Nuclear Theory·nucl-th

Monday·July 18, 2022

9 papers—4 primary·5 cross-listed

01
[Submitted on 15 Jul 2022]
Collective model for cluster motion in $^{8}$ Be, $^{12}$ C, and $^{16}$ O systems
Yoshiko Kanada-En'yo · Nobuo Hinohara
A microscopic $n α$ cluster model was applied to $^{8}$ Be, $^{12}$ C, and $^{16}$ O systems to investigate cluster motion in the ground state and radial excitation. In the microscopic calculation of $^{12}$ C and $^{16}$ O using the generator coordinate method with the coordinate $D$ of the $α$ - $α$ distance, excited states were obtained as the large-amplitude mode built on the ground state. A collective model was constructed to describe the cluster motion of these states by utilizing inputs from the microscopic cluster model such as the norm kernel and energy expectation values. Furthermore, the cluster model was extended by introducing the imaginary part of the coordinate $D$ to incorporate the dynamical effects on the collective mass. The collective wave function obtained with the collective model was found to be in reasonable agreement with the results of the generator coordinate method for energies, root-mean-square radii, and amplitude functions.
Comments:
13pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2207.07239 [pdf]
PRC(2022)·2 citations
02
[Submitted on 15 Jul 2022]
Path Integral Quantum Monte Carlo Method for Light Nuclei
Rong Chen🇺🇸
I describe the first continuous space nuclear path integral quantum Monte Carlo method, and calculate the ground state properties of light nuclei including Deuteron, Triton, Helium-3 and Helium-4, using both local chiral interaction up to next-to-next-to-leading-order and the Argonne $v_{6}^{'}$ interaction. Compared with diffusion based quantum Monte Carlo methods such as Green's function Monte Carlo and auxiliary field diffusion Monte Carlo, path integral quantum Monte Carlo has the advantage that it can directly calculate the expectation value of operators without tradeoff, whether they commute with the Hamiltonian or not. For operators that commute with the Hamiltonian, e.g., the Hamiltonian itself, the path integral quantum Monte Carlo light-nuclei results agree with Green's function Monte Carlo and auxiliary field diffusion Monte Carlo results. For other operator expectations which are important to understand nuclear measurements but do not commute with the Hamiltonian and therefore cannot be accurately calculated by diffusion based quantum Monte Carlo methods without tradeoff, the path integral quantum Monte Carlo method gives reliable results. I show root-mean-square radii, one-particle number density distributions, and Euclidean response functions for single-nucleon couplings. I also systematically describe all the sampling algorithms used in this work, the strategies to make the computation efficient, the error estimations, and the details of the implementation of the code to perform calculations. This work can serve as a benchmark test for future calculations of larger nuclei or finite temperature nuclear matter using path integral quantum Monte Carlo.
Comments:
Rong Chen's 2020 PhD thesis at Arizona State University, Tempe, Arizona, USA. PhD Advisor, Professor Kevin E. Schmidt
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2207.07246 [pdf]
0 citations
03
[Submitted on 15 Jul 2022]
SS-HORSE Extension of the No-Core Shell Model: Application to Resonances in $^{7} H e$
I. A. Mazur · I. J. Shin · Y. Kim · A. I. Mazur · A. M. Shirokov · P. Maris · J. P. Vary
Theoretical ab initio studies of resonances in the unbound $^{7} He$ nucleus are presented. We perform no-core shell model calculations with $N N$ interactions Daejeon16 and JISP16 and utilize the SS-HORSE method to calculate the $S$ matrix for two-body channels $n -^{6} He$ and $n -^{6} H e^{*}$ with $^{6} He$ respectively in the ground and excited $2^{+}$ states as well as for the four-body democratic decay channel $^{4} He + n + n + n$ . The resonant energies and widths areobtained by numerical location of the $S$ -matrix poles. We describe all experimentally known $^{7} He$ resonances and suggest an interpretation of an observed wide resonance of unknown spin-parity.
Comments:
10 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2207.07360 [pdf]
PRC(2022)·15 citations
04
[Submitted on 15 Jul 2022]
Low energy structures in nuclear reactions with 4n in the final state
Rimantas Lazauskas🇫🇷 · Emiko Hiyama🇯🇵 · Jaume Carbonell🇫🇷
We present a reaction model to describe the fast removal of the $α$ -particle core in $^{8}$ He nucleus with eventual emission of four neutrons. The obtained four neutron energy distributions allows to explain the sharp low energy peak observed by studying the missing mass spectra of four neutrons in [Nature Vol. 606, p. 678], as a consequence of dineutron-dineutron correlations.
Comments:
Accepted to PRL
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2207.07575 [pdf]
PRL(2023)·44 citations
05
[Submitted on 14 Jul 2022] (cross-list from hep-ph)
Jet Broadening in Flowing Matter -- Resummation
Carlota Andres🇫🇷 · Fabio Dominguez🇪🇸 · Andrey V. Sadofyev🇪🇸 · Carlos A. Salgado🇪🇸
In this work, we obtain the leading corrections to the jet momentum broadening distribution in a QCD medium arising from the transverse flow of the matter. We first derive the single-particle propagator of a highly energetic parton resumming its multiple interactions with the homogeneous flowing matter, explicitly keeping the leading subeikonal flow terms. Then, we use this propagator to obtain the jet broadening distribution and its leading moments. We show that this distribution becomes anisotropic in the presence of transverse flow, since its odd moments are generally non-zero and proportional to the transverse velocity of the medium. Finally, we evaluate several odd moments, which we compare to the corresponding results at first order in opacity, showing that accounting for multiple in-medium scatterings is essential to describe some observables in dense nuclear matter.
Comments:
29 pages, 2 figures, v2: journal version, references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.07141 [pdf]
PRD(2022)·51 citations
06
[Submitted on 15 Jul 2022] (cross-list from astro-ph.HE)
Impact of systematic nuclear uncertainties on composition and decay heat of dynamical and disk ejecta in compact binary mergers
I. Kullmann · S. Goriely · O. Just · A. Bauswein · H.-T. Janka
Theoretically predicted yields of elements created by the rapid neutron capture (r-) process carry potentially large uncertainties associated with incomplete knowledge of nuclear properties and approximative hydrodynamical modelling of the matter ejection processes. We present an in-depth study of the nuclear uncertainties by varying theoretical nuclear input models that describe the experimentally unknown neutron-rich nuclei. This includes two frameworks for calculating the radiative neutron capture rates and 14 different models for nuclear masses, $β$ -decay rates and fission properties. Our r-process nuclear network calculations are based on detailed hydrodynamical simulations of dynamically ejected material from NS-NS or NS-BH binary mergers plus the secular ejecta from BH-torus systems. The impact of nuclear uncertainties on the r-process abundance distribution and the early radioactive heating rate is found to be modest (within a factor of $\sim 20$ for individual $A > 90$ abundances and a factor of 2 for the heating rate). However, the impact on the late-time heating rate is more significant and depends strongly on the contribution from fission. We witness significantly larger sensitivity to the nuclear physics input if only a single trajectory is used compared to considering ensembles of $\sim$ 200-300 trajectories, and the quantitative effects of the nuclear uncertainties strongly depend on the adopted conditions for the individual trajectory. We use the predicted Th/U ratio to estimate the cosmochronometric age of six metal-poor stars and find the impact of the nuclear uncertainties to be up to 2 Gyr.
Comments:
28 pages, 24 figures, accepted to MNRAS
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2207.07421 [pdf]
MNRAS(2023)·40 citations
07
[Submitted on 15 Jul 2022] (cross-list from hep-ph)
Nature of the $X (6900)$ in partial wave decomposition of $J / ψ J / ψ$ scattering
Qi Zhou🇨🇳 · Di Guo🇨🇳 · Shi-Qing Kuang🇨🇳 · Qin-He Yang🇨🇳 · Ling-Yun Dai🇨🇳
In this letter, we perform partial wave decomposition on coupled-channel scattering amplitudes, $J / ψ J / ψ$ - $J / ψ ψ (2 S)$ - $J / ψ ψ (3770)$ , to study the resonance appears in these processes. Effective Lagrangians are used to describe the interactions of four charmed vector mesons, and the scattering amplitudes are calculated up to the next-to-leading order. Partial wave projections are performed, and unitarization is implemented by Padé approximation. Then we fit the amplitudes to the $J / ψ J / ψ$ invariant mass spectra measured by LHCb and determine the unknown couplings. The pole parameters of the $X (6900)$ are extracted as $M = 6861. 0_{- 8.8}^{+ 6.3}$ ~MeV and $Γ = 129. 0_{- 3.4}^{+ 5.6}$ ~MeV. Our analysis implies that its quantum number prefers to be $0^{++}$ . The pole counting rule and phase shifts show that it is a normal Breit-Wigner resonance and, hence, should be a compact tetraquark.
Comments:
6 pages, 4 figures. To be the same as the published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.07537 [pdf]
PRD(2022)·21 citations
08
[Submitted on 15 Jul 2022] (cross-list from hep-ph)
Target normal single-spin asymmetry in inclusive electron-nucleon scattering with two-photon exchange: Analysis using $1/ N_{c}$ expansion
J. L. Goity🇺🇸 · C. Weiss🇺🇸 · C. T. Willemyns🇧🇪
We calculate the target normal single-spin asymmetry caused by two-photon exchange in inclusive electron-nucleon scattering in the resonance region. Our analysis uses the $1/ N_{c}$ expansion of low-energy QCD and combines $N$ and $Δ$ intermediate and final states using the contracted $S U (4)$ spin-flavor symmetry. The normal spin asymmetry obtained in leading-order accuracy in $1/ N_{c}$ has magnitude $\sim 1 0^{- 2}$ and different sign in $e p$ and $e n$ scattering. It can be measured in electron scattering at lab energies $\sim$ 0.5-1.5 GeV and provides a clean probe of two-photon exchange dynamics.
Comments:
7 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2207.07588 [pdf]
PLB(2022)·5 citations
09
[Submitted on 15 Jul 2022] (cross-list from nucl-ex)
Systematic Trends of 0 $_{2}^{+}$ , 1 $_{1}^{-}$ , 3 $_{1}^{-}$ and 2 $_{1}^{+}$ Excited States in Even-Even Nuclei
B. Pritychenko · B. Singh · M. Verpelli
The spin and parity ( $J^{π}$ ) assignments in even-even nuclei were reviewed across the nuclear chart using the Evaluated Nuclear Structure Data File (ENSDF). The prevalence of 2 $_{1}^{+}$ first or lowest excited states is confirmed. The properties of 0 $_{2}^{+}$ , 1 $_{1}^{-}$ , and 3 $_{1}^{-}$ lowest excited states were reexamined using the ENSDF data evaluation procedures. The $J^{π}$ systematic trends and correlations between level quantum numbers and nuclear physics phenomena are discussed.
Comments:
39 pages, 6 figures, 4 tables. NP/A (2022)
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2207.07639 [pdf]
NPA(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE