Nuclear Theory·nucl-th

Wednesday·December 2, 2020

8 papers—3 primary·5 cross-listed

01
[Submitted on 1 Dec 2020]
Ab initio framework for nuclear scattering and reactions induced by light projectiles
Konstantinos Kravvaris🇺🇸 · Sofia Quaglioni🇺🇸 · Guillaume Hupin🇫🇷 · Petr Navratil🇨🇦
A quantitative and predictive microscopic theoretical framework that can describe reactions induced by $α$ particles ( $^{4}$ He nuclei) and heavier projectiles is currently lacking. Such a framework would contribute to reducing uncertainty in the modeling of stellar evolution and nucleosynthesis and provide the basis for achieving a comprehensive understanding of the phenomenon of nuclear clustering (the organization of protons and neutrons into distinct substructures within a nucleus). We have developed an efficient and general configuration-interaction framework for the description of low-energy reactions and clustering in light nuclei. The new formalism takes full advantage of powerful second-quantization techniques, enabling the description of $α$ - $α$ scattering and an exploration of clustering in the exotic $^{12}$ Be nucleus. We find that the $^{4}$ He( $α$ , $α$ ) $^{4}$ He differential cross section computed with non-locally regulated chiral interactions is in good agreement with experimental data. Our results for $^{12}$ Be indicate the presence of strongly mixed helium-cluster states consistent with a molecular-like picture surviving far above the $^{6}$ He+ $^{6}$ He threshold, and reveal the strong influence of neutron decay in both the $^{12}$ Be spectrum and in the $^{6}$ He( $^{6}$ He, $α$ ) $^{8}$ He cross section. We expect that this approach will enable the description of helium burning cross sections and provide insight on how three-nucleon forces influence the emergence of clustering in nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2012.00228 [pdf]
PLB(2024)·27 citations
02
[Submitted on 1 Dec 2020]
New Geiger-Nuttall law for two-proton radioactivity
Hong-Ming Liu · You-Tian Zou · Xiao Pan · Jiu-Long Chen · Biao He · Xiao-Hua Li
In the present work, combining with the Geiger-Nuttall law, a two-parameter empirical formula is proposed to study the two-proton (2p) radioactivity. Using this formula, the calculated 2p radioactivity half-lives are in good agreement with the experimental data as well as the calculated ones obtained by Goncalves et al: ([Phys. Lett. B 774, 14 (2017)]) using the effective liquid drop model (ELDM), Sreeja et al: ([Eur. Phys. J. A 55, 33 (2019)]) using a four-parameter empirical formula and Cui et al: ([Phys. Rev. C 101: 014301 (2020)]) using a generalized liquid drop model (GLDM). In addition, this two-parameter empirical formula is extended to predict the half-lives of 22 possible 2p radioactivity candidates, whose the 2p radioactivity released energy Q2p>0, obtained from the latest evaluated atomic mass table AME2016. The predicted results have good consistency with ones using other theoretical models such as the ELDM, GLDM and four-parameter empirical formula.
Comments:
6 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2012.00295 [pdf]
CPC(2021)·42 citations
03
[Submitted on 1 Dec 2020]
Estimate of the location of the neutron drip line for calcium isotopes from an exact Hamiltonian with continuum pair correlations
A. C. Dassie · R. M. Id Betan
The eastern region of the calcium isotope chain of the nuclei chart is, nowadays, of great activity. The experimental assessment of the limit of stability is of interest to confirm or improve microscopic theoretical models. The goal of this work is to provide the drip line of the calcium isotopes from the exact solution of the pairing Hamiltonian which incorporates explicitly the correlations with the continuum spectrum of energy. The modified Richardson equations, which include correlations with the continuum spectrum of energy modeled by the continuum single particle level density, is used to solve the many-body system. Three models are used, two isospin independent models with core 40Ca and 48Ca, and one isospin dependent model. One and two-neutron separation energies and occupation probabilities for bound and continuum states are calculated from the solution of the Richardson equations. The one particle drip line is found at the nucleus 57Ca, while the two neutron drip line is found at the nucleus 60Ca from the isospin independent model and at 66Ca from the isospin dependent one.
Comments:
9 pages, 14 figures, 63 references
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2012.00680 [pdf]
PRC(2020)·0 citations
04
[Submitted on 30 Nov 2020] (cross-list from hep-th)
Single-particle digitization strategy for quantum computation of a $ϕ^{4}$ scalar field theory
João Barata🇪🇸 · Niklas Mueller🇺🇸 · Andrey Tarasov🇺🇸 · Raju Venugopalan🇺🇸
Motivated by the parton picture of high energy quantum chromodynamics, we develop a single-particle digitization strategy for the efficient quantum simulation of relativistic scattering processes in a $d + 1$ dimensional scalar $ϕ^{4}$ field theory. We work out quantum algorithms for initial state preparation, time evolution and final state measurements. We outline a non-perturbative renormalization strategy in this single-particle framework.
Comments:
31 pages, 13 figures; journal version published in Phys. Rev. A 103, 042410 (2021); Table I modified to to include more precise estimate for cost of initial state preparation; Appendix B (discussion of state preparation) significantly extended & figures 10 and 11 added
Subjects:
High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2012.00020 [pdf]
PRA(2021)·85 citations
05
[Submitted on 30 Nov 2020] (cross-list from nucl-ex)
Anomalies in Radioactive Decay Rates: A Bibliography of Measurements and Theory
M. H. McDuffie · P. Graham · J. L. Eppele · J. T. Gruenwald · D. Javorsek II · D. E. Krause · E. Fischbach
Knowledge of the decay rates (or half-lives) of radioisotopes is critical in many fields, including medicine, archeology, and nuclear physics, to name just a few. Central to the many uses of radioisotopes is the belief that decay rates are fundamental constants of nature, just as the masses of the radioisotopes themselves are. Recently, the belief that decay rates are fundamental constants has been called into question following the observation of various reported anomalies in decay rates, such as apparent periodic variations. The purpose of this bibliography is to collect in one place the relevant literature on both sides of this issue in the expectation that doing so will deepen our understanding of the available data.
Comments:
30 pages, fixed hyperlink issue
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2012.00153 [pdf]
9 citations
06
[Submitted on 1 Dec 2020] (cross-list from gr-qc)
Scalar field quasinormal modes of noncommutative high dimensional Schwarzschild-Tangherlini black hole spacetime with smeared matter sources
Zening Yan🇨🇳 · Chen Wu🇨🇳 · Wenjun Guo🇨🇳
We investigate the massless scalar quasinormal modes (QNMs) of the noncommutative $D$ -dimensional Schwarzschild-Tangherlini black hole spacetime in this paper. By using the Wentzel-Kramers-Brillouin (WKB) approximation method, the asymptotic iterative method (AIM) and the inverted potential method (IPM) method, we made a detail analysis of the massless scalar QNM frequencies by varying the general smeared matter distribution and the allowable characteristic parameters ( $k$ and $θ$ ) corresponding to different dimensions. It is found that the nonconvergence of the high order WKB approximation exists in the QNMs frequencies of scalar perturbation around the noncommutative $D$ -dimensional Schwarzschild black holes. We conclude that the 3rd WKB result should be more reliable than those of the high order WKB method since our numerical results are also verified by the AIM method and the IPM method. In the dimensional range of $4 \leq D \leq 7$ , the scalar QNMs as a function of the different papameters (the noncommutative parameter $θ$ , the smeared matter distribution parameter $k$ , the multipole number $l$ and the main node number $n$ ) are obtained. Moreover, we study the dynamical evolution of a scalar field in the background of the noncommutative high dimensional Schwarzschild-Tangherlini black hole.
Comments:
26 pages, 11 figures, to be appeared in Nucl. phys. B
Subjects:
General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
arXiv:
2012.00320 [pdf]
NPB(2020)·21 citations
07
[Submitted on 1 Dec 2020] (cross-list from physics.atom-ph)
Atomic calculations of hyperfine structure anomaly in gold
Yu. A. Demidov · E. A. Konovalova · R. T. Imanbaeva · M. G. Kozlov · A. E. Barzakh
The magnetic hyperfine structure constants have been calculated for low-lying levels in neutral gold atom and gold-like ion of mercury taking into account Bohr--Weisskopf (BW) effect. BW effect is represented as a product of atomic and nuclear ( $d_{nuc}$ ) factors. We have calculated the atomic factors, which enable one to extract BW-correction values for far from stability gold nuclei from the experimental data. The possible uncertainty of our atomic calculations have been estimated by the comparison with the available experimental data. It has been shown that the standard single-particle approach in $d_{nuc}$ calculation reasonably well describes experimental data for $11/ 2^{-}$ gold isomers and $3/ 2^{+}$ ground state of $^{199} Au$ . At the same time, it fails to describe the hyperfine constant in $^{197} Au$ . This indicates the more pronounced configuration mixing in $^{197} Au$ than in $^{199} Au$ .
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2012.00401 [pdf]
PRA(2021)·6 citations
08
[Submitted on 1 Dec 2020] (cross-list from hep-ph)
Curing the unphysical behaviour of NLO quarkonium production at the LHC and its relevance to constrain the gluon PDF at low scales
Jean-Philippe Lansberg🇫🇷 · Melih Arslan Ozcelik🇫🇷
We address the unphysical energy dependence of quarkonium-hadroproduction cross sections at Next-to-Leading Order (NLO) in alpha_S which we attribute to an over-subtraction in the factorisation of the collinear singularities inside the PDFs in the MSbar scheme. Such over- or under-subtractions have a limited phenomenological relevance in most of the scattering processes in particle physics. On the contrary, it is particularly harmful for P_T-integrated charmonium hadroproduction which renders a wide class of NLO results essentially unusable. Indeed, in such processes, alphaS is not so small, the PDFs are not evolved much and can be rather flat for the corresponding momentum fractions and, finally, some process-dependent NLO pieces are either too small or too large. We propose a scale-fixing criterion which avoids such an over-subtraction. We demonstrate its efficiency for eta(c,b) but also for a fictitious light elementary scalar boson. Having provided stable NLO predictions for eta(c,b) P_T-integrated cross sections, sigma^NLO(eta(Q)), and discussed the options to study eta(b) hadroproduction, we argue that their measurement at the LHC can help better determine the gluon PDF at low scales and tell whether the local minimum in conventional NLO gluon PDFs around x=0.001 at scales below 2 GeV is physical or not.
Comments:
LaTeX, 23 pages, 58 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2012.00702 [pdf]
EPJC(2021)·34 citations

Affiliations

first authorsco-authorsvia INSPIRE