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Nuclear Theory·nucl-th

Friday·March 17, 2023

4 papers—3 primary·1 cross-listed

All4Primary3Cross-lists1
  1. 01

    [Submitted on 16 Mar 2023]

    Classification of pairing phase transition in the hot nucleus

    Yuhang Gao · Yanlong Lin · Lang Liu

    The hot nucleus is investigated using covariant density functional theory, where the shell-model-like approach treats the pairing correlation. Lee-Yang's theorem is applied to classify the pairing phase transition by analyzing the distribution of zeros of the partition function in the complex temperature plane. The distribution of zeros of the partition function converges with increasing particle numbers and illustrates the characteristics of the phase transition. In our calculations, we determine the first order of the phase transition near the critical temperature. Different seniority states show the pairing phase transition from a superfluid to a normal phase, ranging from fully paired states to completely unpaired states.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2303.09039 [pdf]
    IJMPE(2023)·4 citations
  2. 02

    [Submitted on 16 Mar 2023]

    Calculation of Dynamical Response Functions Using a Bound-state Method

    Niels R. Walet · Jagjit Singh · Johannes Kirscher · Michael C. Birse · Harald W. Griesshammer · Judith A. McGovern

    We investigate a method to extract response functions (dynamical polarisabilities) directly from a bound-state approach applied to calculations of perturbation-induced reactions. The use of a square-integrable basis leads to a response in the form of a sum of functions. We integrate this over energy and fit a smooth function to the resulting stepwise-continuous one. Its derivative gives the final approximation to the physical response function. We show that the method reproduces analytical results where known, and analyse the details for a variety of models. We apply it to some simple models, using the Stochastic Variational Method as the numerical method. Although we find that this approach, and other numerical techniques, have some difficulties with the threshold behaviour in coupled-channel problems with multiple thresholds, its stochastic nature allows us to extract robust results even for such cases.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2303.09361 [pdf]
    Few Body Syst.(2023)·4 citations
  3. 03

    [Submitted on 16 Mar 2023]

    Hydrodynamic Attractors in Ultrarelativistic Nuclear Collisions

    Jakub Jankowski🇵🇱 · Michał Spaliński🇵🇱

    One of the many physical questions that have emerged from studies of heavy-ion collisions at RHIC and the LHC concerns the validity of hydrodynamic modelling at the very early stages, when the Quark-Gluon Plasma system produced is still far from isotropy. In this article we review the idea of far-from-equilibrium hydrodynamic attractors as a way to understand how the complexity of initial states of nuclear matter is reduced so that a hydrodynamic description can be effective.

    Comments:
    The licence has been changed to CC-BY 4.0; the paper itself is unchanged
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2303.09414 [pdf]
    PPNP(2023)·50 citations
  4. 04

    [Submitted on 16 Mar 2023] (cross-list from nucl-ex)

    Nuclear neutron radius and weak mixing angle measurements from latest COHERENT CsI and atomic parity violation Cs data

    M. Atzori Corona🇮🇹 · M. Cadeddu🇮🇹 · N. Cargioli🇮🇹 · F. Dordei🇮🇹 · C. Giunti🇮🇹 · G. Masia🇮🇹

    The COHERENT collaboration observed coherent elastic neutrino nucleus scattering using a 14.6 kg cesium-iodide (CsI) detector in 2017 and recently published the updated results before decommissioning the detector. Here, we present the legacy determination of the weak mixing angle and of the average neutron rms radius of and obtained with the full CsI dataset, also exploiting the combination with the atomic parity violation (APV) experimental result, that allows us to achieve a precision as low as 4.5% and to disentangle the contributions of the and nuclei. Interestingly, we show that the COHERENT CsI data show a 6 evidence of the nuclear structure suppression of the full coherence. Moreover, we derive a data-driven APV+COHERENT measurement of the low-energy weak mixing angle with a percent uncertainty, independent of the value of the average neutron rms radius of and , that is allowed to vary freely in the fit. Additionally, we extensively discuss the impact of using two different determinations of the theoretical parity non-conserving amplitude in the APV fit. Our findings show that the particular choice can make a significant difference, up to 6.5% on (Cs) and 11% on the weak mixing angle. Finally, in light of the recent announcement of a future deployment of a 10 kg and a 700 kg cryogenic CsI detectors, we provide future prospects for these measurements, comparing them with other competitive experiments that are foreseen in the near future.

    Comments:
    21 pages, 10 figures, matches journal version
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2303.09360 [pdf]
    EPJC(2023)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE