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Nuclear Theory·nucl-th

Friday·September 1, 2017

4 papers—3 primary·1 cross-listed

All4Primary3Cross-lists1
  1. 01

    [Submitted on 31 Aug 2017]

    Temperature effects on nuclear pseudospin symmetry in the Dirac-Hartree-Bogoliubov formalism

    R. Lisboa🇧🇷 · P. Alberto🇵🇹 · B. V. Carlson🇧🇷 · M. Malheiro🇧🇷

    We present finite temperature Dirac-Hartree-Bogoliubov (FTDHB) calculations for the tin isotope chain to study the dependence of pseudospin on the nuclear temperature. In the FTDHB calculation, the density dependence of the self-consistent relativistic mean fields, the pairing, and the vapor phase that takes into account the unbound nucleon states are considered self-consistently. The mean field potentials obtained in the FTDHB calculations are fit by Woods-Saxon (WS) potentials to examine how the WS parameters are related to the energy splitting of the pseudospin pairs as the temperature increases. We find that the nuclear potential surface diffuseness is the main driver for the pseudospin splittings and that it increases as the temperature grows. We conclude that pseudospin symmetry is better realized when the nuclear temperature increases. The results confirm the findings of previous works using RMF theory at , namely that the correlation between the pseudospin splitting and the parameters of the Woods-Saxon potentials implies that pseudospin symmetry is a dynamical symmetry in nuclei. We show that the dynamical nature of the pseudospin symmetry remains when the temperature is considered in a realistic calculation of the tin isotopes, such as that of the Dirac-Hartree-Bogoliubov formalism.

    Comments:
    21 pages, 17 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1708.09511 [pdf]
    PRC(2017)·5 citations
  2. 02

    [Submitted on 31 Aug 2017]

    Isovector properties of quark matter and quark stars in an isospin-dependent confining model

    Peng-Cheng Chu🇨🇳 · Lie-Wen Chen🇨🇳

    The confining quark matter (CQM) model, in which the confinement and asymptotic freedom are modeled via the Richardson potential for quark-quark vector interaction and the chiral symmetry restoration at high density is described by the density dependent quark mass, is extended to include isospin dependence of the quark mass. Within this extended isospin-dependent confining quark matter (ICQM) model, we study the properties of strange quark matter and quark stars. We find that including isospin dependence of the quark mass can significantly influence the quark matter symmetry energy, the stability of strange quark matter and the mass-radius relation of quark stars. In particular, we demonstrate although the recently discovered large mass pulsars PSR J1614.2230 and PSR J0348+0432 with masses around two times solar mass () cannot be quark stars within the original CQM model, they can be well described by quark stars in the ICQM model if the isospin dependence of quark mass is strong enough so that the quark matter symmetry energy is about four times that of a free quark gas. We also discuss the effects of the density dependence of quark mass on the properties of quark stars. Our results indicate that the heavy quark stars with mass around (if exist) can put strong constraints on isospin and density dependence of the quark mass as well as the quark matter symmetry energy.

    Comments:
    10 pages, 6 figures, 2 tables. Presentation improved, 2 tables and discussions added. Accepted version to appear in PRD
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    1708.09599 [pdf]
    PRD(2017)·33 citations
  3. 03

    [Submitted on 31 Aug 2017]

    Impact of the quenching of on the sensitivity of experiments

    Jouni Suhonen🇫🇮

    Detection of the neutrinoless () decay is of high priority in the particle- and neutrino-physics communities. The detectability of this decay mode is strongly influenced by the value of the weak axial-vector coupling constant . The recent nuclear-model analyses of and decays suggest that the value of could be dramatically quenched, reaching ratios of , where is the free, neutron-decay, value of . The effects of this quenching appear devastating for the sensitivity of the present and future experiments since the 4 power of this ratio scales the half-lives. This, in turn, could lead to some two orders of magnitude less sensitivity for the experiments. In the present Letter it is shown that by using a consistent approach to both the two-neutrino and decays by the proton-neutron quasiparticle random-phase approximation (pnQRPA), the feared two-orders-of-magnitude reduction in the sensitivity of the experiments actually shrinks to a reduction by factors in the range . This certainly has dramatic consequences for the potential to detect the decay.

    Comments:
    5 pages, 3 figures, published in PRC
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1708.09604 [pdf]
    PRC(2017)·76 citations
  4. 04

    [Submitted on 30 Aug 2017] (cross-list from hep-ph)

    Neutrinoless double beta decay in chiral effective field theory: lepton number violation at dimension seven

    V. Cirigliano🇺🇸 · W. Dekens🇺🇸 · J. de Vries🇳🇱 · M. L. Graesser🇺🇸 · E. Mereghetti🇺🇸

    We analyze neutrinoless double beta decay () within the framework of the Standard Model Effective Field Theory. Apart from the dimension-five Weinberg operator, the first contributions appear at dimension seven. We classify the operators and evolve them to the electroweak scale, where we match them to effective dimension-six, -seven, and -nine operators. In the next step, after renormalization group evolution to the QCD scale, we construct the chiral Lagrangian arising from these operators. We develop a power-counting scheme and derive the two-nucleon currents up to leading order in the power counting for each lepton-number-violating operator. We argue that the leading-order contribution to the decay rate depends on a relatively small number of nuclear matrix elements. We test our power counting by comparing nuclear matrix elements obtained by various methods and by different groups. We find that the power counting works well for nuclear matrix elements calculated from a specific method, while, as in the case of light Majorana neutrino exchange, the overall magnitude of the matrix elements can differ by factors of two to three between methods. We calculate the constraints that can be set on dimension-seven lepton-number-violating operators from experiments and study the interplay between dimension-five and -seven operators, discussing how dimension-seven contributions affect the interpretation of in terms of the effective Majorana mass .

    Comments:
    Matches version published in JHEP
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1708.09390 [pdf]
    JHEP(2017)·145 citations

Affiliations

first authorsco-authorsvia INSPIRE