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Nuclear Theory·nucl-th

Wednesday·June 6, 2018

12 papers—8 primary·4 cross-listed

All12Primary8Cross-lists4
  1. 09

    Glitch Behavior of Pulsars and Contribution from Neutron Star Crust

    Avishek Basu · Prasanta Char · Rana Nandi · Bhal Chandra Joshi · Debades Bandyopadhyay

    Pulsars are highly magnetized rotating neutron stars with a very stable rotation speed. Irrespective of their stable rotation rate, many pulsars have been observed with the sudden jump in the rotation rate, which is known as pulsar glitch. The glitch phenomena are considered to be an exhibit of superfluidity of neutron matter inside the neutron star's crustal region. The magnitude of such rapid change in rotation rate relative to their stable rotation frequency can quantify the moment of inertia of the crustal region to the total moment of inertia of the star called as the fractional moment of inertia (FMI). In this paper, we have calculated FMI for different masses of the star using six different representative unified equations of state (EoS) constructed under Relativistic Mean Field (RMF) framework. We have performed an event-wise comparison of FMI obtained from data with that of theoretically calculated values with and without considering the entrainment effect. It is found that larger glitches can't be explained by crustal FMI alone, even without the entrainment.

    ↳ astro-ph.HEgr-qcnucl-thApJ(2018)·27 citations
  2. 10

    Two-photon exchange correction in elastic lepton-proton scattering

    Oleksandr Tomalak🇩🇪

    We present the dispersion relation approach based on unitarity and analyticity to evaluate the two-photon exchange contribution to elastic electron-proton scattering. The leading elastic and first inelastic intermediate state contributions are accounted for in the region of small momentum transfer based on the available data input. The novel methods of analytical continuation allow us to exploit the MAMI form factor data and the MAID parameterization for the pion electroproduction amplitudes as input in the calculation. The results are compared to the recent CLAS, VEPP-3 and OLYMPUS data as well as to the full two-photon exchange correction in the near-forward approximation, which is based on the Christy and Bosted unpolarized structure functions fit. Additionally, predictions are given for a forthcoming muon-proton scattering experiment.

    ↳ hep-phnucl-exnucl-thFew Body Syst.(2018)·15 citations
  3. 11

    Cosmological Constant Effects on the Properties of Mass Twin Compact Stars

    Noshad Khosravi Largani🇮🇷 · David E. Alvarez-Castillo🇷🇺

    We present a systematic investigation of the cosmological constant effects in compact stars interiors in the framework of Einstein's gravity. Consideration of a cosmological constant in compact stars is motivated by the mechanism of acceleration of the observable universe, where is usually related to the dark energy. In particular, we consider compact star mass twins, hybrid neutron stars that populate both the second and third branch of the mass-radius diagram. For those models, the need of consideration of excluded volume effects in the equation of state, resulting from the finite size volume of nucleons, leads to a stiffening of matter causing compact stars to acquire higher mass and radius values. We demonstrate that certain values of the cosmological constant can also modify the compact star properties but in an opposite way. In addition, we find that the inclusion of can have a similar effect to the existence of pasta phases at the hadron-quark interface.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thEPJ Web Conf.(2019)·6 citations
  4. 12

    Phase Unwrapping and One-Dimensional Sign Problems

    William Detmold🇺🇸 · Gurtej Kanwar🇺🇸 · Michael L. Wagman🇺🇸

    Sign problems in path integrals arise when different field configurations contribute with different signs or phases. Phase unwrapping describes a family of signal processing techniques in which phase differences between elements of a time series are integrated to construct non-compact unwrapped phase differences. By combining phase unwrapping with a cumulant expansion, path integrals with sign problems arising from phase fluctuations can be systematically approximated as linear combinations of path integrals without sign problems. This work explores phase unwrapping in zero-plus-one-dimensional complex scalar field theory. Results with improved signal-to-noise ratios for the spectrum of scalar field theory can be obtained from unwrapped phases, but the size of cumulant expansion truncation errors is found to be undesirably sensitive to the parameters of the phase unwrapping algorithm employed. It is argued that this numerical sensitivity arises from discretization artifacts that become large when phases fluctuate close to singularities of a complex logarithm in the definition of the unwrapped phase.

    ↳ hep-latcond-mat.stat-mechhep-thnucl-th+1PRD(2018)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE