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Nuclear Theory·nucl-th

Wednesday·May 19, 2021

6 papers—2 primary·4 cross-listed

All6Primary2Cross-lists4
  1. 01

    [Submitted on 17 May 2021]

    -like quartetting in the excited states of proton-neutron pairing Hamiltonians

    M. Sambataro🇮🇹 · N. Sandulescu🇷🇴

    Previous studies have shown that the ground state of systems of nucleons composed by an equal number of protons and neutrons interacting via proton-neutron pairing forces can be described accurately by a condensate of -like quartets. Here we extend these studies to the low-lowing excited states of these systems and show that these states can be accurately described by breaking a quartet from the ground state condensate and replacing it with an "excited" quartet. This approach, which is analogous to the one-broken-pair approximation employed for like-particle pairing, is analysed for various isovector and isovector-isoscalar pairing

    Comments:
    14 pages, 4 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2105.08136 [pdf]
    PLB(2021)·10 citations
  2. 02

    [Submitted on 18 May 2021]

    Constructing approximate shell-model wavefunctions by eigenvector continuation

    Sota Yoshida🇯🇵 · Noritaka Shimizu🇯🇵

    Shell-model calculations play a key role in elucidating various properties of nuclei. In general, those studies require a huge number of calculations to be repeated for parameter calibration and quantifying uncertainties. To reduce the computational burden, we propose a new workflow of shell-model calculations using a method called eigenvector continuation (EC). It enables us to efficiently approximate the eigenpairs under a given Hamiltonian by previously sampled eigenvectors. We demonstrate the validity of EC as an emulator of the valence shell-model, including first application of EC to electromagnetic transition matrix elements. Furthermore, we propose a new usage of EC: preprocessing, in which we start the Lanczos iterations from the approximate eigenvectors, and demonstrate that this can accelerate subsequent research cycles. With the aid of the EC, the eigenvectors obtained during the parameter optimization are not necessarily to be discarded, even if their eigenvalues are far from the experimental data. Those eigenvectors can become accumulated knowledge.

    Comments:
    18 pages, title changed from v1, accepted for publication in PTEP
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2105.08256 [pdf]
    PTEP(2022)·33 citations
  3. 03

    [Submitted on 18 May 2021] (cross-list from hep-ph)

    Helicity polarization in relativistic heavy ion collisions

    Jian-Hua Gao🇨🇳

    We discuss the helicity polarization which can be locally induced from both vorticity and helicity charge in non-central heavy ion collisions. Helicity charge redistribution can be generated in viscous fluid and contributes to azimuthal asymmetry of the polarization along global angular momentum or beam momentum. We also discuss on detecting the initial net helicity charge from topological charge fluctuation or initial color longitudinal field by the helicity polarization correlation of two hyperons and the helicity alignment of vector mesons in central heavy ion collisions.

    Comments:
    5 pages, no figures, some typos corrected, more references added, averaged spin alignment with elliptic flow added
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2105.08293 [pdf]
    PRD(2021)·53 citations
  4. 04

    [Submitted on 18 May 2021] (cross-list from hep-ph)

    Impact parameter dependence of color charge correlations in the proton

    Adrian Dumitru🇺🇸 · Heikki Mäntysaari🇫🇮 · Risto Paatelainen🇫🇮

    The impact parameter dependence of color charge correlators in the proton is obtained from the light front formalism in light cone gauge. We include NLO corrections due to the Fock state via light-cone perturbation theory. Near the center of the proton, the -dependence of the correlations is very different from a "transverse profile function". The resulting -dependence of exclusive photoproduction transitions from exponential to power law at GeV. This prediction could be tested at upcoming DIS facilities or in nucleus-proton ultraperipheral collisions (UPCs).

    Comments:
    contribution to the proceedings of DIS 2021, to be submitted to SciPost Proceedings
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2105.08503 [pdf]
    SciPost Phys.Proc.(2022)·4 citations
  5. 05

    [Submitted on 18 May 2021] (cross-list from hep-th)

    Second order equilibrium transport in strongly coupled supersymmetric Yang-Mills plasma via holography

    Sebastian Grieninger🇪🇸 · Ashish Shukla🇨🇦

    A relativistic fluid in 3+1 dimensions with a global symmetry admits nine independent static susceptibilities at the second order in the hydrodynamic derivative expansion, which capture the response of the fluid in thermal equilibrium to the presence of external time-independent sources. Of these, seven are time-reversal invariant and can be obtained from Kubo formulas involving equilibrium two-point functions of the energy-momentum tensor and the current. Making use of the gauge/gravity duality along with the aforementioned Kubo formulas, we compute all seven invariant second order susceptibilities for the supersymmetric Yang-Mills plasma in the limit of large and at strong 't-Hooft coupling . In particular, we consider the plasma to be charged under a subgroup of the global R-symmetry of the theory. We present analytic expressions for three of the seven invariant susceptibilities, while the remaining four are computed numerically. The dual gravitational description for the charged plasma in thermal equilibrium in the absence of background electric and magnetic fields is provided by the asymptotically AdS Reissner-Nordström black brane geometry. The susceptibilities are extracted by studying perturbations to the bulk geometry as well as to the bulk gauge field. We also present an estimate of the second order transport coefficient , which determines the response of the fluid to the presence of background curvature, for QCD, and compare it with previous determinations made using different techniques.

    Comments:
    v2: Chern-Simons term included in the bulk description. Several presentation improvements and added clarifications. Multiple additional references
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2105.08673 [pdf]
    JHEP(2021)·13 citations
  6. 06

    [Submitted on 18 May 2021] (cross-list from astro-ph.HE)

    Nuclear-Physics Multi-Messenger Astrophysics Constraints on the Neutron-Star Equation of State: Adding NICER's PSR J0740+6620 Measurement

    Peter T. H. Pang · Ingo Tews · Michael W. Coughlin · Mattia Bulla · Chris Van Den Broeck · Tim Dietrich

    In the past few years, new observations of neutron stars and neutron-star mergers have provided a wealth of data that allow one to constrain the equation of state of nuclear matter at densities above nuclear saturation density. However, most observations were based on neutron stars with masses of about 1.4 solar masses, probing densities up to 3-4 times the nuclear saturation density. Even higher densities are probed inside massive neutron stars such as PSR J0740+6620. Very recently, new radio observations provided an update to the mass estimate for PSR J0740+6620 and X-ray observations by the NICER and XMM telescopes constrained its radius. Based on these new measurements, we revisit our previous nuclear-physics multi-messenger astrophysics constraints and derive updated constraints on the equation of state describing the neutron-star interior. By combining astrophysical observations of two radio pulsars, two NICER measurements, the two gravitational-wave detections GW170817 and GW190425, detailed modeling of the kilonova AT2017gfo, as well as the gamma-ray burst GRB170817A, we are able to estimate the radius of a typical 1.4-solar mass neutron star to be at confidence. Our analysis allows us to revisit the upper bound on the maximum mass of neutron stars and disfavors the presence of a strong first-order phase transition from nuclear matter to exotic forms of matter, such as quark matter, inside neutron stars.

    Comments:
    13 pages, 5 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2105.08688 [pdf]
    ApJ(2021)·181 citations

Affiliations

first authorsco-authorsvia INSPIRE