Nuclear Theory·nucl-th

Friday·February 7, 2020

13 papers—7 primary·6 cross-listed

08
[Submitted on 5 Feb 2020] (cross-list from astro-ph.SR)
Universality and Non-Universality in Distributed Nuclear Burning in Homogeneous Isotropic Turbulence
Yossef Zenati · Robert T. Fisher
Nuclear burning plays a key role in a wide range of astrophysical stellar transients, including thermonuclear, pair instability, and core collapse supernovae, as well as kilonovae and collapsars. Turbulence is now understood to also play a key role in these astrophysical transients. Here we demonstrate that turbulent nuclear burning may lead to large enhancements above the uniform background burning rate, since turbulent dissipation gives rise to temperature fluctuations, and in general the nuclear burning rates are highly sensitive to temperature. We derive results for the turbulent enhancement of the nuclear burning rate under the influence of strong turbulence in the distributed burning regime in homogeneous isotropic turbulence, using probability distribution function (PDF) methods. We demonstrate that the turbulent enhancement obeys a universal scaling law in the limit of weak turbulence. We further demonstrate that, for a wide range of key nuclear reactions, such as C $^{12}$ (O $^{16}$ , $α$ )Mg $^{24}$ and triple- $α$ , even relatively modest temperature fluctuations, of the order ten percent, can lead to enhancements of 1 - 3 orders of magnitude in the turbulent nuclear burning rate. We verify the predicted turbulent enhancement directly against numerical simulations, and find very good agreement. We also present an estimation for the onset of turbulent detonation initiation, and discuss implications of our results for the modeling of stellar transients.
Comments:
Submitted, comments welcome
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2002.01937 [pdf]
PRL(2023)·3 citations
09
[Submitted on 5 Feb 2020] (cross-list from nucl-ex)
Evolution of the N=20 and 28 Shell Gaps and 2-particle-2-hole states in the FSU Interaction
R. S. Lubna · K. Kravvaris · S. L. Tabor. Vandana Tripathi · E. Rubino · A. Volya
The FSU $s p s df p$ cross-shell interaction for the shell model was successfully fitted to a wide range of mostly intruder negative parity states of the $s d$ shell nuclei. This paper reports the application of the FSU interaction to systematically trace out the relative positions of the effective single-particle energies of the $0 f_{7/2}$ and $1 p_{3/2}$ orbitals, the evolution from normally ordered low-lying states to the "Island of Inversion" (IoI), and the behavior of a wide range of excited states with a $0 f_{7/2}$ proton and neutron coupled to maximum spin of $7ℏ$ . Above a proton number of about 13 the $0 f_{7/2}$ orbital lies below that of $1 p_{3/2}$ , which is considered normal ordering, but systematically at $Z = 10$ to $12$ the orbitals cross. The calculations reproduce well the 2p2h - 0p0h inversion in the configurations of nuclei inside the IoI, they reproduce the absolute binding energies and the transition to normal ordering as the proton number approaches that of the neutrons. The important role of $1 p_{3/2}$ neutron pairs in the IoI is also demonstrated. The calculations account well for the energies of the fully aligned states with 0, 1, or 2 individual $s d$ nucleon aligned in spin with the aligned $π 0 f_{7/2}$ - $ν 0 f_{7/2}$ pair and reproduce well their systematic variation with $A$ and number of aligned $s d$ nucleons. The results presented in this paper give hope for the predictive power of the FSU interaction for more exotic nuclei to be explored in near future.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2002.01991 [pdf]
PRResearch(2020)·49 citations
10
[Submitted on 5 Feb 2020] (cross-list from quant-ph)
Fixed-Point Quantum Circuits for Quantum Field Theories
Natalie Klco🇺🇸 · Martin J. Savage🇺🇸
Renormalization group ideas and effective operators are used to efficiently determine localized unitaries for preparing the ground states of non-interacting scalar field theories on digital quantum devices. With these methods, classically computed ground states in a small spatial volume can be used to determine operators for preparing the ground state in a beyond-classical quantum register, even for interacting scalar field theories. Due to the exponential decay of correlation functions and the double exponential suppression of digitization artifacts, the derived quantum circuits are expected to be relevant already for near-term quantum devices.
Comments:
9 pages, 3 figures
Subjects:
Quantum Physics (quant-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2002.02018 [pdf]
PRA(2020)·34 citations
11
[Submitted on 6 Feb 2020] (cross-list from physics.atom-ph)
Skyrme-type nuclear interaction as a tool for calculating the finite nuclear size correction to atomic energy levels and the bound-electron $g$ factor
Igor A. Valuev🇩🇪 · Zoltán Harman🇩🇪 · Christoph H. Keitel🇩🇪 · Natalia S. Oreshkina (Max-Planck-Institut für Kernphysik)🇩🇪
A state-of-the-art approach for calculating the finite nuclear size correction to atomic energy levels and the bound-electron $g$ factor is introduced and demonstrated for a series of highly charged hydrogen-like ions. Firstly, self-consistent mean-field calculations based on the Skyrme-type nuclear interaction are employed in order to produce a realistic nuclear proton distribution. In the second step, the obtained nuclear charge density is used to construct the potential of an extended nucleus, and the Dirac equation is solved numerically. The ambiguity in the choice of a Skyrme parametrization is supressed by fine-tuning of only one parameter of the Skyrme force in order to accurately reproduce the experimental values of nuclear radii in each particular case. The homogeneously charged sphere approximation, the two-parameter Fermi distribution and experimental nuclear charge distributions are used for comparison with our approach, and the uncertainties of the presented calculations are estimated. In addition, suppression of the finite nuclear size effect for the specific differences of $g$ factors is demonstrated.
Comments:
8 pages, 1 figure, 4 tables
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2002.02227 [pdf]
PRA(2020)·19 citations
12
[Submitted on 6 Feb 2020] (cross-list from hep-ph)
JIMWLK Evolution, Lindblad Equation and Quantum-Classical Correspondence
Ming Li🇺🇸 · Alex Kovner🇺🇸
In the Color Glass Condensate(CGC) effective theory, the physics of valence gluons with large longitudinal momentum is reflected in the distribution of color charges in the transverse plane. Averaging over the valence degrees of freedom is effected by integrating over classical color charges with some quasi probability weight functional $W [j]$ whose evolution with rapidity is governed by the JIMWLK equation. In this paper, we reformulate this setup in terms of effective quantum field theory on valence Hilbert space governed by the reduced density matrix $ρ^$ for hard gluons, which is obtained after properly integrating out the soft gluon "environment". We show that the evolution of this density matrix with rapidity in the dense and dilute limits has the form of Lindblad equation. The quasi probability distribution (weight) functional $W$ is directly related to the reduced density matrix $ρ^$ through the generalization of the Wigner-Weyl quantum-classical correspondence, which reformulates quantum dynamics on Hilbert space in terms of classical dynamics on the phase space. In the present case the phase space is non Abelian and is spanned by the components of transverse color charge density $j$ . The same correspondence maps the Lindblad equation for $ρ^$ into the JIMWLK evolution equation for $W$ .
Comments:
48 pages, 1 figure, revised version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2002.02282 [pdf]
JHEP(2020)·18 citations
13
[Submitted on 6 Feb 2020] (cross-list from hep-ph)
How does the $S_{11}$ $N^{*} (890)$ state emerge from a naive $K$ matrix fit?
Yao Ma🇨🇳 · Wen-Qi Niu🇨🇳 · Yu-Fei Wang🇩🇪 · Han-Qing Zheng🇨🇳
We give a pedagogical analysis on $K$ matrix models describing the $π N$ scattering amplitude, in $S_{11}$ channel at low energies. We show how the correct use of analyticity in the $s$ channel and crossing symmetry in $t$ and $u$ channels leads to a much improved analytic behavior in the negative $s$ region, in agreement with the prediction from chiral perturbation amplitudes in its validity region. The analysis leads again to the conclusion that a genuine $N^{*} (890)$ resonance exists.
Comments:
9pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2002.02351 [pdf]
Commun.Theor.Phys.(2020)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Universality and Non-Universality in Distributed Nuclear Burning in Homogeneous Isotropic Turbulence

Evolution of the N=20 and 28 Shell Gaps and 2-particle-2-hole states in the FSU Interaction

Fixed-Point Quantum Circuits for Quantum Field Theories

Skyrme-type nuclear interaction as a tool for calculating the finite nuclear size correction to atomic energy levels and the bound-electron g factor

JIMWLK Evolution, Lindblad Equation and Quantum-Classical Correspondence

How does the S11​ N∗(890) state emerge from a naive K matrix fit?

Affiliations

Skyrme-type nuclear interaction as a tool for calculating the finite nuclear size correction to atomic energy levels and the bound-electron $g$ factor

How does the $S_{11}$ $N^{*} (890)$ state emerge from a naive $K$ matrix fit?