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- Abdulameer, N.J., et al.
(author)
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Improving constraints on gluon spin-momentum correlations in transversely polarized protons via midrapidity open-heavy-flavor electrons in p ↑+p collisions at s =200 GeV
- 2023
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In: Physical Review D. - 2470-0010. ; 107:5
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Journal article (peer-reviewed)abstract
- Polarized proton-proton collisions provide leading-order access to gluons, presenting an opportunity to constrain gluon spin-momentum correlations within transversely polarized protons and enhance our understanding of the three-dimensional structure of the proton. Midrapidity open-heavy-flavor production at s=200 GeV is dominated by gluon-gluon fusion, providing heightened sensitivity to gluon dynamics relative to other production channels. Transverse single-spin asymmetries of positrons and electrons from heavy-flavor hadron decays are measured at midrapidity using the PHENIX detector at the Relativistic Heavy Ion Collider. These charge-separated measurements are sensitive to gluon correlators that can in principle be related to gluon orbital angular momentum via model calculations. Explicit constraints on gluon correlators are extracted for two separate models, one of which had not been constrained previously. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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. Funded by SCOAP3.
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| 7. |
- Acharya, S., et al.
(author)
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Accessing the strong interaction between Λ baryons and charged kaons with the femtoscopy technique at the LHC
- 2023
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - 0370-2693. ; 845
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Journal article (peer-reviewed)abstract
- The interaction between Λ baryons and kaons/antikaons is a crucial ingredient for the strangeness S=0 and S=−2 sector of the meson–baryon interaction at low energies. In particular, the ΛK‾ might help in understanding the origin of states such as the Ξ(1620), whose nature and properties are still under debate. Experimental data on Λ–K and Λ–K‾ systems are scarce, leading to large uncertainties and tension between the available theoretical predictions constrained by such data. In this Letter we present the measurements of Λ–K⊕+Λ‾–K− and Λ–K⊕−Λ‾–K+ correlations obtained in the high-multiplicity triggered data sample in pp collisions at s=13 TeV recorded by ALICE at the LHC. The correlation function for both pairs is modeled using the Lednický–Lyuboshits analytical formula and the corresponding scattering parameters are extracted. The Λ–K⊕−Λ‾–K+ correlations show the presence of several structures at relative momenta k⁎ above 200 MeV/c, compatible with the Ω baryon, the Ξ(1690), and Ξ(1820) resonances decaying into Λ–K− pairs. The low k⁎ region in the Λ–K⊕−Λ‾–K+ also exhibits the presence of the Ξ(1620) state, expected to strongly couple to the measured pair. The presented data allow to access the ΛK+ and ΛK− strong interaction with an unprecedented precision and deliver the first experimental observation of the Ξ(1620) decaying into ΛK−. © 2023 The Author(s)
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- Acharya, S., et al.
(author)
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Anisotropic flow and flow fluctuations of identified hadrons in Pb–Pb collisions at √sNN = 5.02 TeV
- 2023
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In: Journal of High Energy Physics. - 1029-8479. ; 2023:5
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Journal article (peer-reviewed)abstract
- The first measurements of elliptic flow of π ±, K ±, p + p ¯ , KS0 , Λ + Λ ¯ , ϕ, Ξ −+ Ξ ¯ + , and Ω −+ Ω ¯ + using multiparticle cumulants in Pb–Pb collisions at sNN = 5.02 TeV are resented. Results obtained with two- (v 2{2}) and four-particle cumulants (v 2{4}) are shown as a function of transverse momentum, p T, for various collision centrality intervals. Combining the data for both v 2{2} and v 2{4} also allows us to report the first measurements of the mean elliptic flow, elliptic flow fluctuations, and relative elliptic flow fluctuations for various hadron species. These observables probe the event-by-event eccentricity fluctuations in the initial state and the contributions from the dynamic evolution of the expanding quark–gluon plasma. The characteristic features observed in previous p T-differential anisotropic flow measurements for identified hadrons with two-particle correlations, namely the mass ordering at low p T and the approximate scaling with the number of constituent quarks at intermediate p T, are similarly present in the four-particle correlations and the combinations of v 2{2} and v 2{4}. In addition, a particle species dependence of flow fluctuations is observed that could indicate a significant contribution from final state hadronic interactions. The comparison between experimental measurements and CoLBT model calculations, which combine the various physics processes of hydrodynamics, quark coalescence, and jet fragmentation, illustrates their importance over a wide p T range. [Figure not available: see fulltext.]. © 2023, The Author(s).
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- Acharya, S., et al.
(author)
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Azimuthal correlations of heavy-flavor hadron decay electrons with charged particles in pp and p–Pb collisions at √sNN = 5.02 TeV
- 2023
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In: European Physical Journal C. - 1434-6044. ; 83:8
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Journal article (peer-reviewed)abstract
- The azimuthal (Δ φ) correlation distributions between heavy-flavor decay electrons and associated charged particles are measured in pp and p–Pb collisions at sNN=5.02 TeV. Results are reported for electrons with transverse momentum 4 < pT< 16 GeV / c and pseudorapidity | η| < 0.6 . The associated charged particles are selected with transverse momentum 1 < pT< 7 GeV / c , and relative pseudorapidity separation with the leading electron | Δ η| < 1 . The correlation measurements are performed to study and characterize the fragmentation and hadronization of heavy quarks. The correlation structures are fitted with a constant and two von Mises functions to obtain the baseline and the near- and away-side peaks, respectively. The results from p–Pb collisions are compared with those from pp collisions to study the effects of cold nuclear matter. In the measured trigger electron and associated particle kinematic regions, the two collision systems give consistent results. The Δ φ distribution and the peak observables in pp and p–Pb collisions are compared with calculations from various Monte Carlo event generators. © 2023, The Author(s).
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- Acharya, S., et al.
(author)
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Closing in on critical net-baryon fluctuations at LHC energies: Cumulants up to third order in Pb–Pb collisions
- 2023
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In: Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 844
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Journal article (peer-reviewed)abstract
- Fluctuation measurements are important sources of information on the mechanism of particle production at LHC energies. This article reports the first experimental results on third-order cumulants of the net-proton distributions in Pb–Pb collisions at a center-of-mass energy sNN=5.02 TeV recorded by the ALICE detector. The results on the second-order cumulants of net-proton distributions at sNN=2.76 and 5.02 TeV are also discussed in view of effects due to the global and local baryon number conservation. The results demonstrate the presence of long-range rapidity correlations between protons and antiprotons. Such correlations originate from the early phase of the collision. The experimental results are compared with HIJING and EPOS model calculations, and the dependence of the fluctuation measurements on the phase-space coverage is examined in the context of lattice quantum chromodynamics (LQCD) and hadron resonance gas (HRG) model estimations. The measured third-order cumulants are consistent with zero within experimental uncertainties of about 4% and are described well by LQCD and HRG predictions. © 2022 The Author
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