Nuclear Theory·nucl-th

Tuesday·June 25, 2024

10 papers—6 primary·4 cross-listed

01
[Submitted on 21 Jun 2024]
Stochastic fluctuations and the relaxation time in transient relativistic fluids
Gabriel S. Denicol🇧🇷 · Jorge Noronha🇺🇸
We argue that the ratio between the shear viscosity and the shear relaxation time, $η / τ_{π}$ , should be defined as a thermodynamic quantity obtained from the equal-time symmetric correlator of the shear-stress tensor. In kinetic theory, we show that this ratio does not depend on the type of interaction. Similarly, an exact expression for this ratio is obtained for holographic gauge theories. We also determine how stochastic fluctuations change $η / τ_{π}$ in transient relativistic hydrodynamics and show that thermal fluctuations do not spoil causality and stability.
Comments:
13 pages (including Appendix)
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2406.15569 [pdf]
PLB(2025)·3 citations
02
[Submitted on 23 Jun 2024]
Impact of reactor neutrino uncertainties on coherent scattering's discovery potential
Leendert Hayen🇫🇷
Nuclear power reactors are the most intense man-made source of antineutrino's and have long been recognized as promising sources for coherent elastic neutrino-nucleus scattering (CE $ν$ NS) studies. Its observation and the spectral shape of the associated recoil spectrum is sensitive to a variety of exotic new physics scenarios and many experimental efforts are underway. Within the context of the reactor antineutrino anomaly, which initially indicated eV-scale sterile neutrino's, the modeling of the reactor antineutrino spectrum has seen a significant evolution in the last decade. Even so, uncertainties remain due to a variety of nuclear structure effects, incomplete information in nuclear databases and fission dynamics complexities. Here, we investigate the effects of these uncertainties on one's ability to accurately distinguish new physics signals. For the scenarios discussed here, we find that reactor spectral uncertainties are similar in magnitude to the projected sensitivities pointing towards a need for $β$ spectroscopy measurements below the inverse $β$ decay threshold.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2406.16081 [pdf]
J.Phys.G(2025)·3 citations
03
[Submitted on 23 Jun 2024]
Multipole modes of excitation in tetrahedrally deformed neutron-rich Zr isotopes
Jie Zhao
The multipole modes of excitation for tetrahedrally deformed neutron-rich Zr isotopes are investigated using the quasiparticle finite amplitude method based on the covariant density functional theories. By employing the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel and a separable pairing interaction of finite range, it is observed that a distinct peak emerges at $ω = 9.0 - 10.0$ MeV in the isoscalar quadrupole $K = 0$ strength when $β_{32}$ distortion is considered for $^{110, 112}$ Zr. This peak is absent when the deformation is limited to axially symmetric octuple or spherical case. It also does not appears in neighboring axially quadrople or octupole deformed nuclei, thus can be viewed as an indicator for the tetrahedral shape.
Comments:
6 pages, 5 figures, accepted for publication in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2406.16100 [pdf]
PRC(2024)·4 citations
04
[Submitted on 23 Jun 2024]
Short-Range Correlations and Urca Process in Neutron Stars
Armen Sedrakian
Recent measurements of high-momentum correlated neutron-proton pairs at JLab suggest that the dense nucleonic component of the compact stars contains a fraction of high-momentum neutron-proton pairs that is not accounted for in the familiar Fermi-liquid theory of the neutron-proton fluid mixture. We compute the rate of the Urca process in compact stars taking into account the non-Fermi liquid contributions to the proton's spectral widths induced by short-range correlations. The Urca rate differs strongly from the Fermi-liquid prediction at low temperatures, in particular, the high threshold on the proton fraction precluding the Urca process in neutron stars is replaced by a smooth increase with the proton fraction. This observation may have a profound impact on the theories of cooling of compact stars.
Comments:
v3: added references and fixed typos. Matches the published version, 6 pages, 2 figures. v2: Typos fixed; v1: 5 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2406.16183 [pdf]
PRL(2024)·26 citations
05
[Submitted on 23 Jun 2024]
Monopole Excitation and Nuclear Compressibility: Present and Future Perspectives
J. C. Zamora · S. Giraud
Isoscalar giant resonances are nuclear collective excitations associated with the oscillation in phase of protons and neutrons according to a certain multipolarity $L$ . In particular, the isoscalar giant monopole resonance ( $L = 0$ ) is the strongest nuclear compression mode, and its excitation energy is directly related to the compression modulus for finite nuclei. Typically, microscopic calculations are utilized to establish a relationship between the experimental compression modulus and the nuclear incompressibility that is a crucial parameter of the equation of state for nuclear matter. The incompressibility of nuclear matter has been determined with an accuracy of 10 to 20\% using relativistic and non-relativistic microscopic models for describing the monopole distributions in $^{208}$ Pb and $^{90}$ Zr isotopes. However, the same theoretical models are not able to describe data for open-shell nuclei, such as those of tin and cadmium isotopes. In fact, only effective interactions with a softer nuclear-matter incompressibility are able to predict the centroid energy of monopole distributions for open-shell nuclei. An unified description of the monopole resonance in $^{208}$ Pb and other open-shell nuclei remains unsolved from the theory side. Most of this uncertainty is due to our poor knowledge of the symmetry energy, which is another essential component of the equation of state of nuclear matter. Therefore, new experimental data along isotopic chains covering a wide range in $N / Z$ ratios, including neutron-deficient and neutron-rich nuclei, are of paramount importance for determining both the nuclear-matter incompressibility and the symmetry energy more precisely.
Comments:
In Oxford Research Encyclopedia of Physics
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex)
arXiv:
2406.16217 [pdf]
2 citations
06
[Submitted on 24 Jun 2024]
Revisiting the nuclear magnetic octupole moment
Stavros Bofos · Theo J. Mertzimekis
The nuclear magnetic octupole moment is revisited as a potentially useful observable for nuclear structure studies. The magnetic octupole moment, $Ω$ , is examined in terms of the nuclear collective model including weak and strong coupling. Single-particle formulation is additionally considered in the overall comparison of theoretical predictions with available experimental data. Mirror nuclei symmetry is examined in terms of the magnetic octupole moment isoscalar and isovector terms. A full list of predictions for $Ω$ of odd-proton and odd-neutron nuclei in medium-heavy mass regimes of the nuclear chart is produced aiming at providing starting values for future experimental endeavors.
Comments:
Accepted for publication in Atomic Data Nuclear Data Tables (27 pages, 2 figures, 5 tables)
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2406.16429 [pdf]
Atom.Data Nucl.Data Tabl.(2024)·2 citations
07
[Submitted on 30 May 2024] (cross-list from nucl-ex)
$^{242 m}$ Am isomer yield in $^{243}$ Am $(n, 2 n)$ reaction
V.M. Maslov
The reaction 243 Am (n, 2n) populates the T of 16 hours ground state 242 g Am with J of 1 or the 242 m Am isomer state J of 5 with T of 141 years. The former state 242 g Am mostly beta decays to 242 Cm, or transmutes to 242 Pu via electron capture. The absolute yield of 242 g Am is compatible with the measured data, estimated by the alpha activity of 242 Cm by Norris in 1983. The branching ratio defined by the ratio of the populations of the lowest intrinsic states of 242 Am. Calculated yields of ground 242 g Am and isomer 242 m Am states of the residual nucleus 242 Am are used to predict the relative yield of isomer. These populations defined by the gamma decay of the excited states, described by the standard kinetic equation. The ordering of the low and high spin states is different in case of 236 Np and 242 Am nuclei, that explains different shapes of relative yields near the (n, 2n) reaction threshold, though the excitation energy dependences are similar. Data of 243 Am (n, F) at 5 MeV and 15 MeV by Drapchinsky in 2004, support calculated 243Am (n,xnf) prefission neutron contribution to prompt fission neutron spectra and calculated exclusive neutron spectra of 243 Am (n, 2n) feeding the 242 g Am and isomer 242 m Am states.
Comments:
arXiv admin note: substantial text overlap with arXiv:2405.18366
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2406.15445 [pdf]
0 citations
08
[Submitted on 23 Jun 2024] (cross-list from nucl-ex)
Measurement of the $^{12} C (e, e^{'})$ cross sections at $Q^{2} = 0.8 GeV^{2} / c^{2}$
M. Mihovilovič🇸🇮 · L. Doria🇩🇪 · P. Achenbach🇺🇸 · A. M. Ankowski🇵🇱 · S. Bacca🇩🇪 · D. Bosnar🇭🇷 · A. Denig🇩🇪 · M. O. Distler🇩🇪 · A. Esser🇩🇪 · I. Friščić🇭🇷 · C. Giusti🇮🇹 · M. Hoek🇩🇪 and 13 other authors
We present the findings of a study based on a new inelastic electron-scattering experiment on the $^{12} C$ nucleus focusing on the kinematic region of $Q^{2} = 0.8 GeV^{2} / c^{2}$ . The measured cross section is sensitive to the transverse response function and provides a stringent test of theoretical models, as well as of the theoretical assumptions made in Monte-Carlo event-generator codes developed for the interpretation of neutrino-nucleus experiments, such as DUNE and HyperK. We find that modern generators such as GENIE and GiBUU reproduce our new experimental data within 10 $%$ .
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2406.16059 [pdf]
Few Body Syst.(2024)·11 citations
09
[Submitted on 23 Jun 2024] (cross-list from quant-ph)
Quantum computer specification for nuclear structure calculations
Ching-Hwa Wee🇲🇾 · Meng-Hock Koh🇲🇾 · Yung Szen Yap🇲🇾
Recent studies to solve nuclear structure problems using quantum computers rely on a quantum algorithm known as Variational Quantum Eigensolver (VQE). In this study, we calculate the correlation energy in Helium-6 using VQE, with a \textit{full-term} unitary-paired-coupled-cluster-doubles (UpCCD) ansatz on a quantum computer simulator and implement a set of custom termination criteria to shorten the optimization time. Using this setup, we test out noisy quantum computer simulators of various coherence times and quantum errors to find the required specification for such calculations. We also look into the contribution of errors from the quantum computers and optimization process. We find that the minimal specification of 5~ms coherence times and $1 0^{- 4}$ quantum errors is required to reliably reproduce state-vector results within 8\% discrepancy. Our study indicates the possibility of performing VQE calculations using a full-term UpCCD ansatz on a slightly noisy quantum computer, without implementing quantum error correction.
Comments:
9 pages, 4 figures, 1 table
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2406.16165 [pdf]
2 citations
10
[Submitted on 24 Jun 2024] (cross-list from hep-lat)
Scale setting and hadronic properties in light quark sector with $(2 + 1)$ -flavor Wilson fermions at the physical point
Tatsumi Aoyama (Tokyo U., ISSP)🇯🇵 · Takahiro M. Doi (Kyoto U. and Wako, RIKEN)🇯🇵 · Takumi Doi (Wako, RIKEN)🇯🇵 · Etsuko Itou (Kyoto U., Yukawa Inst., Kyoto and Wako, RIKEN)🇯🇵 · Yan Lyu (Wako, RIKEN)🇯🇵 · Kotaro Murakami (Tokyo Inst. Tech. and Wako, RIKEN)🇯🇵 · Takuya Sugiura (Rissho U. and Wako, RIKEN) (HAL QCD Collaboration)🇯🇵
We report scale setting and hadronic properties for our new lattice QCD gauge configuration set (HAL-conf-2023). We employ $(2 + 1)$ -flavor nonperturbatively improved Wilson fermions with stout smearing and the Iwasaki gauge action on a $9 6^{4}$ lattice, and generate configurations of 8,000 trajectories at the physical point. We show the basic properties of the configurations such as the plaquette value, topological charge distribution and their auto-correlation times. The scale setting is performed by detailed analyses of the $Ω$ baryon mass. We calculate the physical results of quark masses, decay constants of pseudoscalar mesons and single hadron spectra in light quark sector. The masses of the stable hadrons are found to agree with the experimental values within a sub-percent level.
Comments:
32 pages and 18 figures; v2: reference(s) added; v3: accepted for publication in Phys. Rev. D; v4: typo(s) corrected, published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2406.16665 [pdf]
PRD(2024)·25 citations

Affiliations

first authorsco-authorsvia INSPIRE