Nuclear Theory·nucl-th

Friday·March 20, 2020

9 papers—5 primary·4 cross-listed

01
[Submitted on 18 Mar 2020]
Lattice QCD Inputs for Nuclear Double Beta Decay
Vincenzo Cirigliano🇺🇸 · William Detmold🇺🇸 · Amy Nicholson🇺🇸 · Phiala Shanahan🇺🇸
Second order beta-decay processes with and without neutrinos in the final state are key probes of nuclear physics and of the nature of neutrinos. Neutrinoful double-beta decay is the rarest Standard Model process that has been observed and provides a unique test of the understanding of weak nuclear interactions. Observation of neutrinoless double-beta decay would reveal that neutrinos are Majorana fermions and that lepton number conservation is violated in nature. While significant progress has been made in phenomenological approaches to understanding these processes, establishing a connection between these processes and the physics of the Standard Model and beyond is a critical task as it will provide input into the design and interpretation of future experiments. The strong-interaction contributions to double-beta decay processes are non-perturbative and can only be addressed systematically through a combination of lattice Quantum Chromoodynamics (LQCD) and nuclear many-body calculations. In this review, current efforts to establish the LQCD connection are discussed for both neutrinoful and neutrinoless double-beta decay. LQCD calculations of the hadronic contributions to the neutrinoful process $nn \to pp e^{-} e^{-} ν ˉ_{e} ν ˉ_{e}$ and to various neutrinoless pionic transitions are reviewed, and the connections of these calculations to the phenomenology of double-beta decay through the use of effective field theory (EFTs) is highlighted. At present, LQCD calculations are limited to small nuclear systems, and to pionic subsystems, and require matching to appropriate EFTs to have direct phenomenological impact. However, these calculations have already revealed qualitatively that there are terms in the EFTs that can only be constrained from double-beta decay processes themselves or using inputs from LQCD. Future prospects for direct calculations in larger nuclei are also discussed.
Comments:
53 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2003.08493 [pdf]
PPNP(2020)·40 citations
02
[Submitted on 19 Mar 2020]
Challenge for describing the cluster states starting with realistic interaction
Naoyuki Itagaki · Tokuro Fukui · Akihiro Tohsaki
We aim to describe the cluster states of nuclear systems starting with a realistic interaction, which is a challenge of modern nuclear theories. Here, the short-range correlation of realistic interaction is treated by employing the damping factor, and the resultant interaction can be applied to the cluster structure of light nuclei. We start with a realistic interaction (G3RS) and transform it in this way, and the $α$ - $α$ energy curve is compared with the results of phenomenological interactions. The attractive effect between two $α$ 's is found to be not enough even with a damping factor for the short-range repulsion, and the necessity of a finite-range three-body term is discussed. With this three-body term, the resonance energy of the ground state and the scattering phase shift of two $α$ 's can be reproduced. Also, the binding energy of $^{16}$ O from the four $α$ threshold is reasonably reproduced. The linear-chain structure of three and four $α$ clusters in $^{12}$ C and $^{16}$ O are calculated with this interaction and compared with the results of the conventional approaches including the density functional theories.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2003.08546 [pdf]
2 citations
03
[Submitted on 19 Mar 2020]
The Continuum Spectrum of Hypernuclear Trios
M. Schäfer🇨🇿 · B. Bazak🇮🇱 · N. Barnea🇮🇱 · J. Mareš🇨🇿
The spectrum of hypernuclear trios composed of a $Λ$ baryon and two nucleons is the subject of an ongoing experimental campaign, aiming to study the interaction of the $Λ$ particle with a neutron, and the 3-body $Λ$ -nucleon-nucleon force. In this manuscript we utilize baryonic effective field theory at leading order, constrained to reproduce the available low energy light hypernuclear data, to study the continuum spectrum of such hypernuclear trios. Using the complex scaling method and the inverse analytic continuation in the coupling constant method we find the existence of a virtual state in the $Λ n p$ $J^{π} = \frac{3}{2}^{+}$ channel, leading to cross-section enhancement near threshold. For the $Λ nn$ $J^{π} = \frac{1}{2}^{+}$ channel we predict a resonance state. Depending, however, on the value of the $Λ N$ scattering length, the resonance pole moves from the physical to the unphysical complex energy sheet within the experimental bounds.
Comments:
8 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2003.08636 [pdf]
PLB(2020)·24 citations
04
[Submitted on 19 Mar 2020]
New proximity potential for alpha decay for superheavy nuclei
H.C. Manjunatha · K.N. Sridhar
We have constructed new proximity function particularly for interaction between two superheavy nuclei based on the experimental alpha decay half-lives. The new proximity function is used to produce the alpha decay half-lives of superheavy nuclei whose experimental values are known. The new proximity function produces the alpha decay half-lives close to the experiments. Hence we can conclude that the new proximity function can be used to study the interaction between two superheavy nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.08653 [pdf]
0 citations
05
[Submitted on 19 Mar 2020]
On the E2 admixture in the deexcitation of the 229mTh isomer
F. F. Karpeshin · M. B. Trzhaskovskaya · L. F. Vitushkin
Latest experimental data on the properties of the 229Th nuclide isomer are analyzed. Deduced are the lifetime and the E2-fraction in its electromagnetic deexcitation, based on the latest experimental data concerning the isomer: its energy together with the magnetic and quadrupole moments.
Comments:
13 pages, 1 figure. Delivered as talks at the 676. WE-Heraeus-Seminar on Novel optical clocks in atoms and nuclei, July 9 - 12, 2018 at the Physikzentrum, Bad Honnef, Germany, and KVNO-2019, April 15 - 19 at IAA RAS, 2019, Saint-Petersburg, Russia
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.08655 [pdf]
1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Lattice QCD Inputs for Nuclear Double Beta Decay

Challenge for describing the cluster states starting with realistic interaction

The Continuum Spectrum of Hypernuclear Trios

New proximity potential for alpha decay for superheavy nuclei

On the E2 admixture in the deexcitation of the 229mTh isomer

Affiliations