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Nuclear Theory·nucl-th

Wednesday·February 1, 2023

6 papers—3 primary·3 cross-listed

All6Primary3Cross-lists3
  1. 01

    [Submitted on 30 Jan 2023]

    Dense Nuclear Matter Equation of State from Heavy-Ion Collisions

    Agnieszka Sorensen🇺🇸 · Kshitij Agarwal🇩🇪 · Kyle W. Brown🇺🇸 · Zbigniew Chajęcki🇺🇸 · Paweł Danielewicz🇺🇸 · Christian Drischler🇺🇸 · Stefano Gandolfi🇺🇸 · Jeremy W. Holt🇺🇸 · Matthias Kaminski🇺🇸 · Che-Ming Ko🇺🇸 · Rohit Kumar🇺🇸 · Bao-An Li🇺🇸 and 124 other authors

    The nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS.

    Comments:
    White paper prepared for the 2023 Long Range Plan. v3: Updated version as published in Progress in Particle and Nuclear Physics. Note: the published version does not include the executive summary; in the updated arXiv version, the executive summary is included as an appendix. v4: Corrected list of authors
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.13253 [pdf]
    PPNP(2024)·280 citations
  2. 02

    [Submitted on 31 Jan 2023]

    Investigating the fission dynamics of the following neutron shell closed nuclei within a stochastic dynamical approach: 210Po, 212Rn, and 213Fr

    Divya Arora · P. Sugathan · A. Chatterjee

    Dissipative dynamics of nuclear fission is a well confirmed phenomenon described either by a Kramers-modified statistical model or by a dynamical model employing the Langevin equation. Though dynamical models as well as statistical models incorporating fission delay are found to explain the measured fission observables in many studies, it nonetheless shows conflicting results for shell closed nuclei in the mass region 200. Analysis of recent data for neutron shell closed nuclei in excitation energy range 4080 MeV failed to arrive at a satisfactory description of the data and attributed the mismatch to shell effects and/or entrance channel effects, without reaching a definite conclusion. In the present work we show that a well established stochastic dynamical code simultaneously reproduces the available data of pre-scission neutron multiplicities, fission and evaporation residue excitation functions for neutron shell closed nuclei Po and Rn and their isotopes Po and Rn without the need for including any extra shell or entrance channel effects. The calculations are performed by using a phenomenological universal friction form factor with no ad-hoc adjustment of model parameters. However, we note significant deviation, beyond experimental errors, in some cases of Fr isotopes.

    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2301.13461 [pdf]
    CPC(2023)·2 citations
  3. 03

    [Submitted on 31 Jan 2023]

    Identical Bands Around the Isobaric Rare Earth Even-Even Nuclei with the Mass Number A = 164

    M. A. Abdelsalam · H. A. Ghanim · M. Kotb · A. M. Khalaf

    Eight pairs of rare earth normally deformed nuclei around the isobaric nuclei with A = 164 and have identical values of F-spin have been studied. These pairs of identical bands cover 16 mass units and are classified. We suggested a theoretical collective rotational formula containing three parameters (CRF3) as an extended version of Bohr-Mottelson model to calculate the ground state positive parity excitation energies. Also, the sd-version of the interacting boson model (IBM) has been used to describe the nuclear shapes by using the intrinsic coherent-state. The optimized models parameters for each nucleus are adjusted by using a simulation search program to minimize the root mean square deviation between the theoretical calculation and experimental excitation energies. The best adopted model parameters of the CRF3 are used to calculate the rotational frequencies, the kinematic and dynamic moments of inertia and the evolution of with increasing hw are systematically analyzed. A smooth gradual increase in both moments of inertia was seen. The calculated results agree excellently with the experimental ones which give strong support to the suggested CRF3. The adopted IBM parameters are used to calculate the potential energy surfaces which describe the nuclear deformation. The correlation quantities which identify the IB are extracted, exhibit identical excitation energies and energy ratios in their ground state rotational bands.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2301.13503 [pdf]
    Phys.Atom.Nucl.(2023)·1 citation
  4. 04

    [Submitted on 30 Jan 2023] (cross-list from hep-ph)

    Extraction of neutron density distributions from high-statistics coherent elastic neutrino-nucleus scattering data

    D. Aristizabal Sierra🇨🇱

    Forthcoming fixed-target coherent elastic neutrino-nucleus scattering experiments aim at measurements with -scale detectors and substantially reduced systematic and statistical uncertainties. With such high quality data, the extraction of point-neutron distributions mean-square radii requires a better understanding of possible theoretical uncertainties. We quantify the impact of single-nucleon electromagnetic mean-square radii on the weak-charge form factor and compare results from weak-charge form factor parametrizations and weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors, including nucleon form factors -dependent terms up to order . We assess as well the differences arising from results derived using weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors and a model-independent approach based solely on the assumption of spherically symmetric nuclear ground state. We demonstrate the impact of the main effects by assuming pseudo-data from a one-tonne LAr detector and find that, among the effects and under the assumptions considered in this paper, weak-charge form factor parametrizations and weak-charge form factor decompositions in terms of elastic vector proton and neutron form factors enable the extraction of the point-neutron distribution mean-square radius with a accuracy. With a substantial reduction of the beam-related neutron and steady-state backgrounds a precision extraction seems feasible, using either of the two approaches.

    Comments:
    14 pages, 7 figures, 1 table. A few clarifications added. Matches version published in PLB
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2301.13249 [pdf]
    PLB(2023)·14 citations
  5. 05

    [Submitted on 31 Jan 2023] (cross-list from hep-ph)

    Perfect QCD -- a new Universal approach to soft QCD

    Peter Christiansen🇸🇪

    The ideas presented in this proceeding aims to be a first step towards a description of hadronic collisions where all soft processes are fundamentally strongly coupled and the same Universal strongly coupled physics drives both initial and final-state interactions. As it is not currently possible to derive such a picture from first principles, instead, an attempt to generalize the perfect liquid observation to a ``perfect QCD'' guiding principle is presented, focusing on implications for particle production in small systems. The first steps towards a microscopic model is taken by arguing that ``perfect QCD'' suggests that the screening in the initial state is so large that multi-parton interactions are of little or no importance. Instead, a target and projectile remnant is coherently excited and particle production is mainly driven by radiation in a qualitative similar manner as . Finally, some of the possible implications of this ``excited remnant model'' are presented. It is argued that the time ordering of soft and hard physics can explain the absence of jet quenching in small systems and that the coherence scale of the projectile and target provides insights into what small systems will exhibit flow.

    Comments:
    6 pages, 2 figures. Proceeding for WWND 2022
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2301.13467 [pdf]
    Rev.Mex.Fis.Suppl.(2022)·0 citations
  6. 06

    [Submitted on 31 Jan 2023] (cross-list from hep-ph)

    QCD equation of state at finite isospin density from the linear sigma model with quarks: The cold case

    Alejandro Ayala🇲🇽 · Aritra Bandyopadhyay🇧🇷 · Ricardo L. S. Farias🇧🇷 · Luis A. Hernández🇿🇦 · José Luis Hernández🇪🇸

    We use the two-flavor linear sigma model with quarks to study the phase structure of isospin asymmetric matter at zero temperature. The meson degrees of freedom provide the mean field chiral- and isospin-condensates on top of which we compute the effective potential accounting for constituent quark fluctuations at one-loop order. Using the renormalizability of the model, we absorb the ultraviolet divergences into suitable counter-terms that are added respecting the original structure of the theory. These counter-terms are determined from the stability conditions which require the effective potential to have minima in the condensates directions at the classical values, as well as the transition from the non-condensed to the condensed phase to be smooth as a function of the isospin chemical potential. We use the model to study the evolution of the condensates as well as the pressure, energy and isospin densities and the sound velocity as functions of the isospin chemical potential. The approach does a good average description up to isospin chemical potentials values not too large as compared to the vacuum pion mass.

    Comments:
    11 pages and 7 figures. Expanded discussion, references and graphs added, conclusions unchanged
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2301.13633 [pdf]
    PRD(2023)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE