Nuclear Theory·nucl-th

Wednesday·September 15, 2021

11 papers—3 primary·8 cross-listed

04
[Submitted on 9 Sept 2021] (cross-list from astro-ph.HE)
Confirming the existence of twin stars in a NICER way
Jan-Erik Christian · Jürgen Schaffner-Bielich
We demonstrate that future radius measurement of the NICER mission have the potential to reveal the existence of a strong phase transition in dense neutron star matter by confirming the existence of so called twin stars, compact star configurations with the same mass but different radii. The latest radius constraints from NICER for the pulsars J0740+6620 as well as J0030+0451 are discussed using relativistic mean field equations of state with varying stiffness, connected with a first order phase transition to quark matter. We show, that twin star solutions are compatible with the new radius constraint but are located at radii \emph{below} the present constraints from NICER serving as a smoking gun for a strong phase transition in neutron star matter. This scenario is realized if a strong phase transition takes place in neutron stars of the first branch with masses above $2 M_{⊙}$ .
Comments:
5 pages, 3 figures. arXiv admin note: text overlap with arXiv:2011.01001
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2109.04191 [pdf]
ApJ(2022)·49 citations
05
[Submitted on 13 Sept 2021] (cross-list from hep-ph)
Neutrino interactions in liquid scintillators including active-sterile neutrino mixing
M.M.Saez🇦🇷 · M.E.Mosquera🇦🇷 · O.Civitarese🇦🇷
Neutrinos play an important role in core-collapse supernova events since they are a key piece to understand the explosion mechanisms. The analysis of the neutrino fluxes can bring answers to neutrino's related problems e.g.: mass hierarchy, spectral splitting, sterile neutrinos, etc. In this work we study the impact of neutrino oscillations and the possible existence of eV sterile neutrinos upon the supernova neutrino flux $F_{ν} (E)$ . We have calculated the energy distribution of the neutrino flux from a supernova and the total number of events which would be detected in a liquid scintillator. We also present an analysis for the conversion probabilities as a function of the active-sterile neutrino mixing parameters. Finally, we have carried out a statistical analysis to extract values for the mixing parameters of the model.
Comments:
20 pages, 11 figures, 74 references
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2109.06244 [pdf]
IJMPE(2022)·2 citations
06
[Submitted on 13 Sept 2021] (cross-list from hep-ph)
Hadrons as QCD Bound States
Paul Hoyer🇫🇮
Bound state perturbation theory is well established for QED atoms. Today the hyperfine splitting of Positronium is known to $O (α^{7} lo g α)$ . Whereas standard expansions of scattering amplitudes start from free states, bound states are expanded around eigenstates of the Hamiltonian including a binding potential. The eigenstate wave functions have all powers of $α$ , requiring a choice in the ordering of the perturbative expansion. Temporal $(A^{0} = 0)$ gauge permits an expansion starting from valence Fock states, bound by their instantaneous gauge field. This formulation is applicable in any frame and seems promising even for hadrons in QCD. The $O (α_{s}^{0})$ confining potential is determined (up to a universal scale) by a homogeneous solution of Gauss' law.
Comments:
7 pages, 1 figure. Talk at the (virtual) "Quark Confinement and the Hadron Spectrum 2021" conference on 2 -- 6 August 2021 in Stavanger, Norway
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2109.06257 [pdf]
EPJ Web Conf.(2022)·0 citations
07
[Submitted on 13 Sept 2021] (cross-list from hep-ph)
Machine-learning-based identification for initial clustering structure in relativistic heavy-ion collisions
Junjie He🇨🇳 · Wan-Bing He🇨🇳 · Yu-Gang Ma🇨🇳 · Song Zhang🇨🇳
$α$ -clustering structure is a significant topic in light nuclei. A Bayesian convolutional neural network (BCNN) is applied to classify initial non-clustered and clustered configurations, namely Woods-Saxon distribution and three- $α$ triangular (four- $α$ tetrahedral) structure for $^{12}$ C ( $^{16}$ O), from heavy-ion collision events generated within a multi-phase transport (AMPT) model. Azimuthal angle and transverse momentum distributions of charged pions are taken as inputs to train the classifier. On multiple-event basis, the overall classification accuracy can reach $95%$ for $^{12}$ C/ $^{16}$ O + $^{197}$ Au events at $S_{N N} =$ 200 GeV. With proper constructions of samples, the predicted deviations on mixed samples with different proportions of both configurations could be within $5%$ . In addition, setting a simple confidence threshold can further improve the predictions on the mixed dataset. Our results indicate promising and extensive possibilities of application of machine-learning-based techniques to real data and some other problems in physics of heavy-ion collisions.
Comments:
12 pages, 11 figures; Accepted by Physical Review C
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2109.06277 [pdf]
PRC(2021)·38 citations
08
[Submitted on 13 Sept 2021] (cross-list from nucl-ex)
Evidence for enhanced neutron-proton correlations from the level structure of the $N = Z + 1$ nucleus $_{43}^{87}$ Tc $_{44}$
X. Liu🇸🇪 · B. Cederwall🇸🇪 · C. Qi🇸🇪 · R. A. Wyss🇸🇪 · Ö. Aktas🇸🇪 · A. Ertoprak🇸🇪 · W. Zhang🇸🇪 · E. Clément🇫🇷 · G. de France🇫🇷 · D. Ralet🇫🇷 · A. Gadea🇪🇸 · A. Goasduff🇮🇹 and 60 other authors
The low-lying excited states in the neutron-deficient $N = Z + 1$ nucleus $_{43}^{87}$ Tc $_{44}$ have been studied via the fusion-evaporation reaction $^{54}$ Fe( $^{36}$ Ar, $2 n 1 p$ ) $^{87}$ Tc at the Grand Accélérateur National d'Ions Lourds (GANIL), France. The AGATA spectrometer was used in conjunction with the auxiliary NEDA, Neutron Wall, and DIAMANT detector arrays to measure coincident prompt $γ$ -rays, neutrons, and charged particles emitted in the reaction. A level scheme of $^{87}$ Tc from the (9/2 $_{g . s .}^{+}$ ) state to the (33/2 $_{1}^{+}$ ) state was established based on 6 mutually coincident $γ$ -ray transitions. The constructed level structure exhibits a rotational behavior with a sharp backbending at $ℏ ω \approx 0.50$ MeV. A decrease in alignment frequency and increase in alignment sharpness in the odd-mass isotonic chains around $N = 44$ is proposed as an effect of the enhanced isoscalar neutron-proton interactions in odd-mass nuclei when approaching the $N = Z$ line.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2109.06292 [pdf]
PRC(2021)·7 citations
09
[Submitted on 14 Sept 2021] (cross-list from hep-th)
Fluctuating relativistic dissipative hydrodynamics as a gauge theory
Travis Dore🇺🇸 · Lorenzo Gavassino🇵🇱 · David Montenegro🇧🇷 · Masoud Shokri🇮🇷 · Giorgio Torrieri🇧🇷
We argue that different formulations of hydrodynamics are related to uncertainties in the definitions of local thermodynamic and hydrodynamic variables. We show that this ambiguity can be resolved by viewing different formulations of hydrodynamics as particular "gauge choices" which lead to the same physical behavior of the system. Using the example of bulk viscosity, we show that Bemfica-Disconzi-Noronha-Kovtun (BDNK) and Israel-Stewart hydrodynamics are particular "gauge choices" of this type, related by a well-defined transformation of thermodynamic and hydrodynamic variables. We argue that this gauge ambiguity is necessary to ascertain the causality of stochastic hydrodynamic evolution and conjecture that it could explain the applicability of hydrodynamics outside its expected regime of validity since far from equilibrium and close to equilibrium may be related through transformations of this type.
Comments:
Version Accepted for publication, Annals of Physics
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2109.06389 [pdf]
Annals Phys.(2022)·46 citations
10
[Submitted on 14 Sept 2021] (cross-list from hep-ph)
Full solution of the medium-induced radiation spectrum
Carlota Andres🇺🇸 · Liliana Apolinario🇵🇹 · Fabio Dominguez🇪🇸
New measurements of jet quenching observables at RHIC and at the LHC, such as jet substructure observables, demand an increased precision in the theory calculations describing medium-induced radiation of gluons. Closed expressions for the gluon spectrum including a full resummation of multiple scatterings have been known for the past 20 years. Still they have only been evaluated in specific limits either taking a few terms in an opacity expansion or by employing a Gaussian approximation for the interaction potential -- which misses essential physical effects. We present here a new flexible method to compute the full spectrum for a realistic interaction potential, thus allowing us for the first time to properly quantify the effect of the all-order resummation of multiple scatterings. This new approach paves the way for precision phenomenological studies including multiple scattering effects such as coherence phenomena.
Comments:
Proceedings of Hard Probes 2020
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2109.06571 [pdf]
PoS(2021)·0 citations
11
[Submitted on 14 Sept 2021] (cross-list from astro-ph.HE)
Nonequilibrium thermodynamics of accreted neutron-star crust
Mikhail E. Gusakov · Elena M. Kantor · Andrey I. Chugunov
We show that, in order to determine the equation of state of the inner crust of an accreting neutron star, one should minimize not the Gibbs free energy, as it is generally assumed in the literature, but a different thermodynamic potential $Ψ$ , which tends to the minimum at fixed pressure and neutron chemical potential. Once this potential is specified, one can calculate the heat-release distribution in the stellar crust due to nonequilibrium nuclear reactions induced by accretion of matter onto the neutron-star surface. The results are important for adequate modeling of the accreted crust and interpretation of the observations of accreting neutron stars in low-mass X-ray binaries.
Comments:
6 pages, accepted for publication in Phys. Rev. D (Letters)
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2109.06614 [pdf]
PRD(2021)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE