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Nuclear Theory·nucl-th

Friday·March 22, 2019

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 21 Mar 2019]

    Embedding nuclear physics inside the unitary window

    Mario Gattobigio🇫🇷 · Alejandro Kievsky🇮🇹 · Michele Viviani🇮🇹

    The large values of the singlet and triplet scattering lengths locate the two-nucleon system close to the unitary limit, the limit in which these two values diverge. As a consequence, the system shows a continuous scale invariance which strongly constrains the values of the observables, a well-known fact already noticed a long time ago. The three-nucleon system shows a discrete scale invariance that can be observed by correlations of the triton binding energy with other observables as the doublet nucleon-deuteron scattering length or the alpha-particle binding energy. The low-energy dynamics of these systems is universal; it does not depend on the details of the particular way in which the nucleons interact. Instead, it depends on a few control parameters, the large values of the scattering lengths and the triton binding energy. Using a potential model with variable strength set to give values to the control parameters, we study the spectrum of nuclei in the region between the unitary limit and their physical values. In particular, we analyze how the binding energies emerge from the unitary limit forming the observed levels.

    Subjects:
    Nuclear Theory (nucl-th); physics.atm-clus (physics.atm-clus)
    arXiv:
    1903.08900 [pdf]
    PRC(2019)·38 citations
  2. 02

    [Submitted on 21 Mar 2019]

    Time reversal invariance violation in neutron-nucleus scattering

    Pavel Fadeev🇩🇪 · Victor V. Flambaum🇩🇪

    Planning and interpretation of the experiments searching for the time reversal (T) and parity (P) violation in neutron reactions require values of the matrix elements of the T,P-violating nuclear forces between nuclear compound states. We calculate the root mean square values and the ratio of the matrix elements of the T,P-violating and P-violating interactions using statistical theory based on the properties of chaotic compound states and present the results in terms of the fundamental parameters in four different forms: in terms of the constants of the contact nuclear interaction, meson exchange constants, QCD theta-term and quark chromo-EDMs. Using current limits on these parameters, we obtain the upper bounds on the ratio of the matrix elements.

    Comments:
    8 pages. Updated after publication
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Atomic Physics (physics.atom-ph)
    arXiv:
    1903.08937 [pdf]
    PRC(2019)·24 citations
  3. 03

    [Submitted on 20 Mar 2019] (cross-list from hep-lat)

    General Methods for Digital Quantum Simulation of Gauge Theories

    Henry Lamm🇺🇸 · Scott Lawrence🇺🇸 · Yukari Yamauchi (for the NuQS Collaboration)🇺🇸

    A general scheme is presented for simulating gauge theories, with matter fields, on a digital quantum computer. A Trotterized time-evolution operator that respects gauge symmetry is constructed, and a procedure for obtaining time-separated, gauge-invariant operators is detailed. We demonstrate the procedure on small lattices, including the simulation of a 2+1D non-Abelian gauge theory.

    Comments:
    13 pages, 7 figures, v3 includes clarifying comments, additional data and additional references. Matched published version
    Subjects:
    High Energy Physics — Lattice (hep-lat); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    1903.08807 [pdf]
    PRD(2019)·195 citations
  4. 04

    [Submitted on 21 Mar 2019] (cross-list from astro-ph.HE)

    New Neutron Star Equation of State with Quark-Hadron Crossover

    Gordon Baym🇺🇸 · Shun Furusawa🇯🇵 · Tetsuo Hatsuda🇯🇵 · Toru Kojo🇨🇳 · Hajime Togashi🇯🇵

    We present a much improved equation of state for neutron star matter, QHC19, with a smooth crossover from the hadronic regime at lower densities to the quark regime at higher densities. We now use the Togashi et al.~equation of state (Togashi:2017), a generalization of the Akmal-Pandharipande-Ravenhall equation of state of uniform nuclear matter, in the entire hadronic regime; the Togashi equation of state consistently describes non-uniform as well as uniform matter, and matter at beta equilibrium without the need for an interpolation between pure neutron and symmetric nuclear matter. We describe the quark matter regime at higher densities with the Nambu--Jona--Lasinio model, now identifying tight constraints on the phenomenological universal vector repulsion between quarks and the pairing interaction between quarks arising from the requirements of thermodynamic stability and causal propagation of sound. The resultant neutron star properties agree very well with the inferences of the LIGO/Virgo collaboration, from GW170817, of the pressure vs. baryon density, neutron star radii, and tidal deformabilities. The maximum neutron star mass allowed by QHC19 is 2.35 , consistent with all neutron star mass determinations.

    Comments:
    8 pages, 11 figures; v3) published version, appendix was added
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1903.08963 [pdf]
    ApJ(2019)·220 citations
  5. 05

    [Submitted on 21 Mar 2019] (cross-list from astro-ph.HE)

    Evidence for quark-matter cores in massive neutron stars

    Eemeli Annala🇫🇮 · Tyler Gorda🇺🇸 · Aleksi Kurkela🇨🇭 · Joonas Nättilä🇸🇪 · Aleksi Vuorinen🇫🇮

    The theory governing the strong nuclear force, Quantum Chromodynamics, predicts that at sufficiently high energy densities hadronic nuclear matter undergoes a deconfinement transition to a new phase of quarks and gluons. Although this has been observed in ultrarelativistic heavy-ion collisions, it is currently an open question whether quark matter exists inside neutron stars. By combining astrophysical observations and theoretical ab-initio calculations in a model-independent way, we find that the inferred properties of matter in the cores of neutron stars with mass corresponding to 1.4 solar masses are compatible with nuclear model calculations. However, the matter in the interior of maximally massive, stable neutron stars exhibits characteristics of the deconfined phase, which we interpret as evidence for the presence of quark-matter cores. For the heaviest reliably observed neutron stars with masses of about two solar masses, the presence of quark matter is found to be linked to the behaviour of the speed of sound c_s in strongly interacting matter. If the conformal bound (c_s)^2 < 1/3 is not strongly violated, massive neutron stars are predicted to have sizable quark-matter cores. This finding has important implications for the phenomenology of neutron stars, and affects the dynamics of neutron star mergers with at least one sufficiently massive participant.

    Comments:
    34 pages, including 8 pages main text + 10 pages methods; 8 figures. 3 EoS tables included as ancillary files. v2: Substantial changes from v1. Text shortened, with major changes to analysis and structure. Analysis and conclusions made more precise; title changed. Version accepted for publication in Nature Physics
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1903.09121 [pdf]
    Nat.Phys.(2020)·814 citations

Affiliations

first authorsco-authorsvia INSPIRE