Nuclear Theory·nucl-th

Tuesday·August 11, 2015

13 papers—6 primary·7 cross-listed

07
New Photodisintegration Model of GEANT4 for the $d γ \to n p$ Reaction with a Dibaryon Effective Field Theory
Jae Won Shin🇰🇷 · Chang Ho Hyun🇰🇷
We develop a new hadronic model for GEANT4 that is specialized for the disintegration of the deuteron by photons, $d γ \to n p$ . For the description of two-nucleon interactions, we employ a pionless effective field theory with dibaryon fields (dEFT). We apply the new model of GEANT4 (G4dEFT) to the calculations of the total and the differential cross sections in $d γ \to n p$ and compare the results with empirical data. As an application of the new model, we calculate the neutron yield from the $γ + CD_{2}$ process. G4dEFT predicts peaks for the neutron yield, but the existing model of GEANT4 does not show such behavior.
↳ nucl-exnucl-thJ.Korean Phys.Soc.(2016)·1 citation
08
Possible identifications of newly observed magnetar quasi-periodic oscillations as crustal shear modes
Hajime Sotani🇯🇵 · Kei Iida🇯🇵 · Kazuhiro Oyamatsu🇯🇵
Quasi-periodic oscillations (QPOs) discovered in soft-gamma repeaters (SGRs) are expected to help us to study the properties of matter in neutron stars. In earlier investigations, we identified the QPOs of frequencies below $\sim 100$ Hz observed in giant flares of SGR 1806 $-$ 20 and SGR 1900+14 as the crustal torsional oscillations. For this purpose, we calculated the frequencies of the fundamental torsional oscillations with various angular indices $ℓ$ , by changing the stellar mass and radius. In this work, we try to explain the additional QPO frequencies recently reported by Huppenkothen et al. (2014a,b) within the same framework as before except that we newly take into account the effect of electron screening, which acts to decrease the frequencies by a small amount. Those QPOs were discovered in two different SGRs, i.e., SGR 1806 $-$ 20 and SGR J1550 $-$ 5418. Then, we find that the newly observed QPO frequency in SGR 1806 $-$ 20 can be still identified as one of the frequencies of the fundamental torsional oscillations, while those in SGR J1550 $-$ 5418 can also be explained in terms of the torsional oscillations although the relevant angular indices are difficult to identify.
↳ astro-ph.HEnucl-thNew Astron.(2016)·50 citations
09
On $m_{T}$ dependence of femtoscopy scales for meson and baryon pairs
Yu. M. Sinyukov🇺🇦 · V. M. Shapoval🇺🇦 · V. Yu. Naboka🇺🇦
The $m_{T}$ -dependencies of the femto-scales, the so-called interferometry and source radii, are investigated within the hydrokinetic model for different types of particle pairs - pion-pion, kaon-kaon, proton-proton and proton-lambda, - produced in Pb+Pb and $p + p$ collisions at the LHC. In particular, such property of the femto-scales momentum behavior as $m_{T}$ -scaling is studied for the systems with (w) and without (w/o) intensive transverse flow, and also w and w/o re-scattering at the final afterburner stage of the matter evolution. The detail spatiotemporal description obtained within hydrokinetic model is compared with the simple analytical results for the spectra and longitudinal interferometry radii depending on the effective temperature on the hypersurface of maximal emission, proper time of such emission, and intensity of transverse flow. The derivation of the corresponding analytical formulas and discussion about a possibility for their utilization by the experimentalists for the simple femtoscopy data analysis is the main aim of this theoretical investigation.
↳ hep-phhep-exnucl-exnucl-thNPA(2016)·34 citations
10
A Comparative study of hyperon equations of state in supernova simulations
Prasanta Char🇮🇳 · Sarmistha Banik🇮🇳 · Debades Bandyopadhyay🇮🇳
A comparative study of the $Λ$ hyperon equations of state of Banik, Hempel and Banyopadhyay (BHB) \citep{bhb} and \citet{shen11} (denoted as HShen $Λ$ ) for core collapse supernova (CCSN) simulations is carried out in this work. The dynamical evolution of a protoneutron star (PNS) into a black hole is investigated in core collapse supernova simulations in the general relativistic one dimensional code using the BHB $Λ ϕ$ and HShen $Λ$ equation of state (EoS) tables and different progenitor models from Woosley and Heger \citep{Woos}. Radial profiles of the mass fractions of baryons, the density as well as the temperature in the PNS at different moments in time, are compared for both EoS tables. The behaviour of the central density of the PNS with time is demonstrated for those two $Λ$ hyperon EoS tables and compared with their corresponding nuclear EoS tables. It is observed that the black hole formation time is higher in the BHB $Λ ϕ$ case than in the HShen $Λ$ EoS for the entire set of progenitor models adopted here, because the repulsive $Λ$ - $Λ$ interaction makes the BHB $Λ ϕ$ EoS stiffer. Neutrino emission with the $Λ$ hyperon EoS ceases earlier than that of its nuclear counterpart. The long duration evolution of the shock radius and gravitational mass of the PNS after a successful supernova explosion with enhanced neutrino heating are studied with the BHB $Λ ϕ$ EoS and $s$ 20WH07 progenitor model. The PNS is found to remain stable for 4 s and might evolve into a cold neutron star.
↳ astro-ph.HEnucl-thApJ(2015)·27 citations
11
The Lamb shift in muonic hydrogen and the proton radius from effective field theories
Clara Peset🇪🇸 · Antonio Pineda🇪🇸
We comprehensively analyse the theoretical prediction for the Lamb shift in muonic hydrogen, and the associated determination of the proton radius. We use effective field theories. This allows us to relate the proton radius with well-defined objects in quantum field theory, eliminating unnecessary model dependence. The use of effective field theories also helps us to organize the computation so that we can clearly state the parametric accuracy of the result. In this paper we review all (and check several of) the contributions to the energy shift of order $α^{5}$ , as well as those that scale like $α^{6} \times$ logarithms in the context of non-relativistic effective field theories of QED.
↳ hep-phnucl-thphysics.atom-phEPJA(2015)·34 citations
12
Semi-relativistic wave-phase approximation for two-body spinless bound states in 1+1 dimensions
K.-E. Thylwe · S. Belov
An approximate quantum-mechanical two-body equation for spinless particles incorporating relativistic kinematics is derived. The derivation is based on the relativistic energy-momentum relation $m c^{2} + ϵ = m^{2} c^{4} + p^{2} c^{2} + V$ for each single particle, where $m c^{2}$ is the particle rest mass energy, $p$ its linear momentum, $ϵ$ its dynamical energy, and $V$ being the time-like vector interaction potential. The resulting two-body equation assumes rapid wave oscillations in a single, slowly varying potential well. A Bohr-Sommerfeld-type quantization condition is obtained. The approximation is compared to exact results for the harmonic potential.
↳ quant-phmath-phmath.MPnucl-th0 citations
13
Simple way to the high-temperature expansion of relativistic Fermi-Dirac integrals
A.S. Khvorostukhin🇷🇺
The pressure of an ideal relativistic Fermi gas is computed as an infinite series for high temperatures at nonzero chemical potentials. The expansion of the particle number density, scalar density, and entropy density as first derivatives of the pressure is also found.
↳ math-phhep-phhep-thmath.MP+1PRD(2015)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE

New Photodisintegration Model of GEANT4 for the dγ→np Reaction with a Dibaryon Effective Field Theory

Possible identifications of newly observed magnetar quasi-periodic oscillations as crustal shear modes

On mT​ dependence of femtoscopy scales for meson and baryon pairs

A Comparative study of hyperon equations of state in supernova simulations

The Lamb shift in muonic hydrogen and the proton radius from effective field theories

Semi-relativistic wave-phase approximation for two-body spinless bound states in 1+1 dimensions

Simple way to the high-temperature expansion of relativistic Fermi-Dirac integrals

Affiliations

New Photodisintegration Model of GEANT4 for the $d γ \to n p$ Reaction with a Dibaryon Effective Field Theory

On $m_{T}$ dependence of femtoscopy scales for meson and baryon pairs