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Nuclear Theory·nucl-th

Monday·August 17, 2020

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 01

    [Submitted on 13 Aug 2020]

    Following nuclei through nucleosynthesis: a novel tracing technique

    T. M. Sprouse · M. R. Mumpower · R. Surman

    Astrophysical nucleosynthesis is a family of diverse processes by which atomic nuclei undergo nuclear reactions and decays to form new nuclei. The complex nature of nucleosynthesis, which can involve as many as tens of thousands of interactions between thousands of nuclei, makes it difficult to study any one of these interactions in isolation using standard approaches. In this work, we present a new technique, nucleosynthesis tracing, that we use to quantify the specific role of individual nuclear reaction, decay, and fission processes in relationship to nucleosynthesis as a whole. We apply this technique to study fission and -decay as they occur in the rapid neutron capture () process of nucleosynthesis.

    Comments:
    18 pages, 10 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2008.06075 [pdf]
    PRC(2021)·38 citations
  2. 02

    [Submitted on 14 Aug 2020]

    Light element () production from spontaneous ternary fission of Cf

    G. Röpke · J. B. Natowitz · H. Pais

    The yields of light elements () obtained from spontaneous ternary fission of Cf are treated within a nonequilibrium approach, and the contribution of unstable nuclei and excited bound states is taken into account. These light cluster yields may be used to probe dense matter, and to infer in-medium corrections. Continuum correlations are calculated from scattering phase shifts using the Beth-Uhlenbeck formula, and the effect of medium modification is estimated. The relevant distribution is reconstructed from the measured yields of isotopes. This describes the state of the nucleon system at scission and cluster formation, using only three Lagrange parameters which are the nonequilibrium counterparts of the temperature and chemical potentials, as defined in thermodynamic equilibrium. We concluded that a simple nuclear statistical equilibrium model neglecting continuum correlations and medium effects is not able to describe the measured distribution of H and He isotopes. Moreover, the freeze-out concept may serve as an important ingredient to the nonequilibrium approach using the relevant statistical operator concept.

    Comments:
    13 pages, 1 figure
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    2008.06321 [pdf]
    EPJA(2020)·6 citations
  3. 03

    [Submitted on 13 Aug 2020] (cross-list from hep-ph)

    Statistical interpretation of sterile neutrino oscillation searches at reactors

    Pilar Coloma🇪🇸 · Patrick Huber🇺🇸 · Thomas Schwetz🇩🇪

    A considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks' theorem, whereby the assumption is made that the log-likelihood is -distributed. However, it is well known that the preconditions for the validity of Wilks' theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6\, level, compared to 3.2\, obtained under the assumption that Wilks' theorem applies.

    Comments:
    24 pages, 6 figures. v2: minor changes, references added, matches version accepted in EPJC
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2008.06083 [pdf]
    EPJC(2021)·38 citations
  4. 04

    [Submitted on 13 Aug 2020] (cross-list from astro-ph.HE)

    Total Energy in Supernova Neutrinos and the Tidal Deformability and Binding Energy of Neutron Stars

    Brendan Reed🇺🇸 · C. J. Horowitz🇺🇸

    The energy radiated in supernova neutrinos is a fundamental quantity that is closely related to the gravitational binding energy of a neutron star. Recently the tidal deformability of neutron stars was constrained by gravitational wave observations. By considering several equations of state, we find a strong correlation between the tidal deformability and neutron star binding energy. We use this correlation to sharpen predictions of the binding energy of neutron stars and the total neutrino energy in supernovae. We find a minimum binding energy for a neutron star formed in a supernova of ergs. Should the neutrino energy in a supernova be significantly below this value, it would strongly suggest new unobserved particles are carrying away some of the supernova energy. Alternatively, if the neutrino energy is observed above ergs, it would strongly imply the formation of a (perhaps surprisingly) massive neutron star.

    Comments:
    8 pages, 6 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2008.06108 [pdf]
    PRD(2020)·13 citations
  5. 05

    [Submitted on 14 Aug 2020] (cross-list from hep-ph)

    Nonperturbative quark-antiquark interactions in mesonic form factors

    Edward Shuryak🇺🇸 · Ismail Zahed🇺🇸

    The existing theory of hard exclusive QCD processes is based on two assumptions: (i) into a times light front distribution amplitudes (DA's); (ii) use of perturbative gluon exchanges within the hard block. However, unlike DIS and jet physics, the characteristic momentum transfer involved in the factorized block is not large enough for this theory to be phenomenologically successful. In this work, we revisit the latter assumption (ii), by explicitly calculating the contributions to the hard block, and show that they contribute substantially to the vector, scalar and gravitational form factors of the pseudoscalar, scalar and vector mesons, over a wide range of momentum transfer.

    Comments:
    82 pages, 17 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2008.06169 [pdf]
    PRD(2021)·27 citations
  6. 06

    [Submitted on 13 Aug 2020] (cross-list from astro-ph.HE)

    Vortex lattice in rotating neutron spin-triplet superfluid

    Lev B. Leinson

    In the Ginzburg-Landau limit, a possible texture without singular cores in a rotating neutron spin-triplet superfluid is studied. It is constructed the lattice of non-singular vortices with a vorticity diffusely distributed over the entire unit cell. The upper limit of the free energy associated with this structure is estimated, and the result shows that non-singular vortices are more preferable in the core of rotating neutron stars than ordinary linear singular vortices. The order parameter of the studied neutron system belongs to the unitary class. This implies that the superfluid under consideration does not have spin polarization and the core-less P vortices do not have magnetization, which makes electron scattering by vortices ineffective. For the same reason, pinning with flux tubes is also suppressed. This can affect the hydrodynamics of superfluid neutron stars.

    Comments:
    7 pages, 5 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2008.06328 [pdf]
    MNRAS(2020)·12 citations
  7. 07

    [Submitted on 14 Aug 2020] (cross-list from astro-ph.HE)

    Delta baryons and diquark formation in the cores of neutron stars

    German Malfatti🇦🇷 · Milva G. Orsaria🇦🇷 · Ignacio F. Ranea-Sandoval🇦🇷 · Gustavo A. Contrera🇦🇷 · Fridolin Weber🇺🇸

    We investigate the hadron-quark phase transition in cold neutron stars in light of (i) the observed limits on the maximum-mass of heavy pulsars, (ii) constraints on the tidal properties inferred from the gravitational waves emitted in binary neutron-star mergers, and (iii) mass and radius constraints derived from the observation of hot spots on neutron star observed with NICER. Special attention is directed to the possible presence of baryons in neutron star matter. Our results indicate that this particle could make up a large fraction of the baryons in neutron stars and thus have a significant effect on the properties of such objects, particularly on their radii. This is partially caused by the low density appearance of s for a wide range of theoretically defensible sets of meson-hyperon, SU(3) ESC08 model, and meson- coupling constants. The transition of hadronic matter to quark matter, treated in the 2SC+s condensation phase, is found to occur only in neutron stars very close to the mass peak. Nevertheless, quark matter may still constitute an appreciable fraction of the stars' total matter if the phase transition is treated as Maxwell-like (sharp), in which case the neutron stars located beyond the gravitational mass peak would remain stable against gravitational collapse. In this case, the instability against gravitational collapse is shifted to a new (terminal) mass different from the maximum-mass of the stellar sequence, giving rise to stable compact objects with the same gravitational masses as those of the neutron stars on the traditional branch, but whose radii are smaller by up to 1 km. All models for the equation of state of our study fall comfortably within the bound established very recently by Annala {\it et al.} (Nature Physics, 2020)

    Comments:
    18 Pages, 13 Figures, Accepted for publication in Physical Review D, in production
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2008.06459 [pdf]
    PRD(2020)·68 citations

Affiliations

first authorsco-authorsvia INSPIRE