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- 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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| 3. |
- Acharya, S, et al.
(författare)
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Production of light (anti)nuclei in pp collisions at √s = 13 TeV
- 2022
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2022:1
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the production mechanism of light (anti)nuclei is one of the key challenges of nuclear physics and has important consequences for astrophysics, since it provides an input for indirect dark-matter searches in space. In this paper, the latest results about the production of light (anti)nuclei in pp collisions at s = 13 TeV are presented, focusing on the comparison with the predictions of coalescence and thermal models. For the first time, the coalescence parameters B2 for deuterons and B3 for helions are compared with parameter-free theoretical predictions that are directly constrained by the femtoscopic measurement of the source radius in the same event class. A fair description of the data with a Gaussian wave function is observed for both deuteron and helion, supporting the coalescence mechanism for the production of light (anti)nuclei in pp collisions. This method paves the way for future investigations of the internal structure of more complex nuclear clusters, including the hypertriton. [Figure not available: see fulltext.]. © 2022, The Author(s).
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| 4. |
- Vazquez Rueda, Omar
(författare)
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Study of the production of π, K and p in pp collisions at √s = 13 TeV as a function of the Transverse Spherocity and the Relative Transverse Activity
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- High-energy heavy-ion collisions allow the Quark-Gluon Plasma (QGP) production and study, a state of high-density QCD matter in which quarks and gluons are no longer confined inside hadrons for a very short time. Different observables reveal an enhanced production of strange hadrons, signatures of collective effects and opacity to jets due to the QGP formation. However, collective effects and strangeness enhancement are also observed in pp and p-Pb collisions (small systems) with high charged-particle multiplicity. These observations in small systems are very puzzling since the QGP is not expected to be formed since the small systems are considered too dilute and too short-lived.In this thesis, I present a study on the production of π, K and p in pp collisions at √s = 13 TeV using data recorded by the ALICE experiment. To investigate the origins of collective effects and strangeness enhancement, I measure the particle production as a function of the Relative Transverse Activity (RT) and the Transverse Spherocity (S0). In the RT analysis, particle production is measured in different topological regions (toward, away, and transverse) with respect to the leading charged track per event. The toward and away regions mainly contain the fragmentation products of the jet, while the Underlying Event dominates the transverse. The transverse momentum spectra and K/π and p/π ratios are measured as a function of RT = NT/⟨NT⟩, where NT is the charged-particle multiplicity in the transverse region. It is observed that the K/π and p/π ratios increase with increasing RT in the toward region, while little RT dependence is observed in the transverse. Models tuned to e+e- results describe the low-RT particle ratios qualitatively.The transverse spherocity is an event shape observable that can disentangle jet-like from isotropic topologies. I studied particle production in high-multiplicity events as a function of spherocity. I contrast the results obtained using a forward and a mid-pseudorapidity multiplicity estimator. The results show that the mid-pseudorapidity estimator combined with the spherocity selection allows selecting events with more significant variations in the average transverse momentum (⟨pT⟩) than the forward estimator. I present the pT spectra and particle ratios as a function of S0. Finally, all the data results are contrasted with microscopic models.
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