| 1. |
- Acharya, S, et al.
(författare)
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Anisotropic flow of identified hadrons in Xe-Xe collisions at √sNN = 5.44 TeV
- 2021
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2021:10
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of elliptic (v2) and triangular (v3) flow coefficients of π±, K±, p+p ¯ , KS0, and Λ+Λ ¯ obtained with the scalar product method in Xe-Xe collisions at sNN = 5.44 TeV are presented. The results are obtained in the rapidity range |y| < 0.5 and reported as a function of transverse momentum, pT, for several collision centrality classes. The flow coefficients exhibit a particle mass dependence for pT< 3 GeV/c, while a grouping according to particle type (i.e., meson and baryon) is found at intermediate transverse momenta (3 < pT< 8 GeV/c). The magnitude of the baryon v2 is larger than that of mesons up to pT = 6 GeV/c. The centrality dependence of the shape evolution of the pT-differential v2 is studied for the various hadron species. The v2 coefficients of π±, K±, and p+p ¯ are reproduced by MUSIC hydrodynamic calculations coupled to a hadronic cascade model (UrQMD) for pT< 1 GeV/c. A comparison with vn measurements in the corresponding centrality intervals in Pb-Pb collisions at sNN = 5.02 TeV yields an enhanced v2 in central collisions and diminished value in semicentral collisions. [Figure not available: see fulltext.] © 2021, The Author(s).
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| 2. |
- Acharya, S, et al.
(författare)
-
(Anti-)deuteron production in pp collisions at √s=13TeV
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:9
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Tidskriftsartikel (refereegranskat)abstract
- The study of (anti-)deuteron production 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 (anti-)deuterons is studied as a function of the charged particle multiplicity in inelastic pp collisions at s=13 TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity (d Nch/ d η∼ 26) as measured in p–Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p–Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM). © 2020, The Author(s).
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| 3. |
- Acharya, S, et al.
(författare)
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Azimuthal correlations of prompt D mesons with charged particles in pp and p–Pb collisions at √sNN=5.02TeV
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:10
-
Tidskriftsartikel (refereegranskat)abstract
- The measurement of the azimuthal-correlation function of prompt D mesons with charged particles in pp collisions at s=5.02TeV and p–Pb collisions at sNN=5.02TeV with the ALICE detector at the LHC is reported. The D , D +, and D ∗ + mesons, together with their charge conjugates, were reconstructed at midrapidity in the transverse momentum interval 30.3GeV/c and pseudorapidity | η| < 0.8. The properties of the correlation peaks appearing in the near- and away-side regions (for Δ φ≈ 0 and Δ φ≈ π, respectively) were extracted via a fit to the azimuthal correlation functions. The shape of the correlation functions and the near- and away-side peak features are found to be consistent in pp and p–Pb collisions, showing no modifications due to nuclear effects within uncertainties. The results are compared with predictions from Monte Carlo simulations performed with the PYTHIA, POWHEG+PYTHIA, HERWIG, and EPOS 3 event generators. © 2020, The Author(s).
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| 4. |
- Acharya, S, et al.
(författare)
-
Centrality dependence of J/ψ and ψ(2S) production and nuclear modification in p-Pb collisions at √sNN = 8.16 TeV
- 2021
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2021
-
Tidskriftsartikel (refereegranskat)abstract
- The inclusive production of the J/ψ and ψ(2S) charmonium states is studied as a function of centrality in p-Pb collisions at a centre-of-mass energy per nucleon pair sNN = 8.16 TeV at the LHC. The measurement is performed in the dimuon decay channel with the ALICE apparatus in the centre-of-mass rapidity intervals −4.46 < ycms< −2.96 (Pb-going direction) and 2.03 < ycms< 3.53 (p-going direction), down to zero transverse momentum (pT). The J/ψ and ψ(2S) production cross sections are evaluated as a function of the collision centrality, estimated through the energy deposited in the zero degree calorimeter located in the Pb-going direction. The pT-differential J/ψ production cross section is measured at backward and forward rapidity for several centrality classes, together with the corresponding average 〈pT〉 and 〈pT2〉 values. The nuclear effects affecting the production of both charmonium states are studied using the nuclear modification factor. In the p-going direction, a suppression of the production of both charmonium states is observed, which seems to increase from peripheral to central collisions. In the Pb-going direction, however, the centrality dependence is different for the two states: the nuclear modification factor of the J/ψ increases from below unity in peripheral collisions to above unity in central collisions, while for the ψ(2S) it stays below or consistent with unity for all centralities with no significant centrality dependence. The results are compared with measurements in p-Pb collisions at sNN = 5.02 TeV and no significant dependence on the energy of the collision is observed. Finally, the results are compared with theoretical models implementing various nuclear matter effects. [Figure not available: see fulltext.] © 2021, The Author(s).
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| 5. |
- Acharya, S, et al.
(författare)
-
Charged-particle multiplicity fluctuations in Pb–Pb collisions at √sNN = 2.76 TeV
- 2021
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6052. ; 81:11
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of event-by-event fluctuations of charged-particle multiplicities in Pb–Pb collisions at sNN = 2.76 TeV using the ALICE detector at the CERN Large Hadron Collider (LHC) are presented in the pseudorapidity range | η| < 0.8 and transverse momentum 0.2 < pT< 2.0 GeV/c. The amplitude of the fluctuations is expressed in terms of the variance normalized by the mean of the multiplicity distribution. The η and pT dependences of the fluctuations and their evolution with respect to collision centrality are investigated. The multiplicity fluctuations tend to decrease from peripheral to central collisions. The results are compared to those obtained from HIJING and AMPT Monte Carlo event generators as well as to experimental data at lower collision energies. Additionally, the measured multiplicity fluctuations are discussed in the context of the isothermal compressibility of the high-density strongly-interacting system formed in central Pb–Pb collisions. © 2021, The Author(s).
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| 6. |
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| 7. |
- Acharya, S, et al.
(författare)
-
Coherent J / ψ and ψ ′ photoproduction at midrapidity in ultra-peripheral Pb–Pb collisions at √sNN=5.02 TeV
- 2021
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 81:8
-
Tidskriftsartikel (refereegranskat)abstract
- The coherent photoproduction of J/ψ and ψ′ mesons was measured in ultra-peripheral Pb–Pb collisions at a center-of-mass energy sNN−−−√ = 5.02 TeV with the ALICE detector. Charmonia are detected in the central rapidity region for events where the hadronic interactions are strongly suppressed. The J/ψ is reconstructed using the dilepton (l+l−) and proton–antiproton decay channels, while for the ψ′ the dilepton and the l+l−π+π− decay channels are studied. The analysis is based on an event sample corresponding to an integrated luminosity of about 233 μb−1. The results are compared with theoretical models for coherent J/ψ and ψ′ photoproduction. The coherent cross section is found to be in a good agreement with models incorporating moderate nuclear gluon shadowing of about 0.64 at a Bjorken-x of around 6×10−4, such as the EPS09 parametrization, however none of the models is able to fully describe the rapidity dependence of the coherent J/ψ cross section including ALICE measurements at forward rapidity. The ratio of ψ′ to J/ψ coherent photoproduction cross sections was also measured and found to be consistent with the one for photoproduction off protons.
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| 8. |
- Acharya, S, et al.
(författare)
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Coherent photoproduction of ρ 0 vector mesons in ultra-peripheral Pb-Pb collisions at √sNN = 5.02 TeV
- 2020
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2020:6
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Tidskriftsartikel (refereegranskat)abstract
- Cross sections for the coherent photoproduction of ρ0 vector mesons in ultra-peripheral Pb-Pb collisions at sNN = 5.02 TeV are reported. The measurements, which rely on the π+π− decay channel, are presented in three regions of rapidity covering the range |y| < 0.8. For each rapidity interval, cross sections are shown for different nuclear-breakup classes defined according to the presence of neutrons measured in the zero-degree calorimeters. The results are compared with predictions based on different models of nuclear shadowing. Finally, the observation of a coherently produced resonance-like structure with a mass around 1.7 GeV/c2 and a width of about 140 MeV/c2 is reported and compared with similar observations from other experiments. [Figure not available: see fulltext.] © 2020, The Author(s).
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| 9. |
- Acharya, S, et al.
(författare)
-
Constraining the Chiral Magnetic Effect with charge-dependent azimuthal correlations in Pb-Pb collisions at √sNN = 2.76 and 5.02 TeV
- 2020
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2020:9
-
Tidskriftsartikel (refereegranskat)abstract
- Systematic studies of charge-dependent two- and three-particle correlations in Pb-Pb collisions at sNN = 2.76 and 5.02 TeV used to probe the Chiral Magnetic Effect (CME) are presented. These measurements are performed for charged particles in the pseudorapidity (η) and transverse momentum (pT) ranges |η| < 0.8 and 0.2 < pT< 5 GeV/c. A significant charge-dependent signal that becomes more pronounced for peripheral collisions is reported for the CME-sensitive correlators γ1, 1 = 〈cos(φα + φβ − 2Ψ2)〉 and γ1, − 3 = 〈cos(φα − 3φβ + 2Ψ2)〉. The results are used to estimate the contribution of background effects, associated with local charge conservation coupled to anisotropic flow modulations, to measurements of the CME. A blast-wave parametrisation that incorporates local charge conservation tuned to reproduce the centrality dependent background effects is not able to fully describe the measured γ1,1. Finally, the charge and centrality dependence of mixed-harmonics three-particle correlations, of the form γ1, 2 = 〈cos(φα + 2φβ − 3Ψ3)〉, which are insensitive to the CME signal, verify again that background contributions dominate the measurement of γ1,1.
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| 10. |
- Acharya, S, et al.
(författare)
-
Dielectron production in proton-proton and proton-lead collisions at sNN =5.02 TeV
- 2020
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Ingår i: Physical Review C. - 2469-9985. ; 102:5
-
Tidskriftsartikel (refereegranskat)abstract
- The first measurements of dielectron production at midrapidity (|ηe|<0.8) in proton–proton and proton–lead collisions at √sNN=5.02TeV at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass mee and the pair transverse momentum pT,ee in the ranges mee<3.5 GeV/c2 and pT,ee<8 GeV/c, in both collision systems. In proton–proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at √s=7 and 13 TeV. The slope of the √s dependence of the three measurements is described by FONLL calculations. The dielectron cross section measured in proton–lead collisions is in agreement, within the current precision, with the expected dielectron production without any nuclear matter effects for e+e− pairs from open heavy-flavor hadron decays. For the first time at LHC energies, the dielectron production in proton–lead and proton–proton collisions are directly compared at the same √sNN via the dielectron nuclear modification factor RpPb. The measurements are compared to model calculations including cold nuclear matter effects, or additional sources of dielectrons from thermal radiation.
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| 11. |
- Acharya, S, et al.
(författare)
-
Elliptic and triangular flow of (anti)deuterons in Pb-Pb collisions at sNN =5.02 TeV
- 2020
-
Ingår i: Physical Review C. - 2469-9985. ; 102:5
-
Tidskriftsartikel (refereegranskat)abstract
- The measurements of the (anti)deuteron elliptic flow (v2) and the first measurements of triangular flow (v3) in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon collision sNN = 5.02 TeV are presented. A mass ordering at low transverse momentum (pT) is observed when comparing these measurements with those of other identified hadrons, as expected from relativistic hydrodynamics. The measured (anti)deuteron v2 lies between the predictions from the simple coalescence and blast-wave models, which provide a good description of the data only for more peripheral and for more central collisions, respectively. The mass number scaling, which is violated for v2, is approximately valid for the (anti)deuterons v3. The measured v2 and v3 are also compared with the predictions from a coalescence approach with phase-space distributions of nucleons generated by iebe-vishnu with ampt initial conditions coupled with urqmd, and from a dynamical model based on relativistic hydrodynamics coupled to the hadronic afterburner smash. The model predictions are consistent with the data within the uncertainties in midcentral collisions, while a deviation is observed in the most central collisions. © 2020 CERN.
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| 12. |
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| 13. |
- Acharya, S, et al.
(författare)
-
Energy dependence of ϕ meson production at forward rapidity in pp collisions at the LHC
- 2021
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 81:8
-
Tidskriftsartikel (refereegranskat)abstract
- The production of ϕ mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region 2.5 < y< 4. Measurements of the differential cross section d 2σ/ d yd pT are presented as a function of the transverse momentum (pT) at the center-of-mass energies s=5.02, 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at s=5.02 and 13 TeV are also studied in several rapidity intervals as a function of pT, and as a function of rapidity in three pT intervals. A hardening of the pT-differential cross section with the collision energy is observed, while, for a given energy, pT spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing pT. The new results, complementing the published measurements at s=2.76 and 7 TeV, allow one to establish the energy dependence of ϕ meson production and to compare the measured cross sections with phenomenological models. None of the considered models manages to describe the evolution of the cross section with pT and rapidity at all the energies. © 2021, The Author(s).
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| 14. |
- Acharya, S, et al.
(författare)
-
Evidence of rescattering effect in Pb–Pb collisions at the LHC through production of K(892)0⁎ and ϕ(1020) mesons
- 2020
-
Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 802
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of K(892)0⁎ and ϕ(1020) resonance production in Pb–Pb and pp collisions at sNN = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity (|y| < 0.5) via their hadronic decay channels and the transverse momentum (pT) distributions are obtained for various collision centrality classes up to pT = 20 GeV/c. The pT-integrated yield ratio K(892)0⁎/K in Pb–Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the ϕ(1020)/K ratio does not show any suppression. Furthermore, the measured K(892)0⁎/K ratio in central Pb–Pb collisions is significantly suppressed with respect to the expectations based on a thermal model calculation, while the ϕ(1020)/K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescattering of K(892)0⁎ decay products in the hadronic phase of the collisions. The K(892)0⁎/K yield ratios in Pb–Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out, which is found to be ∼ 4–7 fm/c for central collisions. The pT-differential ratios of K(892)0⁎/K, ϕ(1020)/K, K(892)0⁎/π, ϕ(1020)/π, p/K(892)0⁎ and p/ϕ(1020) are also presented for Pb–Pb and pp collisions at sNN = 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-pT phenomenon.
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| 15. |
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| 16. |
- Acharya, S, et al.
(författare)
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Experimental Evidence for an Attractive p-φ Interaction
- 2021
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Ingår i: Physical Review Letters. - 1079-7114. ; 127:17
-
Tidskriftsartikel (refereegranskat)abstract
- This Letter presents the first experimental evidence of the attractive strong interaction between a proton and a φ meson. The result is obtained from two-particle correlations of combined p-φ p¯-φ pairs measured in high-multiplicity pp collisions at s=13 TeV by the ALICE Collaboration. The spin-averaged scattering length and effective range of the p-φ interaction are extracted from the fully corrected correlation function employing the Lednický-Lyuboshits approach. In particular, the imaginary part of the scattering length vanishes within uncertainties, indicating that inelastic processes do not play a prominent role for the p-φ interaction. These data demonstrate that the interaction is dominated by elastic p-φ scattering. Furthermore, an analysis employing phenomenological Gaussian- and Yukawa-type potentials is conducted. Under the assumption of the latter, the N-φ coupling constant is found to be gN-φ=0.14±0.03(stat)±0.02(syst). This work provides valuable experimental input to accomplish a self-consistent description of the N-φ interaction, which is particularly relevant for the more fundamental studies on partial restoration of chiral symmetry in nuclear medium. © 2021 CERN.
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| 17. |
- Acharya, S, et al.
(författare)
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First measurement of the |t|-dependence of coherent J/ψ photonuclear production
- 2021
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 817
-
Tidskriftsartikel (refereegranskat)abstract
- The first measurement of the cross section for coherent J/ψ photoproduction as a function of |t|, the square of the momentum transferred between the incoming and outgoing target nucleus, is presented. The data were measured with the ALICE detector in ultra-peripheral Pb–Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02TeV with the J/ψ produced in the central rapidity region |y|<0.8, which corresponds to the small Bjorken-x range (0.3−1.4)×10−3. The measured |t|-dependence is not described by computations based only on the Pb nuclear form factor, while the photonuclear cross section is better reproduced by models including shadowing according to the leading-twist approximation, or gluon-saturation effects from the impact-parameter dependent Balitsky–Kovchegov equation. These new results are therefore a valid tool to constrain the relevant model parameters and to investigate the transverse gluonic structure at very low Bjorken-x. © 2021 The Author(s)
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| 18. |
- Acharya, S, et al.
(författare)
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First measurements of N-subjettiness in central Pb-Pb collisions at √sNN = 2.76 TeV
- 2021
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2021:9
-
Tidskriftsartikel (refereegranskat)abstract
- The ALICE Collaboration reports the first fully-corrected measurements of the N-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb-Pb collisions at centre-of-mass energies of s = 7 TeV and sNN = 2.76 TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, τ2/τ1, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of R = 0.4 and charged jet transverse momentum of 40 ≤ pT,jet ≤ 60 GeV/c, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the τ2/τ1 observable for track-based jets in Pb-Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of τ2/τ1, together with the splitting aperture angle ∆R, are also performed in pp collisions at s = 7 TeV for inclusive jets. These results are compared with PYTHIA calculations at s = 7 TeV, in order to validate the model as a vacuum reference for the Pb-Pb centre-of-mass energy. The PYTHIA references for τ2/τ1 are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb-Pb collisions compared to pp collisions. [Figure not available: see fulltext.] © 2021, The Author(s).
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| 19. |
- Acharya, S., et al.
(författare)
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First study of the two-body scattering involving charm hadrons
- 2022
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Ingår i: Physical Review D. - 2470-0010. ; 106:5
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the first measurement of the interaction between charm hadrons and nucleons. The two-particle momentum correlations of pD- and p¯D+ pairs are measured by the ALICE Collaboration in high-multiplicity pp collisions at s=13 TeV. The data are compatible with the Coulomb-only interaction hypothesis within (1.1-1.5)σ. The level of agreement slightly improves if an attractive nucleon (N)D¯ strong interaction is considered, in contrast to most model predictions which suggest an overall repulsive interaction. This measurement allows for the first time an estimation of the 68% confidence level interval for the isospin I=0 inverse scattering length of the ND¯ state f0,I=0-1 [-0.4,0.9] fm-1, assuming negligible interaction for the isospin I=1 channel. © 2022 CERN.
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| 20. |
- Acharya, S, et al.
(författare)
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Higher harmonic non-linear flow modes of charged hadrons in Pb-Pb collisions at √sNN = 5.02 TeV
- 2020
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2020:5
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Tidskriftsartikel (refereegranskat)abstract
- Anisotropic flow coefficients, vn, non-linear flow mode coefficients, χn,mk, and correlations among different symmetry planes, ρn,mk are measured in Pb-Pb collisions at sNN = 5.02 TeV. Results obtained with multi-particle correlations are reported for the transverse momentum interval 0.2 < pT< 5.0 GeV/c within the pseudorapidity interval 0.4 < |η| < 0.8 as a function of collision centrality. The vn coefficients and χn,mk and ρn,mk are presented up to the ninth and seventh harmonic order, respectively. Calculations suggest that the correlations measured in different symmetry planes and the non-linear flow mode coefficients are dependent on the shear and bulk viscosity to entropy ratios of the medium created in heavy-ion collisions. The comparison between these measurements and those at lower energies and calculations from hydrodynamic models places strong constraints on the initial conditions and transport properties of the system.
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| 21. |
- Acharya, S, et al.
(författare)
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Inclusive heavy-flavour production at central and forward rapidity in Xe–Xe collisions at sNN=5.44 TeV
- 2021
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 819
-
Tidskriftsartikel (refereegranskat)abstract
- The first measurements of the production of muons and electrons from heavy-flavour hadron decays in Xe–Xe collisions at sNN=5.44 TeV, using the ALICE detector at the LHC, are reported. The measurement of the nuclear modification factor RAA is performed as a function of transverse momentum pT in several centrality classes at forward rapidity (2.5
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| 22. |
- Acharya, S, et al.
(författare)
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Inclusive J / ψ production at midrapidity in pp collisions at √s=13 TeV
- 2021
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 81:12
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Tidskriftsartikel (refereegranskat)abstract
- We report on the inclusive J / ψ production cross section measured at the CERN Large Hadron Collider in proton–proton collisions at a center-of-mass energy s=13 TeV. The J / ψ mesons are reconstructed in the e +e - decay channel and the measurements are performed at midrapidity (| y| < 0.9) in the transverse-momentum interval 0 < pT< 40 GeV/c, using a minimum-bias data sample corresponding to an integrated luminosity Lint=32.2nb-1 and an Electromagnetic Calorimeter triggered data sample with Lint=8.3pb-1. The pT-integrated J / ψ production cross section at midrapidity, computed using the minimum-bias data sample, is dσ/dy|y=0=8.97±0.24(stat)±0.48(syst)±0.15(lumi)μb. An approximate logarithmic dependence with the collision energy is suggested by these results and available world data, in agreement with model predictions. The integrated and pT-differential measurements are compared with measurements in pp collisions at lower energies and with several recent phenomenological calculations based on the non-relativistic QCD and Color Evaporation models. © 2021, The Author(s).
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| 23. |
- Acharya, S, et al.
(författare)
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Investigation of the p–Σ0 interaction via femtoscopy in pp collisions
- 2020
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Ingår i: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 805
-
Tidskriftsartikel (refereegranskat)abstract
- This Letter presents the first direct investigation of the p–Σ0 interaction, using the femtoscopy technique in high-multiplicity pp collisions at s=13 TeV measured by the ALICE detector. The Σ0 is reconstructed via the decay channel to Λγ, and the subsequent decay of Λ to pπ−. The photon is detected via the conversion in material to e+e− pairs exploiting the capability of the ALICE detector to measure electrons at low transverse momenta. The measured p–Σ0 correlation indicates a shallow strong interaction. The comparison of the data to several theoretical predictions obtained employing the Correlation Analysis Tool using the Schrödinger Equation (CATS) and the Lednický–Lyuboshits approach shows that the current experimental precision does not yet allow to discriminate between different models, as it is the case for the available scattering and hypernuclei data. Nevertheless, the p–Σ0 correlation function is found to be sensitive to the strong interaction, and driven by the interplay of the different spin and isospin channels. This pioneering study demonstrates the feasibility of a femtoscopic measurement in the p–Σ0 channel and with the expected larger data samples in LHC Run 3 and Run 4, the p–Σ0 interaction will be constrained with high precision. © 2020 European Organization for Nuclear Research
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| 24. |
- Acharya, S, et al.
(författare)
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J/ψ elliptic and triangular flow in Pb-Pb collisions at √sNN = 5.02 TeV
- 2020
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2020:10
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Tidskriftsartikel (refereegranskat)abstract
- The inclusive J/ψ elliptic (v2) and triangular (v3) flow coefficients measured at forward rapidity (2.5 < y < 4) and the v2 measured at midrapidity (|y| < 0.9) in Pb-Pb collisions at sNN = 5.02 TeV using the ALICE detector at the LHC are reported. The entire Pb-Pb data sample collected during Run 2 is employed, amounting to an integrated luminosity of 750 μb−1 at forward rapidity and 93 μb−1 at midrapidity. The results are obtained using the scalar product method and are reported as a function of transverse momentum pT and collision centrality. At midrapidity, the J/ψ v2 is in agreement with the forward rapidity measurement. The centrality averaged results indicate a positive J/ψ v3 with a significance of more than 5σ at forward rapidity in the pT range 2 < pT< 5 GeV/c. The forward rapidity v2, v3, and v3/v2 results at low and intermediate pT (pT ≲ 8 GeV/c) exhibit a mass hierarchy when compared to pions and D mesons, while converging into a species-independent curve at higher pT. At low and intermediate pT, the results could be interpreted in terms of a later thermalization of charm quarks compared to light quarks, while at high pT, path-length dependent effects seem to dominate. The J/ψ v2 measurements are further compared to a microscopic transport model calculation. Using a simplified extension of the quark scaling approach involving both light and charm quark flow components, it is shown that the D-meson vn measurements can be described based on those for charged pions and J/ψ flow. [Figure not available: see fulltext.] © 2020, The Author(s).
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| 25. |
- Acharya, S, et al.
(författare)
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J/ψ production as a function of charged-particle multiplicity in p-Pb collisions at √sNN = 8.16 TeV
- 2020
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2020:9
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Tidskriftsartikel (refereegranskat)abstract
- Inclusive J/ψ yields and average transverse momenta in p-Pb collisions at a center-of-mass energy per nucleon pair sNN = 8.16 TeV are measured as a function of the charged-particle pseudorapidity density with ALICE. The J/ψ mesons are reconstructed at forward (2.03 < ycms< 3.53) and backward (−4.46 < ycms< −2.96) center-of-mass rapidity in their dimuon decay channel while the charged-particle pseudorapidity density is measured around midrapidity. The J/ψ yields at forward and backward rapidity normalized to their respective average values increase with the normalized charged-particle pseudorapidity density, the former showing a weaker increase than the latter. The normalized average transverse momenta at forward and backward rapidity manifest a steady increase from low to high charged-particle pseudorapidity density with a saturation beyond the average value. [Figure not available: see fulltext.] © 2020, The Author(s).
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