Nuclear Theory·nucl-th

Tuesday·May 3, 2016

13 papers—9 primary·4 cross-listed

01
Electric dipole moment of the deuteron in the standard model with $N N - Λ N - Σ N$ coupling
Nodoka Yamanaka
We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $∣Δ S ∣ = 1$ interactions by taking into account the $N N - Λ N - Σ N$ channel coupling, which is an important nuclear level systematics. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v 18$ nuclear force and the $Y N$ potential which can reproduce the binding energies of $_{Λ}^{3}$ H, $_{Λ}^{3}$ He, and $_{Λ}^{4}$ He. The $∣Δ S ∣ = 1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $Y N$ interaction is small, and treating $Λ N$ and $Σ N$ channels as free is a good approximation for the EDM of the deuteron.
nucl-thhep-exhep-phnucl-exNPA(2017)·27 citations
02
First clear evidence of quantum chaos in the bound states of an atomic nucleus
L. Muñoz · R. A. Molina · J.M.G. Gómez · A. Heusler
We study the spectral fluctuations of the $^{208}$ Pb nucleus using the complete experimental spectrum of 151 states up to excitation energies of $6.20$ MeV recently identified at the Maier-Leibnitz-Laboratorium at Garching, Germany. For natural parity states the results are very close to the predictions of Random Matrix Theory (RMT) for the nearest-neighbor spacing distribution. A quantitative estimate of the agreement is given by the Brody parameter $ω$ , which takes the value $ω = 0$ for regular systems and $ω ≃ 1$ for chaotic systems. We obtain $ω = 0.85 \pm 0.02$ which is, to our knowledge, the closest value to chaos ever observed in experimental bound states of nuclei. By contrast, the results for unnatural parity states are far from RMT behavior. We interpret these results as a consequence of the strength of the residual interaction in $^{208}$ Pb, which, according to experimental data, is much stronger for natural than for unnatural parity states. In addition our results show that chaotic and non-chaotic nuclear states coexist in the same energy region of the spectrum.
nucl-thquant-phPRC(2017)·13 citations
03
Electromagnetic response of 12C: a first-principles calculation
A. Lovato🇺🇸 · S. Gandolfi🇺🇸 · J. Carlson🇺🇸 · Steven C. Pieper🇺🇸 · R. Schiavilla🇺🇸
The longitudinal and transverse electromagnetic response functions of $^{12}$ C are computed in a "first-principles" Green's function Monte Carlo calculation, based on realistic two- and three-nucleon interactions and associated one- and two-body currents. We find excellent agreement between theory and experiment and, in particular, no evidence for the quenching of measured versus calculated longitudinal response. This is further corroborated by a re-analysis of the Coulomb sum rule, in which the contributions from the low-lying $J^{π}$ = $2^{+}$ , $0_{2}^{+}$ (Hoyle), and $4^{+}$ states in $^{12}$ C are accounted for explicitly in evaluating the total inelastic strength.
nucl-thhep-exPRL(2016)·120 citations
04
Isospin decomposition of $γ N \to N^{*}$ transitions within a dynamical coupled-channels model
H. Kamano🇯🇵 · S. X. Nakamura🇯🇵 · T.-S. H. Lee🇺🇸 · T. Sato🇯🇵
By extending the dynamical coupled-channels analysis performed in our previous work [Phys. Rev. C 88, 035209 (2013)] to include the available data of photoproduction of pi meson off the neutron, the transition amplitudes for the photo-excitation of the neutron to nucleon resonances, gamma n --> N*, at the resonance pole positions are determined. The combined fits to the data for both the proton- and neutron-target reactions also revise our results for the resonance pole positions and the gamma p --> N* transition amplitudes. Our results allow an isospin decomposition of the gamma N --> N* transition amplitudes for the isospin I=1/2 N* resonances, which is necessary for testing hadron structure models and gives crucial inputs for constructing models of neutrino-induced reactions in the nucleon resonance region.
nucl-thhep-phPRC(2016)·77 citations
05
A ferro-deformation at the open quantum system with protons, Z = 8, neutrons, N = 20: 28O
Chang-Bum Moon
We offer a possibility that the nuclear system with protons, Z = 8 has a large deformation at neutrons, N = 20; 28O that is beyond the neutron drip line. According to our previous works [arXiv: 1604.05013, 1604.02786, 1604.01017], it is expected that the ferro-deformation would occur at Z = 8, N = 20 through a shape phase transition at N = 18 out of N =16. The shape transition can be explained in terms of isospin dependent spin-orbital interactions between neutrons in the d3/2 orbital and protons in the d5/2 orbital, by yielding both the neutron and the proton pseudo-shell configurations built on each combined subshells. We argue that such a large deformation at N = 18 would be responsible for the 26O to be unbound, leading to a ground state neutron emitter. The ferro-deformation is mapped on the nuclear chart such that is around the following critical proton, neutron coordinates, (Z, N); (64, 104), (40, 64), (20, 40), (8, 20). This configuration depicts a beautiful pattern coming from a harmonious order in the microscopic quantum world.
nucl-thnucl-ex2 citations
06
N3LO NN interaction adjusted to light nuclei in ab exitu approach
A. M. Shirokov🇺🇸 · I. J. Shin🇰🇷 · Y. Kim🇰🇷 · M. Sosonkina🇺🇸 · P. Maris🇺🇸 · J. P. Vary🇺🇸
We use phase-equivalent transformations to adjust off-shell properties of similarity renormalization group evolved chiral effective field theory NN interaction (Idaho N3LO) to fit selected binding energies and spectra of light nuclei in an ab exitu approach. We then test the transformed interaction on a set of additional observables in light nuclei to verify that it provides reasonable descriptions of these observables with an apparent reduced need for three- and many-nucleon interactions.
nucl-thPLB(2016)·141 citations
07
Theoretical study of the $α + d$ $\to$ $^{6}$ Li + $γ$ astrophysical capture process in a three-body model
E.M. Tursunov (INP, Tashkent) · A.S. Kadyrov (Curtin University) · S.A. Turakulov (INP, Tashkent) · I. Bray (Curtin University)
The astrophysical capture process $α + d$ $\to$ $^{6}$ Li + $γ$ is studied in a three-body model. The initial state is factorized into the deuteron bound state and the $α + d$ scattering state. The final nucleus $^{6}$ Li(1+) is described as a three-body bound state $α + n + p$ in the hyperspherical Lagrange-mesh method. The contribution of the E1 transition operator from the initial isosinglet states to the isotriplet components of the final state is estimated to be negligible. An estimation of the forbidden E1 transition to the isosinglet components of the final state is comparable with the corresponding results of the two-body model. However, the contribution of the E2 transition operator is found to be much smaller than the corresponding estimations of the two-body model. The three-body model perfectly matches the new experimental data of the LUNA collaboration with the spectroscopic factor 2.586 estimated from the bound-state wave functions of $^{6}$ Li and deuteron.
nucl-thastro-ph.SRPRC(2016)·29 citations
08
Strangeness in nuclear physics
A. Gal🇮🇱 · E.V. Hungerford🇺🇸 · D.J. Millener🇺🇸
Extensions of nuclear physics to the strange sector are reviewed, covering data and models of Lambda and other hypernuclei, multi-strange matter, and anti-kaon bound states and condensation. Past achievements are highlighted, present unresolved problems discussed, and future directions outlined.
nucl-thnucl-exRMP(2016)·545 citations
09
Neutrinos in Astrophysics and Cosmology
A.B. Balantekin (Wisconsin U., Madison)🇺🇸
Neutrinos play a crucial role in many aspects of astrophysics and cosmology. Since they control the electron fraction, or equivalently neutron-to-proton ratio, neutrino properties impact yields of r-process nucleosynthesis. Similarly the weak decoupling temperature in the Big Bang Nucleosynthesis epoch is exponentially dependent on the neutron-to-proton ratio. In these conference proceedings, I briefly summarize some of the recent work exploring the role of neutrinos in astrophysics and cosmology.
nucl-thAIP Conf.Proc.(2016)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE