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Nuclear Theory·nucl-th

Monday·April 18, 2022

6 papers—5 primary·1 cross-listed

All6Primary5Cross-lists1
  1. 01

    [Submitted on 14 Apr 2022]

    Cumulants of conserved charges in hydrodynamic simulations

    Renan Hirayama🇩🇪 · Frederique Grassi🇧🇷 · Willian Matioli Serenone🇧🇷 · Jean-Yves Ollitrault🇫🇷

    We introduce a fast and simple method of computing cumulants of net-proton or net-charge fluctuations in event-by-event hydrodynamic simulations of heavy-ion collisions. One evaluates the mean numbers of particles in every hydrodynamic event. Cumulants are then expressed as a function of these mean numbers. We implement the corrections due to global conservation laws. The method is tested using ideal hydrodynamic simulations of Au+Au collisions at AGeV with the NeXSPheRIO code. Results are in good agreement with experimental data on net-proton and net-charge fluctuations by the STAR collaboration.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    2204.07181 [pdf]
    PRC(2023)·5 citations
  2. 02

    [Submitted on 14 Apr 2022]

    Peeling away neutron skin in ultracentral collisions of relativistic nuclei

    Nikita Kozyrev (1 and 2) · Aleksandr Svetlichnyi (1 and 2) · Roman Nepeivoda (1 and 2) · Igor Pshenichnov (1 and 2) ((1) Moscow Institute of Physics and Technology, Dolgoprudny, Russia, (2) Institute for Nuclear Research, Russian Academy of Sciences, Moscow, Russia)

    In heavy nuclei the ratio between local densities of neutrons and protons increases towards the nuclear periphery. The excess of neutrons is known as the neutron skin (NS) with a subtle difference (~fm) between the r.m.s radii of the distributions of neutrons and protons. We show that the presence of NS in Pb leads to extra spectator neutrons in ultracentral Pb--Pb collisions at the CERN SPS and LHC. The yields of spectator neutrons and protons were calculated within a new version of Abrasion-Ablation Monte Carlo for Colliders model (AAMCC-MST) taking into account NS and pre-equilibrium clustering of spectator matter. While the average numbers of spectator neutrons and protons in ultracentral collisions vary insignificantly, the cross sections of emission of certain numbers of spectator neutrons in events with 0,1,...5 spectator protons are changed by 50--250\%, depending on the thickness of NS. These cross sections are less sensitive to other parameters in calculations, and their measurements in the ALICE experiment at the LHC will make it possible to restrict the existing variety of neutron density parameterizations in Pb.

    Comments:
    23 pages, 14 figures, 5 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2204.07189 [pdf]
    EPJA(2022)·9 citations
  3. 03

    [Submitted on 15 Apr 2022]

    Deformed in-medium similarity renormalization group

    Q. Yuan · S. Q. Fan · B. S. Hu · J. G. Li · S. Zhang · S. M. Wang · Z. H. Sun · Y. Z. Ma · F. R. Xu

    We have developed an {\it ab initio} deformed in-medium similarity renormalization group (IMSRG) for open-shell nuclei. This is a single-reference IMSRG in deformed Hartree-Fock (HF) basis. Deformed wave functions are more efficient in describing deformed nuclei. The broken spherical symmetry needs to be restored by angular momentum projection, which is computational expensive. The angular momentum mainly capture the static correlations and can be estimated by the projection of the HF state. In this work, we do deformed IMSRG calculation and add the correlation energy from projected HF as a leading order approximation. As the test ground, we have calculated the deformed isotopes with the optimized chiral interaction NNLO. The results are benchmarked with the no-core shell model and valence space IMSRG calculations. Then we systematically investigated the ground-state energies and charge radii of even-even isotopes from light beryllium to medium-mass magnesium. The calculated energies are extrapolated to infinite basis space by an exponential form, and compared with the extrapolated valence-space IMSRG results and experimental data available.

    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2204.07301 [pdf]
    PRC(2022)·31 citations
  4. 04

    [Submitted on 15 Apr 2022]

    Visualization of nuclear many-body correlations with the most probable configuration of nucleons

    Moemi Matsumoto · Yusuke Tanimura

    A method to visualize many-body correlations using the information of the full wave function is presented. The set of nucleon coordinates which maximizes the square of the wave function, that is, the most probable spatial configuration of nucleons, is visualized. The method is applied to Hartree-Fock (HF) and HF+BCS wave functions of - and -shell even-even nuclei to analyze the many-body correlations in those systems. It is found that there are -cluster-like four-body correlations already at the HF level in some of the nuclei. The effects of pairing on the most probable configuration are also investigated. The method is useful to analyze the nuclear many-body correlations, and it suggests a new viewpoint to microscopic nuclear wave functions.

    Comments:
    12 pages, 11 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2204.07355 [pdf]
    PRC(2022)·5 citations
  5. 05

    [Submitted on 15 Apr 2022]

    Nuclear matter calculations with the phenomenological three-nucleon interaction

    H. Moeini · G.H. Bordbar

    Employing the concept of three-body radial distribution function and using the two-body correlation functions, calculated based on the lowest order constrained variational method, we investigated the effect of the three-body force (TBF) on the nuclear matter properties, for Argonne and Urbana potentials. As such, the results for nuclear matter density, incompressibility, energy per nucleon, and symmetry energy are presented at the saturation point. The inclusion of a phenomenological TBF resulted in closer values of the saturation density, incompressibility, and symmetry energy to the empirical ones for the symmetric nuclear matter. This is especially the case for the Urbana potential. In addition, an empirically-verified parabolic approximation of the interaction energy was utilized to perform an approximate study of the nuclear matter with neutron excess. Hence, at densities higher than about 0.3~fm and for proton-to-neutron density ratios close to the symmetric nuclear matter, the inclusion of TBF resulted in an extra attraction for the Argonne as compared to the Urbana potential.

    Comments:
    20 pages, 6 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2204.07468 [pdf]
    NPA(2022)·4 citations
  6. 06

    [Submitted on 15 Apr 2022] (cross-list from hep-ph)

    Neutral-Current Electroweak Physics and SMEFT Studies at the EIC

    Radja Boughezal🇺🇸 · Alexander Emmert🇺🇸 · Tyler Kutz🇺🇸 · Sonny Mantry🇺🇸 · Michael Nycz🇺🇸 · Frank Petriello🇺🇸 · Kağan Şimşek🇺🇸 · Daniel Wiegand🇺🇸 · Xiaochao Zheng🇺🇸

    We study the potential for precision electroweak (EW) measurements and beyond-the-Standard Model (BSM) searches using cross-section asymmetries in neutral-current (NC) deep inelastic scattering at the electron-ion collider (EIC). Our analysis uses a complete and realistic accounting of systematic errors from both theory and experiment and considers the potential of both proton and deuteron beams for a wide range of energies and luminosities. We also consider what can be learned from a possible future positron beam and a potential ten-fold luminosity upgrade of the EIC beyond its initial decade of running. We use the SM effective field theory (SMEFT) framework to parameterize BSM effects and focus on semi-leptonic four-fermion operators, whereas for our precision EW study, we determine how well the EIC can measure the weak mixing angle. New features of our study include the use of an up-to-date detector design of EIC Comprehensive Chromodynamics Experiment (ECCE) and accurate running conditions of the EIC, the simultaneous fitting of beam polarization uncertainties and Wilson coefficients to improve the sensitivity to SMEFT operators, and the inclusion of the weak mixing angle running in our fit template. We find that the EIC can probe BSM operators at scales competitive with and in many cases exceeding LHC Drell-Yan bounds while simultaneously not suffering from degeneracies between Wilson coefficients.

    Comments:
    67 pages, 66 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
    arXiv:
    2204.07557 [pdf]
    PRD(2022)·46 citations

Affiliations

first authorsco-authorsvia INSPIRE