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Nuclear Theory·nucl-th

Tuesday·August 24, 2021

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 01

    [Submitted on 21 Aug 2021]

    Evidence of the triaxial structure of Xe at the Large Hadron Collider

    Benjamin Bally🇪🇸 · Michael Bender🇫🇷 · Giuliano Giacalone🇩🇪 · Vittorio Somà🇫🇷

    The interpretation of the emergent collective behaviour of atomic nuclei in terms of deformed intrinsic shapes [1] is at the heart of our understanding of the rich phenomenology of their structure, ranging from nuclear energy to astrophysical applications across a vast spectrum of energy scales. A new window onto the deformation of nuclei has been recently opened with the realization that nuclear collision experiments performed at high-energy colliders, such as the CERN Large Hadron Collider (LHC), enable experimenters to identify the relative orientation of the colliding ions in a way that magnifies the manifestations of their intrinsic deformation [2]. Here we apply this technique to LHC data on collisions of Xe nuclei [3-5] to exhibit the first evidence of non-axiality in the ground state of ions collided at high energy. We predict that the low-energy structure of Xe is triaxial (a spheroid with three unequal axes), and show that such deformation can be determined from high-energy data. This result demonstrates the unique capabilities of precision collider machines such as the LHC as new means to perform imaging of the collective structure of atomic nuclei.

    Comments:
    8 pages; 4 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2108.09578 [pdf]
    PRL(2022)·105 citations
  2. 02

    [Submitted on 22 Aug 2021]

    Exploring the string shoving model in PYTHIA8 for collective behaviors in collisions

    Junlee Kim🇰🇷 · Eun-Joo Kim🇰🇷 · SuJeong Ji🇰🇷 · SangHoon Lim🇰🇷

    Two-particle correlations have been used to study property of a produced medium called Quark-Gluon Plasma (QGP) in relativistic heavy-ion collisions, and a long-range correlation among produced particles has been considered as a strong evidence of strongly interacting QGP. Strikingly, clear long-range correlations have been also observed in small collision systems like and + at a wide range of collision energies. A model introducing a repulsive force between flux tubes called string shoving can qualitatively describe the long-range near-side correlations in high multiplicity collisions. This model implemented in the PYTHIA Monte Carlo event generator allows us to perform detailed study. In this work, a full data analysis to calculate associated yields and flow coefficients is performed with PYTHIA events, and the results are compared with experimental results. We find that the string shoving model overestimates long-range near-side correlations particularly in low multiplicity events. We also introduce a method to subtract such overestimated correlations in low multiplicity to have a more relevant comparison with the data.

    Comments:
    12 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2108.09686 [pdf]
    J.Korean Phys.Soc.(2021)·9 citations
  3. 03

    [Submitted on 22 Aug 2021]

    Restoring Broken Symmetries for Nuclei and Reaction Fragments

    Aurel Bulgac

    In typical microscopic approaches, particularly when pairing correlations are present, nuclei and nuclear fragments do not have well defined quantum numbers and symmetries should be restored. I present here a formalism for the simultaneous projection of total particle numbers of a nucleus, particle number of reaction fragments, and of the reaction fragment intrinsic spins and of their correlation, and also for their symmetry restored densities and total energies. These new formulas for the symmetry restored quantities, are free of any singularities, unlike those in the previously introduced prescriptions.

    Comments:
    10 pages, published version, a number of corrections comlared to intial version
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2108.09846 [pdf]
    PRC(2021)·9 citations
  4. 04

    [Submitted on 23 Aug 2021]

    Recent progress on few-body hypernuclei

    Avraham Gal🇮🇱

    Few-body hypernuclei provide valuable information towards understanding strange matter. Recent experimental progress by the STAR Collaboration at the RHIC facility and by the ALICE Collaboration at the LHC has been matched by theoretical progress reviewed here: (i) lifetimes of the hypertriton H, n if particle-stable, H and He and their charge symmetry breaking, and (ii) the onset of hypernuclear binding.

    Comments:
    Invited talk at the 19th International Conference on Strangeness in Quark Matter (SQM 2021), online from BNL Upton NY USA, May 2021. Submitted to EPJ Web of Conferences. v2: Ref.[30] added, errors corrected. v3: updated slightly beyond published version
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2108.10179 [pdf]
    EPJ Web Conf.(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE