Nuclear Theory·nucl-th

Monday·September 14, 2020

8 papers—6 primary·2 cross-listed

01
[Submitted on 10 Sept 2020]
Formalism of hydrodynamics with spin degrees of freedom
Rajeev Singh🇵🇱
In this article we review the perfect-fluid hydrodynamics with spin framework proposed recently. This framework generalises the standard relativistic hydrodynamics framework to include spin degrees of freedom and provides a natural method to describe the spin polarization evolution of massive spin 1/2 particles. This formalism is based on the GLW (de Groot - van Leeuwen - van Weert) energy-momentum tensor and spin tensor. We show here using Bjorken model that how this spin hydrodynamics framework may be used for the determination of the observables which describes the particle polarization measured in the experiment.
Comments:
Presented at The Eighth Annual Conference on Large Hadron Collider Physics-LHCP2020, 25-30 May, 2020. 5 pages, 5 figures. Revised and accepted version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2009.05130 [pdf]
PoS(2021)·2 citations
02
[Submitted on 11 Sept 2020]
Strangeness-changing Rates and Hyperonic Bulk Viscosity in Neutron Star Mergers
Mark G. Alford🇺🇸 · Alexander Haber🇺🇸
In this paper we present a computation of the rates of strangeness-changing processes and the resultant bulk viscosity in matter at the densities and temperatures typical of neutron star mergers. To deal with the high temperature in this environment we go beyond the Fermi surface approximation in our rate calculations and numerically evaluate the full phase space integral. We include processes where quarks move between baryons via meson exchange: these have generally been omitted in previous analyses but provide the dominant contribution to the rates of strangeness-changing processes and the bulk viscosity. The calculation of these rates is an essential step towards any calculation of dissipation mechanisms in hyperonic matter in mergers. As one application, we calculate the dissipation times for density oscillations at the frequencies seen in merger simulations. We find that hyperon bulk viscosity for temperatures in the MeV regime can probably be neglected in this context, but becomes highly relevant for keV-range temperatures.
Comments:
17 pages, 11 figures v2: corrected computation of susceptibilities, resonant temperature for maximum bulk viscosity shifted to much lower temperatures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2009.05181 [pdf]
PRC(2021)·61 citations
03
[Submitted on 11 Sept 2020]
Impact of the neutron-star deformability on equation of state parameters
C.Y. Tsang · M.B. Tsang · Pawel Danielewicz · W.G. Lynch · F.J. Fattoyev
We use a Bayesian inference analysis to explore the sensitivity of Taylor expansion parameters of the nuclear equation of state (EOS) to the neutron star dimensionless tidal deformability ( $Λ$ ) on 1 to 2 solar masses neutron stars. A global power law dependence between tidal deformability and compactness parameter (M/R) is verified over this mass region. To avoid superfluous correlations between the expansion parameters, we use a correlation-free EOS model based on a recently published meta-modeling approach. We find that assumptions in the prior distribution strongly influence the constraints on $Λ$ . The $Λ$ constraints obtained from the neutron star merger event GW170817 prefer low values of $L_{sym}$ and $K_{sym}$ , for a canonical neutron star with 1.4 solar mass. For neutron star with mass $< 1.6$ solar mass, $L_{sym}$ and $K_{sym}$ are highly correlated with the tidal deformability. For more massive neutron stars, the tidal deformability is more strongly correlated with higher order Taylor expansion parameters.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.05239 [pdf]
PRC(2020)·44 citations
04
[Submitted on 11 Sept 2020]
Probing Lorentz violation in $2 ν β β$ using single electron spectra and angular correlations
O.V. Nitescu (1,2,3)🇷🇴 · S.A. Ghinescu (1,2,3)🇷🇴 · M. Mirea (1,2)🇷🇴 · S. Stoica (1,2)🇷🇴
We show that the current search for Lorentz invariance violation (LIV) in the summed energy spectra of electrons in $2 ν β β$ decay can be extended by investigating the single electron spectra and the angular correlation between the emitted electrons. We derive and calculate the LIV contributions to these spectra associated with the anisotropic part of the countershaded operator and controlled through the coefficient $a ˚_{of}^{(3)}$ and discuss possible signatures that may be probed in experiments. First, we show that some distortion occurs in the single electron spectrum, maximal at small electron energies. Then, we show that other LIV effects may be highlighted by analysing the angular correlation spectra and the ratio between the Standard Model Extension (SME) electron spectra and their Standard Model (SM) forms. We found that these LIV signatures depend on the magnitude of $a ˚_{of}^{(3)}$ , manifest differently for positive and negative values of this coefficient, and become more pronounced as the electron energy approaches the $Q$ -value. Finally, we propose an alternative, new method to constrain $a ˚_{of}^{(3)}$ through the measurement of the angular correlation coefficient. Using this method, and considering only statistical uncertainties, we obtain bounds of $a ˚_{of}^{(3)}$ at the level of present ones, obtained from summed energy spectra. We show that future experiments can improve these limits significantly. Our study is performed for $^{100}$ Mo, but the results hold qualitatively for other nuclei that undergo a double-beta decay. We hope our results will provide additional motivation for the LIV analyses performed in DBD experiments.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.05350 [pdf]
PRD(2021)·10 citations
05
[Submitted on 11 Sept 2020]
Neutron stars with Bogoliubov quark-meson coupling model
Aziz Rabhi🇵🇹 · Constança Providência🇵🇹 · Steven A. Moszkowski🇵🇹 · João da Providência🇵🇹 · Henrik Bohr🇩🇰
A quark-meson coupling model based on the quark model proposed by Bogoliubov for the description of the quark dynamics is developed and applied to the description of neutron stars. Starting from a su(3) symmetry approach, it is shown that this symmetry has to be broken in order to satisfy the constraints set by the hypernuclei and by neutron stars. The model is able to describe observations such as two solar mass stars or the radius of canonical neutron stars within the uncertainties presently accepted. If the optical potentials for $Λ$ and $Ξ$ hyperons in symmetric nuclear matter at saturation obtained from laboratory measurements of hypernuclei properties are imposed the model predicts no strangeness inside neutron stars.
Comments:
14 pages, 4 figures, 1 table, revised and re submitted for publication to Physical Review C journal
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2009.05370 [pdf]
PRC(2021)·2 citations
06
[Submitted on 10 Sept 2020]
Predictions for production of $_{Λ}^{3} H$ and $_{Λ}^{3} H$ in isobaric $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions at $s_{NN}$ = 200 GeV
Zhi-Lei She🇨🇳 · Gang Chen🇨🇳 · Dai-Mei Zhou🇨🇳 · Liang Zheng🇨🇳 · Yi-Long Xie🇨🇳 · Hong-Ge Xu🇨🇳
The production of $_{Λ}^{3} H$ and $_{Λ}^{3} H$ , as well as $^{3} H$ , $^{3} H$ , $^{3} He$ , and $^{3} He$ are studied in central collisions of isobars $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr at $s_{NN} = 200$ GeV, using the dynamically constrained phase-space coalescence model and the {\footnotesize PACIAE} model with chiral magnetic effect. The yield, yield ratio, coalescence parameters, and strangeness population factor of (anti-)hypertriton and (anti-)nuclei produced in isobaric $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions are predicted. The (anti-)hypertriton and (anti-)nuclei production is found to be insensitive to the chiral magnetic effects. Experimental data of Cu+Cu, Au+Au and Pb+Pb collisions from RHIC, LHC, and the results of {\footnotesize PACIAE+DCPC} model are presented in the results for comparison.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2009.05402 [pdf]
PRC(2021)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Formalism of hydrodynamics with spin degrees of freedom

Strangeness-changing Rates and Hyperonic Bulk Viscosity in Neutron Star Mergers

Impact of the neutron-star deformability on equation of state parameters

Probing Lorentz violation in 2νββ using single electron spectra and angular correlations

Neutron stars with Bogoliubov quark-meson coupling model

Predictions for production of Λ3​H and Λ3​H in isobaric 4496​Ru+4496​Ru and 4096​Zr+4096​Zr collisions at sNN​​ = 200 GeV

Affiliations

Probing Lorentz violation in $2 ν β β$ using single electron spectra and angular correlations

Predictions for production of $_{Λ}^{3} H$ and $_{Λ}^{3} H$ in isobaric $_{44}^{96}$ Ru+ $_{44}^{96}$ Ru and $_{40}^{96}$ Zr+ $_{40}^{96}$ Zr collisions at $s_{NN}$ = 200 GeV