Nuclear Theory·nucl-th

Wednesday·June 27, 2018

6 papers—2 primary·4 cross-listed

01
[Submitted on 26 Jun 2018]
Reduced sensitivity of the $(d, p)$ cross sections to the deuteron model beyond adiabatic approximation
M. Gómez-Ramos🇪🇸 · N. K. Timofeyuk🇬🇧
It has recently been reported [Phys. Rev. Lett. 117, 162502 (2016)] that (d, p) cross sections can be very sensitive to the n-p interactions used in the adiabatic treatment of deuteron breakup with nonlocal nucleon-target optical potentials. To understand to what extent this sensitivity could originate in the inaccuracy of the adiabatic approximation we have developed a leading-order local- equivalent continuum-discretized coupled-channel model that accounts for non-adiabatic effects in the presence of nonlocality of nucleon optical potentials. We have applied our model to the astro- physically relevant reaction $^{26 m}$ Al $(d, p)^{27}$ Al using two different n-p potentials associated with the lowest and the highest n-p kinetic energy in the short-range region of their interaction, respectively. Our calculations reveal a significant reduction of the sensitivity to the high n-p momenta thus confirming that it is mostly associated with theoretical uncertainties of the adiabatic approximation itself. The non-adiabatic effects in the presence of nonlocality were found to be stronger than those in the case of the local optical potentials. These results argue for extending the analysis of the $(d, p)$ reactions, measured for spectroscopic studies, beyond the adiabatic approximation.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1806.09877 [pdf]
PRC(2018)·15 citations
02
[Submitted on 25 Jun 2018]
Constraints on the equation of state from the stability condition of neutron stars
P.S. Koliogiannis🇬🇷 · Ch.C. Moustakidis🇬🇷
The stellar equilibrium and collapse, including mainly white dwarfs, neutron stars and supper massive stars, is an interplay between general relativistic effects and the equation of state of nuclear matter. In the present work, we use the Chandrasekhar criterion of stellar instability by employing a large number of realistic equations of state (EoS) of neutron star matter. We mainly focus on the critical point of transition from stable to unstable configuration. This point corresponds to the maximum neutron star mass configuration. We calculate, in each case, the resulting compactness parameter, $β = GM / c^{2} R$ , and the corresponding effective adiabatic index, $γ_{cr}$ . The role of the trial function $ξ (r)$ is presented and discussed in details. We found that it holds a model-independent relation between $γ_{cr}$ and $β$ . This statement is strongly supported by the large number of EoS and it is also corroborated by using analytical solutions of the Einstein's field equations. In addition, we present and discuss the relation between the maximum rotation rate and the adiabatic index close to the instability limit. Accurate observational measurements of the upper bound of the neutron star mass and the corresponding radius, in connection with the present predictions, may help to impose constraints on the high density part of the neutron star equation of state.
Comments:
15 pages, 1 table, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
arXiv:
1806.09999 [pdf]
Astrophys.Space Sci.(2019)·31 citations
03
[Submitted on 25 Jun 2018] (cross-list from hep-th)
Universal magnetoresponse in QCD and $N = 4$ SYM
Gergely Endrodi🇩🇪 · Matthias Kaminski🇺🇸 · Andreas Schafer🇩🇪 · Jackson Wu🇺🇸 · Laurence Yaffe🇺🇸
Using recent lattice data on the thermodynamics of QCD in the presence of a background magnetic field, we show that the ratio of transverse to longitudinal pressure exhibits, to good accuracy, a simple scaling behavior over a wide range of temperature and magnetic field, essentially depending only on the ratio $T / B$ . We compare this QCD response to the corresponding magnetoresponse in maximally supersymmetric Yang Mills theory. Given suitable calibrations defining the comparison, we find excellent agreement. This may be viewed as a further test of the applicability of holographic models for hot QCD.
Comments:
v2: fixed minor typos, published version; v1: 23 pages, 6 figures
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1806.09632 [pdf]
JHEP(2018)·25 citations
04
[Submitted on 25 Jun 2018] (cross-list from astro-ph.HE)
Californium-254 and kilonova light curves
Y. Zhu🇺🇸 · R. T. Wollaeger🇺🇸 · N. Vassh🇺🇸 · R. Surman🇺🇸 · T. M. Sprouse🇺🇸 · M. R. Mumpower🇺🇸 · P. Moller🇺🇸 · G. C. McLaughlin🇺🇸 · O. Korobkin🇺🇸 · T. Kawano🇺🇸 · P. J. Jaffke🇺🇸 · E. M. Holmbeck🇺🇸 and 4 other authors
Neutron star mergers offer unique conditions for the creation of the heavy elements and additionally provide a testbed for our understanding of this synthesis known as the $r$ -process. We have performed dynamical nucleosynthesis calculations and identified a single isotope, $^{254}$ Cf, which has a particularly high impact on the brightness of electromagnetic transients associated with mergers on the order of 15 to 250 days. This is due to the anomalously long half-life of this isotope and the efficiency of fission thermalization compared to other nuclear channels. We estimate the fission fragment yield of this nucleus and outline the astrophysical conditions under which $^{254}$ Cf has the greatest impact to the light curve. Future observations in the middle-IR which are bright during this regime could indicate the production of actinide nucleosynthesis.
Comments:
9 pages, 5 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
1806.09724 [pdf]
ApJL(2018)·102 citations
05
[Submitted on 26 Jun 2018] (cross-list from astro-ph.HE)
Neutron star properties from optimized chiral nuclear interactions
Domenico Logoteta🇮🇹 · Ignazio Bombaci🇮🇹
We adopt two- and three-body nuclear forces derived at the next-to-next-to-leading-order (N2LO) in the framework of effective chiral perturbation theory (ChPT) to calculate the equation of state (EOS) of $β$ -stable neutron star matter using the Brueckner--Hartree--Fock many-body approach. We use the recent optimized chiral two-body nuclear interaction at N2LO derived by \cite{ekstrom1} and two different parametrizations of the three-body N2LO interaction: the first one is fixed to reproduce the saturation point of symmetric nuclear matter while the second one is fixed to reproduce the binding energies of light atomic nuclei. We show that in the second case the properties of nuclear matter are not well determined whereas in the first case various empirical nuclear matter properties around the saturation density are well reproduced. We also calculate the nuclear symmetry energy $E_{sy m}$ as a function of the nucleonic density and compare our results with the empirical constraints obtained using the excitation energies of isobaric analog states in nuclei and the experimental data on the neutron skin thickness of heavy nuclei. We next calculate various neutron star properties and in particular the mass-radius and mass-central density relations. We find that the adopted interactions based on a fully microscopic framework, are able to provide an EOS which is consistent with the present data of measured neutron star masses and in particular with the mass $M = 2.01 \pm 0.04 M_{⊙}$ of the neutron star in PSR J0348+0432. We finally consider the possible presence of hyperons in the stellar core and we find a softening of the EOS and a substantial reduction of the stellar maximum mass in agreement with similar calculations present in the literature.
Comments:
Accepted for publication in PASA
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
1806.09969 [pdf]
0 citations
06
[Submitted on 26 Jun 2018] (cross-list from hep-ph)
QCD determination of the magnetic field dependence of QCD and hadronic parameters
C. A. Dominguez🇿🇦 · M. Loewe🇿🇦 · Cristian Villavicencio🇨🇱
A set of four Finite Energy QCD sum rules are used to determine the magnetic field dependence of the sum of the up- and down-quark masses of QCD, $(m_{u} + m_{d})$ , the pion decay constant $f_{π}$ , the pion mass $m_{π}$ , the gluon condensate, $⟨ 0∣ α_{s} G^{2} ∣0 ⟩$ , and the squared energy threshold for the onset of perturbative QCD, $s_{0}$ , related to the Polyakov loop of lattice QCD.
Comments:
11 pages, 10 figures, version to appear in Physical Review D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1806.10088 [pdf]
PRD(2018)·29 citations

Affiliations

first authorsco-authorsvia INSPIRE

Reduced sensitivity of the (d,p) cross sections to the deuteron model beyond adiabatic approximation

Constraints on the equation of state from the stability condition of neutron stars

Universal magnetoresponse in QCD and N=4 SYM

Californium-254 and kilonova light curves

Neutron star properties from optimized chiral nuclear interactions

QCD determination of the magnetic field dependence of QCD and hadronic parameters

Affiliations

Reduced sensitivity of the $(d, p)$ cross sections to the deuteron model beyond adiabatic approximation

Universal magnetoresponse in QCD and $N = 4$ SYM