Nuclear Theory·nucl-th

Monday·October 16, 2017

4 papers—4 primary·0 cross-listed

01
Quantified Gamow Shell Model interaction for $p s d$ -shell nuclei
Y. Jaganathen🇺🇸 · R. M. Id Betan🇦🇷 · N. Michel🇺🇸 · W. Nazarewicz🇺🇸 · M. Ploszajczak🇫🇷
The structure of weakly bound and unbound nuclei close to particle drip lines is one of the major science drivers of nuclear physics. A comprehensive understanding of these systems goes beyond the traditional configuration interactions approach formulated in the Hilbert space of localized states (nuclear shell model) and requires an open quantum system description. The complex-energy Gamow Shell Model (GSM) provides such a framework as it is capable of describing resonant and non-resonant many-body states on equal footing. To make reliable predictions, quality input is needed that allows for the full uncertainty quantification of theoretical results. In this study, we carry out the optimization of an effective GSM (one-body and two-body) interaction in the $p s df$ shell model space. The resulting interaction is expected to describe nuclei with $5 ⩽ A ⩽ 12$ at the $p - s d$ -shell interface. The optimized one-body potential reproduces nucleon- $^{4}$ He scattering phase shifts up to an excitation energy of 20 MeV. The two-body interaction built on top of the optimized one-body field is adjusted to the bound and unbound ground-state binding energies and selected excited states of the Helium, Lithium, and Beryllium isotopes up to $A = 9$ . A very good agreement with experiment was obtained for binding energies. First applications of the optimized interaction include predictions for two-nucleon correlation densities and excitation spectra of light nuclei with quantified uncertainties. The new interaction will enable comprehensive and fully quantified studies of structure and reactions aspects of nuclei from the $p s d$ region of the nuclear chart.
nucl-thPRC(2017)·79 citations
02
Light Neutron-Rich Hypernuclei from the Importance-Truncated No-Core Shell Model
Roland Wirth🇩🇪 · Robert Roth🇩🇪
We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from $_{Λ}^{5}$ He to $_{Λ}^{11}$ He and from $_{Λ}^{7}$ Li to $_{Λ}^{12}$ Li --- in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic variation with the regulator cutoff of the hyperon-nucleon interaction, the resulting neutron separation energies are very stable and in good agreement with available data for both nucleonic parents and their daughter hypernuclei. We provide predictions for the neutron separation energies and the spectra of neutron-rich hypernuclei that have not yet been observed experimentally. Furthermore, we find that the neutron drip lines in the helium and lithium isotopic chains are not changed by the addition of a hyperon.
nucl-thhep-phnucl-exPLB(2018)·57 citations
03
Fermi-momentum dependence of relativistic effective mass below saturation from superscaling of quasielastic electron scattering
V.L. Martinez-Consentino · I. Ruiz Simo · J.E. Amaro · E. Ruiz Arriola
The relativistic effective mass $M^{*}$ , and Fermi momentum, $k_{F}$ , are important ingredients in the determination of the nuclear equation of state, but they have rarely been extracted from experimental data below saturation density where translationally invariant nuclear matter becomes unstable against clusterization into the existing atomic nuclei. Using a novel kind of superscaling analysis of the quasielastic cross section electron scattering data involving a suitable selection criterion and $^{12}$ C as a reference nucleus, the global scaling properties of the resulting set of data for 21 nuclei ranging from $^{2}$ H to $^{238}$ U are then analyzed. We find that a subset of a third of the about $20000$ data approximately scales to an universal superscaling function with a more constrained uncertainty band than just the reference $^{12}$ C case and provides $M^{*}$ as a function of $k_{F}$ .
nucl-thPRC(2017)·18 citations
04
Neutrinoless double beta decay matrix elements in light nuclei
S. Pastore🇺🇸 · J. Carlson🇺🇸 · V. Cirigliano🇺🇸 · W. Dekens🇺🇸 · E. Mereghetti🇺🇸 · R.B. Wiringa🇺🇸
We present the first ab initio calculations of neutrinoless double beta decay matrix elements in $A = 6$ - $12$ nuclei using Variational Monte Carlo wave functions obtained from the Argonne $v_{18}$ two-nucleon potential and Illinois-7 three-nucleon interaction. We study both light Majorana neutrino exchange and potentials arising from a large class of multi-TeV mechanisms of lepton number violation. Our results provide benchmarks to be used in testing many-body methods that can be extended to the heavy nuclei of experimental interest. In light nuclei we have also studied the impact of two-body short range correlations and the use of different forms for the transition operators, such as those corresponding to different orders in chiral effective theory.
nucl-thhep-lathep-phPRC(2018)·88 citations

Affiliations

first authorsco-authorsvia INSPIRE

Quantified Gamow Shell Model interaction for psd-shell nuclei

Light Neutron-Rich Hypernuclei from the Importance-Truncated No-Core Shell Model

Fermi-momentum dependence of relativistic effective mass below saturation from superscaling of quasielastic electron scattering

Neutrinoless double beta decay matrix elements in light nuclei

Affiliations

Quantified Gamow Shell Model interaction for $p s d$ -shell nuclei