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Nuclear Theory·nucl-th

Friday·September 29, 2017

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    Current matrix element in HAL QCD's wave function equivalent potential method

    Kai Watanabe🇯🇵 · Noriyoshi Ishii🇯🇵

    We give a formula to calculate a matrix element of a conserved current in the effective quantum mechanics defined by the wave function equivalent potentials proposed by HAL QCD collaboration. As a first step, a non-relativistic field theory with two channel coupling is considered as the original theory, with which a wave function equivalent HAL QCD potential is obtained in a closed analytic form. The external field method is used to derive the formula by demanding that the result should agree with the original theory. With this formula, the matrix element is obtained by sandwiching the effective current operator between the left and the right eigen functions of the effective Hamiltonian associated with the HAL QCD potential. In addition to the naive one-body current, the effective current operator contains an additional two-body term emerging from the degrees of freedom which has been integrated out.

    ↳ hep-lathep-phnucl-thPTEP(2018)·1 citation
  2. 05

    Transport properties of nuclear pasta phase with quantum molecular dynamics

    Rana Nandi · Stefan Schramm

    We study the transport properties of nuclear pasta for a wide range of density, temperature and proton fractions, relevant for different astrophysical scenarios adopting a quantum molecular dynamics model. In particular, we estimate the values of shear viscosity as well as electrical and thermal conductivities by calculating the static structure factor using simulation data. In the density and temperature range where the pasta phase appears, the static structure factor shows irregular behavior. The presence of a slab phase greatly enhances the peak in . However, the effect of irregularities in on the transport coefficients is not very dramatic. The values of all three transport coefficients are found to have the same orders of magnitude as found in theoretical calculations for the inner crust matter of neutron stars without the pasta phase and therefore, is in contrast to earlier speculations that a pasta layer might be highly resistive, both thermally and electrically.

    ↳ astro-ph.HEnucl-thApJ(2018)·41 citations
  3. 06

    Resolving the SELEX--LHCb Double-Charm Baryon Conflict: The Impact of Intrinsic Heavy-Quark Hadroproduction and Supersymmetric Light-Front Holographic QCD

    S.J. Brodsky🇺🇸 · S. Groote🇪🇪 · S. Koshkarev🇪🇪

    In this paper we show that the intrinsic heavy-quark QCD mechanism for the hadroproduction of heavy hadrons at large can resolve the apparent conflict between measurements of double-charm baryons by the SELEX fixed-target experiment and the LHCb experiment at the LHC collider. We show that both experiments are compatible, and that both results can be correct. The observed spectroscopy of double-charm hadrons is in agreement with the predictions of supersymmetric light front holographic QCD.

    ↳ hep-phnucl-thEPJC(2018)·39 citations
  4. 07

    Probing low-mass vector bosons with parity nonconservation and nuclear anapole moment measurements in atoms and molecules

    V. A. Dzuba🇦🇺 · V. V. Flambaum🇩🇪 · Y. V. Stadnik🇦🇺

    In the presence of P-violating interactions, the exchange of vector bosons between electrons and nucleons induces parity-nonconserving (PNC) effects in atoms and molecules, while the exchange of vector bosons between nucleons induces anapole moments of nuclei. We perform calculations of such vector-mediated PNC effects in Cs, Ba, Yb, Tl, Fr and Ra using the same relativistic many-body approaches as in earlier calculations of standard-model PNC effects, but with the long-range operator of the weak interaction. We calculate nuclear anapole moments due to vector boson exchange using a simple nuclear model. From measured and predicted (within the standard model) values for the PNC amplitudes in Cs, Yb and Tl, as well as the nuclear anapole moment of Cs, we constrain the P-violating vector-pseudovector nucleon-electron and nucleon-proton interactions mediated by a generic vector boson of arbitrary mass. Our limits improve on existing bounds from other experiments by many orders of magnitude over a very large range of vector-boson masses.

    ↳ physics.atom-phhep-phnucl-thPRL(2017)·59 citations
  5. 08

    Prospects for Improved Understanding of Isotopic Reactor Antineutrino Fluxes

    Y. Gebre🇺🇸 · B. R. Littlejohn🇺🇸 · P. T. Surukuchi🇺🇸

    Predictions of antineutrino fluxes produced by fission isotopes in a nuclear reactor have recently received increased scrutiny due to observed differences in predicted and measured inverse beta decay (IBD) yields, referred to as the 'reactor antineutrino flux anomaly.' In this paper, global fits are applied to existing IBD yield measurements to produce constraints on antineutrino production by individual plutonium and uranium fission isotopes. We find that fits including measurements from highly 235U-enriched cores and fits including Daya Bay's new fuel evolution result produce discrepant best-fit IBD yields for 235U and 239Pu. This discrepancy can be alleviated in a global analysis of all datasets through simultaneous fitting of 239Pu, 235U, and 238U yields. The measured IBD yield of U238 in this analysis is (7.02 +/- 1.65) x 10^-43 cm2/fission, nearly two standard deviations below existing predictions. Future hypothetical IBD yield measurements by short-baseline reactor experiments are examined to determine their possible impact on global understanding of isotopic IBD yields. It is found that future improved short-baseline IBD yield measurements at both high-enriched and low-enriched cores can significantly improve constraints for 235U, 238U, and 239Pu, providing comparable or superior precision to existing conversion- and summation-based antineutrino flux predictions. Systematic and experimental requirements for these future measurements are also investigated.

    ↳ hep-phnucl-exnucl-thPRD(2018)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE