Nuclear Theory·nucl-th

Thursday·June 8, 2023

8 papers—5 primary·3 cross-listed

01
Five-body calculation of $s$ -wave $n$ - $^{4}$ He scattering at next-to-leading order pionless effective field theory
Mirko Bagnarol · Martin Schäfer · Betzalel Bazak · Nir Barnea
We present the first five-body calculations of $s$ -wave $n$ - $^{4}$ He scattering within leading order and next-to-leading order (NLO) pionless effective field theory. Using an harmonic oscillator trap technique and pionless effective field theory fitted to just six well-established experimental parameters, we predict the $s$ -wave $n$ - $^{4}$ He phase shifts, scattering length $a_{n^{4} He}^{1/2} (NLO) = 2.47 (4 num.) (17 theor.) fm$ , and effective range $r_{n^{4} He}^{1/2} (NLO) = 1.384 (3 num.) (211 theor.) fm$ in agreement with experiment. The apparent cutoff independence of our results is used to estimate the theoretical errors coming as an integral part of our final results.
nucl-thPLB(2023)·20 citations
02
Nuclear mass predictions based on deep neural network and finite-range droplet model (2012)
To Chung Yiu · Haozhao Liang · Jenny Lee
A neural network with two hidden layers is developed for nuclear mass prediction, based on the finite-range droplet model (FRDM12). Different hyperparameters, including the number of hidden units, the choice of activation functions, the initializers, and the learning rates, are adjusted explicitly and systematically. The resulting mass predictions are achieved by averaging the predictions given by several different sets of hyperparameters with different regularizers and seed numbers. It can provide us not only the average values of mass predictions but also reliable estimations in the mass prediction uncertainties. The overall root-mean-square deviations of nuclear mass have been reduced from $0.603$ MeV for the FRDM12 model to $0.200$ MeV and $0.232$ MeV for the training set and validation set, respectively.
nucl-thnucl-exCPC(2024)·5 citations
03
Momentum Shell in Quarkyonic Matter from Explicit Duality: A Dual Model for Cold, Dense QCD
Yuki Fujimoto🇺🇸 · Toru Kojo🇯🇵 · Larry D. McLerran🇺🇸
We present a model of cold QCD matter that bridges nuclear and quark matter through the duality relation between quarks and baryons. The baryon number and energy densities are expressed as functionals of either the baryon momentum distribution, $f_{B}$ , or the quark distribution, $f_{Q}$ , which are subject to the constraints on fermions, $0 \leq f_{B, Q} \leq 1$ . The theory is ideal in the sense that the confinement of quarks into baryons is reflected in the duality relation between $f_{Q}$ and $f_{B}$ , while other possible interactions among quarks and baryons are all neglected. The variational problem with the duality constraints is formulated and we explicitly construct analytic solutions, finding two distinct regimes: A nuclear matter regime at low density and a Quarkyonic regime at high density. In the Quarkyonic regime, baryons underoccupy states at low momenta but form a momentum shell with $f_{B} = 1$ on top of a quark Fermi sea. Such a theory describes a rapid transition from a soft nuclear equation of state to a stiff Quarkyonic equation of state. At this transition, there is a rapid increase in the pressure.
nucl-thastro-ph.HEhep-phPRL(2024)·63 citations
04
The magnetic dual chiral density wave phase in a rotating cold quark matter
H. Mortazavi Ghalati🇮🇷 · N. Sadooghi🇮🇷
The effect of rotation on the formation of the magnetic dual chiral density wave (\MD) in a dense and magnetized cold quark matter is studied. This phase is supposed to exist in the extreme conditions prevailing, e.g., in a neutron star. These conditions are, apart from high densities and strong magnetic fields, a relatively large angular velocity. To answer the question of whether the rotation enhances or suppresses the formation of this phase, we first determine the effect of rotation on the energy dispersion relation of a fermionic system in the presence of a constant magnetic field and then focus on the thermodynamic potential of the model at low temperature $T$ and finite chemical potential $μ$ . The thermodynamic potential consists, in particular, of an anomalous part leading to certain topological effects. We show that in comparison with the nonrotating case, a term proportional to the angular velocity appears in this anomalous potential. We then solve the corresponding gap equations to the chiral and spatial modulation condensates, and study the dependence of these dynamical variables on the chemical potential ( $μ$ ), magnetic field ( $e B$ ), and angular velocity ( $Ω$ ). It turns out that the interplay between these parameters suppresses the formation of the \MD~phase in relevant regimes for cold neutron stars. This is interpreted as the manifestation of the inverse magnetorotational catalysis, which is also reflected in the phase portraits $e B$ - $μ$ , $e B$ - $Ω R$ , and $μ$ - $Ω R$ , explored in this work.
nucl-thhep-phPRD(2023)·12 citations
05
Structure Factors for Hot Neutron Matter from Ab Initio Lattice Simulations with High-Fidelity Chiral Interactions
Yuan-Zhuo Ma · Zidu Lin · Bing-Nan Lu · Serdar Elhatisari · Dean Lee · Ning Li · Ulf-G. Meißner · Andrew W. Steiner · Qian Wang
We present the first ab initio lattice calculations of spin and density correlations in hot neutron matter using high-fidelity interactions at next-to-next-to-next-to-leading order (N3LO) in chiral effective field theory. These correlations have a large impact on neutrino heating and shock revival in core-collapse supernovae and are encapsulated in functions called structure factors. Unfortunately, calculations of structure factors using high-fidelity chiral interactions were well out of reach using existing computational methods. In this work, we solve the problem using a computational approach called the rank-one operator (RO) method. The RO method is a general technique with broad applications to simulations of fermionic many-body systems. It solves the problem of exponential scaling of computational effort when using perturbation theory for higher-body operators and higher-order corrections. Using the RO method, we compute the vector and axial static structure factors for hot neutron matter as a function of temperature and density. The ab initio lattice results are in good agreement with virial expansion calculations at low densities but are more reliable at higher densities. Random phase approximation codes used to estimate neutrino opacity in core-collapse supernovae simulations can now be calibrated with ab initio lattice calculations.
nucl-thPRL(2024)·32 citations
06
Coupled-channel influence on the $a_{0} (1700/1800)$ line shape
N. N. Achasov🇷🇺 · G. N. Shestakov🇷🇺
The current situation with the recently discovered $a_{0} (1700/1800)$ resonance is very paradoxical: it is believed that $a_{0} (1700/1800)$ must be strongly coupled with two vector mesons, but there is no direct experimental confirmation of this yet. Based on the assumption that the $a_{0} (1700/1800)$ is a state similar to the four-quark state from the MIT bag, belonging to either the $9^{*}$ or the $36^{*}$ $q^{2} q ˉ^{2}$ multiplet, we analyze the influence of the strong $a_{0} (1700/1800)$ coupling to the vector channels $K^{*} K ˉ^{*}$ , $ρϕ$ , and $ρ ω$ on its line shape in the decay channels into pseudoscalar mesons $K K ˉ$ , $π η$ , and $π η^{'}$ . This effect depends on the location of the resonance mass $m_{a_{0}}$ relative to the nominal thresholds of vector channels. For example, if $m_{a_{0}} \approx 1700$ MeV, then the influence turns out to be hidden in a fairly wide range of coupling constants. On the whole, our analysis shows that, to confirm the presence of the strong $a_{0} (1700/1800)$ coupling to the vector channels, utterly required is the direct detection of the decays $a_{0} (1700/1800) \to K^{*} K ˉ^{*}$ , $ρϕ$ , $ρ ω$ . The appearance of even certain hints at the existence of these decays would make it possible to fundamentally advance in understanding the nature of the new $a_{0}$ state.
↳ hep-phhep-exnucl-exnucl-thPRD(2023)·9 citations
07
Binding energies of ground and isomeric states in neutron-rich ruthenium isotopes: measurements at JYFLTRAP and comparison to theory
M. Hukkanen🇫🇮 · W. Ryssens · P. Ascher🇫🇷 · M. Bender🇫🇷 · T. Eronen🇫🇮 · S. Grévy🇫🇷 · A. Kankainen🇫🇮 · M. Stryjczyk🇫🇮 · L. Al Ayoubi🇫🇮 · S. Ayet🇩🇪 · O. Beliuskina🇫🇮 · C. Delafosse🇫🇮 and 18 other authors
We report on precision mass measurements of $^{113, 115, 117}$ Ru performed with the JYFLTRAP double Penning trap mass spectrometer at the Accelerator Laboratory of University of Jyväskylä. The phase-imaging ion-cyclotron-resonance technique was used to resolve the ground and isomeric states in $^{113, 115}$ Ru and enabled for the first time a measurement of the isomer excitation energies, $E_{x} (^{113}$ Ru $^{m}) = 100.5 (8)$ keV and $E_{x} (^{115}$ Ru $^{m}) = 129 (5)$ keV. The ground state of $^{117}$ Ru was measured using the time-of-flight ion-cyclotron-resonance technique. The new mass-excess value for $^{117}$ Ru is around 36 keV lower and 7 times more precise than the previous literature value. With the more precise ground-state mass values, the evolution of the two-neutron separation energies is further constrained and a similar trend as predicted by the BSkG1 model is obtained up to the neutron number $N = 71$ .
↳ nucl-exnucl-thPRC(2023)·12 citations
08
Constraining nuclear parameters using Gravitational waves from f-mode Oscillations in Neutron Stars
Bikram Keshari Pradhan · Dhruv Pathak · Debarati Chatterjee
Gravitational waves (GW) emanating from unstable quasi-normal modes in Neutron Stars (NS) could be accessible with the improved sensitivity of the current GW detectors or with the next-generation GW detectors and, therefore, can be employed to study the NS interior. Assuming f-mode excitation in isolated pulsars with typical energy of pulsar glitches and considering potential f-mode GW candidates for A+ (upgraded LIGO detectors operating at 5th observation run design sensitivity) and Einstein Telescope (ET), we demonstrate the inverse problem of NS asteroseismology within a Bayesian formalism to constrain the nuclear parameters and NS Equation of State (EOS). We describe the NS interior within relativistic mean field formalism. Taking the example of glitching pulsars, we find that for a single event in A+ and ET, among the nuclear parameters, the nucleon effective mass ( $m^{*}$ ) within 90\% credible interval (CI) can be restricted within $10%$ and $5%$ , respectively. At the same time, the incompressibility ( $K$ ) and the slope of the symmetry energy ( $L$ ) are only loosely constrained. Considering multiple (10) events in A+ and ET, all the nuclear parameters are well constrained, especially $m^{*}$ , which can be constrained to 3\% and 2\% in A+ and ET, respectively. Uncertainty in the observables of a $1.4 M_{⊙}$ NS such as radius ( $R_{1.4 M_{⊙}}$ ), f-mode frequency ( $f_{1.4 M_{⊙}}$ ), damping time ( $τ_{1.4 M_{⊙}}$ ) and a few EOS properties including squared speed of sound ( $c_{s}^{2}$ ) are also estimated.
↳ astro-ph.HEgr-qcnucl-thApJ(2023)·27 citations

Affiliations

first authorsco-authorsvia INSPIRE