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
06
[Submitted on 18 Mar 2020] (cross-list from hep-ph)
One-meson-loop NJL model: Effect of collective and noncollective excitations on the quark condensate at finite temperature
Renan Câmara Pereira🇵🇹 · Pedro Costa🇵🇹
We explore the effect of including quantum fluctuations in the two flavor Nambu $-$ Jona-Lasinio model at finite temperature. This is accomplished, in a symmetry preserving way, by including collective and noncollective modes in the one-meson-loop gap equation which originate from poles and branch cuts in the complex plane, respectively. The inclusion of a boson cutoff, $Λ_{b}$ , is necessary to regularize the meson-loop momenta. This new parameter is used to study the influence of going beyond the usual mean field approximation in the quark condensate. As the temperature increases, chiral symmetry tends to get restored, the collective modes melt and only noncollective modes contribute to the quark condensate. With the inclusion of such modes, the quark condensate at finite temperature has a different behavior than at mean field level that will be explored.
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.08430 [pdf]
PRD(2020)·7 citations
07
[Submitted on 18 Mar 2020] (cross-list from hep-lat)
Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass
C. Alexandrou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · S. Bacchio (The Cyprus Inst.)🇨🇾 · M. Constantinou (Temple Univ.)🇺🇸 · J. Finkenrath (The Cyprus Inst.)🇨🇾 · K. Hadjiyiannakou (Univ. of Cyprus & The Cyprus Inst.)🇨🇾 · K. Jansen (DESY-Zeuthen)🇩🇪 · G. Koutsou (The Cyprus Inst.)🇨🇾 · H. Panagopoulos (Univ. of Cyprus)🇨🇾 · G. Spanoudes (Univ. of Cyprus)🇨🇾
We evaluate the gluon and quark contributions to the spin of the proton using an ensemble of gauge configuration generated at physical pion mass. We compute all valence and sea quark contributions to high accuracy. We perform a non-perturbative renormalization for both quark and gluon matrix elements. We find that the contribution of the up, down, strange and charm quarks to the proton intrinsic spin is $\frac{1}{2} \sum_{q = u, d, s, c} Δ Σ^{q^{+}} = 0.191 (15)$ and to the total spin $\sum_{q = u, d, s, c} J^{q^{+}} = 0.285 (45)$ . The gluon contribution to the spin is $J^{g} = 0.187 (46)$ yielding $J = J^{q} + J^{g} = 0.473 (71)$ confirming the spin sum. The momentum fraction carried by quarks in the proton is found to be $0.618 (60)$ and by gluons $0.427 (92)$ , the sum of which gives $1.045 (118)$ confirming the momentum sum rule. All scale and scheme dependent quantities are given in the $MS$ scheme at 2 GeV.
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.08486 [pdf]
PRD(2020)·191 citations
08
[Submitted on 19 Mar 2020] (cross-list from nucl-ex)
Refined scenario of the collinear cluster tri-partition mode with the greatest yield
Yu.V. Pyatkov · D. V. Kamanin · Yu. M. Tchuvil'sky · A. A. Alexandrov · I. A. Alexandrova · Z. I. Goryainova · V. Malaza · E. A. Kuznetsova · A. O. Strekalovsky · O. V. Strekalovsky · Sh. Wyngaardt · V. E. Zhuchko
In our previous publications we discussed various manifestations of a new decay channel of the low excited heavy nuclei called collinear cluster tri-partition (CCT). The most populated CCT mode was revealed in the mass correlation distribution of fission fragments (FFs) as a local region ("bump") of increased yields below the loci linked to the conventional binary fission. The bump was dubbed "Ni-bump" because it is centered at the masses associated with the magic isotopes of Ni. Intriguing features of the CCT, especially high collinearity of the CCT partners and relatively high probability comparable with that typical for conventional ternary fission, have caused rather wide discussion. In the majority of dedicated publications, the FFs partitions from the Ni-bump have been analyzed from the different points of view. In our publications, we have underlined that Ni-bump manifests itself at the detectable level only in the spectrometer arm that faces the source backing. So far, this fact has been left beyond the scope of all known theoretical considerations, while the backing likely plays a crucial role in the observation of the CCT experimental pattern.
Comments:
11 pages, 7 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2003.08591 [pdf]
0 citations
09
[Submitted on 19 Mar 2020] (cross-list from astro-ph.HE)
The Boltzmann-radiation-hydrodynamics Simulations of Core-collapse Supernovae with Different Equations of State: the Role of Nuclear Composition and the Behavior of Neutrinos
Akira Harada · Hiroki Nagakura · Wakana Iwakami · Hirotada Okawa · Shun Furusawa · Kohsuke Sumiyoshi · Hideo Matsufuru · Shoichi Yamada
Using the Boltzmann-radiation-hydrodynamics code, which solves the Boltzmann equation for neutrino transport, we present the results of the simulations with the nuclear equations of state (EOSs) of Lattimer and Swesty (LS) and Furusawa and Shen (FS). We extend the simulation time of the LS model and conduct thorough investigations, though our previous paper briefly reported some of the results. Only the LS model shows the shock revival. This seems to originate from the nuclear composition: the different nuclear composition results in the different energy loss by photodissociation and hence the different strength of the prompt convection and the later neutrino-driven convection. The protoneutron star seen in the FS model is more compact than that in the LS model because the existence of multinuclear species softens the EOS. For the behavior of neutrinos, we examined the flux and the Eddington tensor of neutrinos. In the optically thick region, the diffusion of neutrinos and the dragging by the motion of matter determine the flux. In the optically thin region, the free-streaming determines it. The Eddington tensor is compared with that obtained from the M1-closure relation. The M1-closure scheme overestimates the contribution from the velocity-dependent terms in the semitransparent region.
Comments:
30 pages, 24 figures, 1 explosion, published in ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)
arXiv:
2003.08630 [pdf]
ApJ(2020)·36 citations

Affiliations

first authorsco-authorsvia INSPIRE