton-proton (pp) and lead-lead (Pb-Pb) collisions at sNN = 5.02 TeV has been measured using the ALICE detector at the Large Hadron Collider (LHC). The transverse momentum (pT) distributions of K∗(892)0 and φ(1020) mesons have been measured at midrapidity (|y| 8 GeV/c, the RAA values of K∗(892)0 and φ(1020) are below unity and observed to be similar to those of pions, kaons, and (anti)protons. The RAA values at high pT (>8 GeV/c) for K∗(892)0 and φ(1020) mesons are in agreement within uncertainties for sNN= 5.02 and 2.76 TeV. © 2022 CERN.
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| 95. |
- Acharya, S., et al.
(författare)
-
Production of KS0 , Λ (Λ ¯), Ξ±, and Ω± in jets and in the underlying event in pp and p–Pb collisions
- 2023
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2023:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.]. © 2023, The Author(s).
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| 96. |
- Acharya, S., et al.
(författare)
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Production of light (anti)nuclei in pp collisions at √s=5.02 TeV
- 2022
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:4
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Tidskriftsartikel (refereegranskat)abstract
- The study of the production of nuclei and antinuclei in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper, the production of protons, deuterons and 3He and their charge conjugates at midrapidity is studied as a function of the charged-particle multiplicity in inelastic pp collisions at s=5.02 TeV using the ALICE detector. Within the uncertainties, the yields of nuclei in pp collisions at s=5.02 TeV are compatible with those in pp collisions at different energies and to those in p–Pb collisions when compared at similar multiplicities. The measurements are compared with the expectations of coalescence and Statistical Hadronisation Models. The results suggest a common formation mechanism behind the production of light nuclei in hadronic interactions and confirm that they do not depend on the collision energy but on the number of produced particles. © 2022, The Author(s).
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| 97. |
- Acharya, S., et al.
(författare)
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Production of pions, kaons, and protons as a function of the relative transverse activity classifier in pp collisions at √s = 13 TeV
- 2023
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2023:6
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Tidskriftsartikel (refereegranskat)abstract
- 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.] © 2023, The Author(s).
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| 98. |
- Acharya, S., et al.
(författare)
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Production of Λ and KS0 in jets in p–Pb collisions at sNN=5.02 TeV and pp collisions at s=7 TeV
- 2022
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 827
-
Tidskriftsartikel (refereegranskat)abstract
- The production of Λ baryons and KS0 mesons (V0 particles) was measured in p–Pb collisions at sNN=5.02 TeV and pp collisions at s=7 TeV with ALICE at the LHC. The production of these strange particles is studied separately for particles associated with hard scatterings and the underlying event to shed light on the baryon-to-meson ratio enhancement observed at intermediate transverse momentum (pT) in high multiplicity pp and p–Pb collisions. Hard scatterings are selected on an event-by-event basis with jets reconstructed with the anti-kT algorithm using charged particles. The production of strange particles associated with jets pT,jetch>10 and pT,jetch>20 GeV/c in p–Pb collisions, and with jet pT,jetch>10 GeV/c in pp collisions is reported as a function of pT. Its dependence on angular distance from the jet axis, R(V0,jet), for jets with pT,jetch>10 GeV/c in p–Pb collisions is reported as well. The pT-differential production spectra of strange particles associated with jets are found to be harder compared to that in the underlying event and both differ from the inclusive measurements. In events containing a jet, the density of the V0 particles in the underlying event is found to be larger than the density in the minimum bias events. The Λ/KS0 ratio associated with jets in p–Pb collisions is consistent with the ratio in pp collisions and follows the expectation of jets fragmenting in vacuum. On the other hand, this ratio within jets is consistently lower than the one obtained in the underlying event and it does not show the characteristic enhancement of baryons at intermediate pT often referred to as “baryon anomaly” in the inclusive measurements. © 2022 European Organization for Nuclear Research, ALICE
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| 99. |
- Acharya, S., et al.
(författare)
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Prompt and non-prompt J/ψ production cross sections at midrapidity in proton-proton collisions at √s = 5.02 and 13 TeV
- 2022
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2022:3
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Tidskriftsartikel (refereegranskat)abstract
- The production of J/ψ is measured at midrapidity (|y| < 0.9) in proton-proton collisions at s = 5.02 and 13 TeV, through the dielectron decay channel, using the ALICE detector at the Large Hadron Collider. The data sets used for the analyses correspond to integrated luminosities of Lint = 19.4 ± 0.4 nb−1 and Lint = 32.2 ± 0.5 nb−1 at s = 5.02 and 13 TeV, respectively. The fraction of non-prompt J/ψ mesons, i.e. those originating from the decay of beauty hadrons, is measured down to a transverse momentum pT = 2 GeV/c (1 GeV/c) at s = 5.02 TeV (13 TeV). The pT and rapidity (y) differential cross sections, as well as the corresponding values integrated over pT and y, are carried out separately for prompt and non-prompt J/ψ mesons. The results are compared with measurements from other experiments and theoretical calculations based on quantum chromodynamics (QCD). The shapes of the pT and y distributions of beauty quarks predicted by state-of-the-art perturbative QCD models are used to extrapolate an estimate of the b b ¯ pair cross section at midrapidity and in the total phase space. The total b b ¯ cross sections are found to be σbb ¯ = 541 ± 45 (stat.) ± 69 (syst.)−12+10 (extr.) μb and σbb ¯ = 218±37 (stat.)±31 (syst.)−9.1+8.2 (extr.) μb at s = 13 and 5.02 TeV, respectively. The value obtained from the combination of ALICE and LHCb measurements in pp collisions at s = 13 TeV is also provided. [Figure not available: see fulltext.] © 2022, The Author(s).
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| 100. |
- Acharya, S., et al.
(författare)
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Prompt D0, D+, and D*+ production in Pb–Pb collisions at √sNN = 5.02 TeV
- 2022
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2022:1
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Tidskriftsartikel (refereegranskat)abstract
- The production of prompt D0, D+, and D*+ mesons was measured at midrapidity (|y| < 0.5) in Pb–Pb collisions at the centre-of-mass energy per nucleon–nucleon pair sNN = 5.02 TeV with the ALICE detector at the LHC. The D mesons were reconstructed via their hadronic decay channels and their production yields were measured in central (0–10%) and semicentral (30–50%) collisions. The measurement was performed up to a transverse momentum (pT) of 36 or 50 GeV/c depending on the D meson species and the centrality interval. For the first time in Pb–Pb collisions at the LHC, the yield of D0 mesons was measured down to pT = 0, which allowed a model-independent determination of the pT-integrated yield per unit of rapidity (dN/dy). A maximum suppression by a factor 5 and 2.5 was observed with the nuclear modification factor (RAA) of prompt D mesons at pT = 6–8 GeV/c for the 0–10% and 30–50% centrality classes, respectively. The D-meson RAA is compared with that of charged pions, charged hadrons, and J/ψ mesons as well as with theoretical predictions. The analysis of the agreement between the measured RAA, elliptic (v2) and triangular (v3) flow, and the model predictions allowed us to constrain the charm spatial diffusion coefficient Ds. Furthermore the comparison of RAA and v2 with different implementations of the same models provides an important insight into the role of radiative energy loss as well as charm quark recombination in the hadronisation mechanisms. [Figure not available: see fulltext.] © 2022, The Author(s).
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