Nuclear Theory·nucl-th

Wednesday·November 25, 2020

9 papers—5 primary·4 cross-listed

06
[Submitted on 24 Nov 2020] (cross-list from astro-ph.HE)
Astromers in the radioactive decay of r-process nuclei
G. Wendell Misch · T. M. Sprouse · M. R. Mumpower
We study the impact of astrophysically relevant nuclear isomers (astromers) in the context of the rapid neutron capture process (r-process) nucleosynthesis. We compute thermally mediated transition rates between long-lived isomers and the corresponding ground states in neutron-rich nuclei. We calculate the temperature-dependent beta-decay feeding factors which represent the fraction of material going to each of the isomer and ground state daughter species from the beta-decay parent species. We simulate nucleosynthesis by including as separate species nuclear excited states with measured terrestrial half-lives greater than 100 microseconds. We find a variety of isomers throughout the chart of nuclides are populated, and we identify those most likely to be influential. We comment on the capacity of isomer production to alter radioactive heating in an r-process environment.
Comments:
8 pages, 3 figures, 1 table
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2011.11889 [pdf]
ApJL(2021)·38 citations
07
[Submitted on 24 Nov 2020] (cross-list from astro-ph.HE)
$R$ -mode Stability of GW190814's Secondary Component as a Supermassive and Superfast Pulsar
Xia Zhou · Ang Li · Bao-An Li
The nature of GW190814's secondary component $m_{2}$ of mass $(2.50 - 2.67) M_{⊙}$ in the mass gap between the currently known maximum mass of neutron stars and the minimum mass of black holes is currently under hot debate. Among the many possibilities proposed in the literature, the $m_{2}$ was suggested as a superfast pulsar while its r-mode stability against the run-away gravitational radiation through the Chandrasekhar-Friedman-Schutz mechanism is still unknown. Using those fulfilling all currently known astrophysical and nuclear physics constraints among a sample of 33 unified equation of states (EOSs) constructed previously by Fortin {\it et al.} (2016) using the same nuclear interactions from the crust to the core consistently, we compare the minimum frequency required for the $m_{2}$ to rotationally sustain a mass higher than $2.50 M_{⊙}$ with the critical frequency above which the r-mode instability occurs. We use two extreme damping models assuming the crust is either perfectly rigid or elastic. Using the stability of 19 observed low-mass x-ray binaries as an indication that the rigid crust damping of the r-mode dominates within the models studied, we find that the $m_{2}$ is r-mode stable while rotating with a frequency higher than 870.2 Hz (0.744 times its Kepler frequency of 1169.6 Hz) as long as its temperate is lower than about $3.9 \times 1 0^{7} K$ , further supporting the proposal that GW190814's secondary component is a supermassive and superfast pulsar.
Comments:
9 pages, 5 figures, 1 table, version accepted for publication in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2011.11934 [pdf]
ApJ(2021)·34 citations
08
[Submitted on 24 Nov 2020] (cross-list from hep-lat)
Conundrums at Finite Density
Rajiv V. Gavai🇩🇪
Extending the successes of lattice quantum chromodynamics(QCD) at zero as well as nonzero temperatures to nonzero density is extremely desirable in view of the quest for the QCD phase diagram both theoretically and experimentally. It turns out though to give rise to some conundrums whose resolution may assist progress in this exciting but difficult area, and should therefore be sought actively.
Comments:
11 pages, 6 figures, To appear in the proceeding of the international conference on "Criticality in QCD and the Hadron Resonance Gas", 29-31 July 2020, Wroclaw, Poland
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.11999 [pdf]
Acta Phys.Polon.Supp.(2021)·0 citations
09
[Submitted on 24 Nov 2020] (cross-list from hep-lat)
Scale setting the Möbius Domain Wall Fermion on gradient-flowed HISQ action using the omega baryon mass and the gradient-flow scales $t_{0}$ and $w_{0}$
Nolan Miller🇺🇸 · Logan C Carpenter🇺🇸 · Evan Berkowitz🇺🇸 · Chia Cheng Chang🇯🇵 · Ben Hörz🇺🇸 · Dean Howarth🇺🇸 · Henry Monge-Camacho🇨🇷 · Enrico Rinaldi🇯🇵 · David A. Brantley🇺🇸 · Christopher Körber🇺🇸 · Chris Bouchard🇬🇧 · M.A. Clark🇺🇸 and 5 other authors
We report on a sub-percent scale determination using the omega baryon mass and gradient-flow methods. The calculations are performed on 22 ensembles of $N_{f} = 2 + 1 + 1$ highly improved, rooted staggered sea-quark configurations generated by the MILC and CalLat Collaborations. The valence quark action used is Möbius Domain-Wall fermions solved on these configurations after a gradient-flow smearing is applied with a flowtime of $t_{gf} = 1$ in lattice units. The ensembles span four lattice spacings in the range $0.06 ≲ a ≲ 0.15$ fm, six pion masses in the range $130 ≲ m_{π} ≲ 400$ MeV and multiple lattice volumes. On each ensemble, the gradient-flow scales $t_{0} / a^{2}$ and $w_{0} / a$ and the omega baryon mass $a m_{Ω}$ are computed. The dimensionless product of these quantities is then extrapolated to the continuum and infinite volume limits and interpolated to the physical light, strange and charm quark mass point in the isospin limit, resulting in the determination of $t_{0} = 0.1422 (14)$ fm and $w_{0} = 0.1709 (11)$ fm with all sources of statistical and systematic uncertainty accounted for. The dominant uncertainty in this result is the stochastic uncertainty, providing a clear path for a few-per-mille uncertainty, as recently obtained by the Budapest-Marseille-Wuppertal Collaboration.
Comments:
v3: Published version; v2: Added determination of t_0 as well as w_0; v1: 13 pages plus appendices. The correlation function data, mass results and analysis code accompanying this publication can be found at this github repository: https://github.com/callat-qcd/project_scale_setting_mdwf_hisq
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2011.12166 [pdf]
PRD(2021)·40 citations

Affiliations

first authorsco-authorsvia INSPIRE

Astromers in the radioactive decay of r-process nuclei

R-mode Stability of GW190814's Secondary Component as a Supermassive and Superfast Pulsar

Conundrums at Finite Density

Scale setting the Möbius Domain Wall Fermion on gradient-flowed HISQ action using the omega baryon mass and the gradient-flow scales t0​ and w0​

Affiliations

$R$ -mode Stability of GW190814's Secondary Component as a Supermassive and Superfast Pulsar

Scale setting the Möbius Domain Wall Fermion on gradient-flowed HISQ action using the omega baryon mass and the gradient-flow scales $t_{0}$ and $w_{0}$