Kristina D. Launey
Louisiana State University
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Featured researches published by Kristina D. Launey.
Physics Letters B | 2013
A C Dreyfuss; Kristina D. Launey; T. Dytrych; J. P. Draayer; C. Bahri
Abstract By using only a fraction of the model space extended beyond current no-core shell-model limits and a many-nucleon interaction with a single parameter, we gain additional insight within a symmetry-guided shell-model framework, into the many-body dynamics that gives rise to the ground state rotational band together with phenomena tied to alpha-clustering substructures in the low-lying states in 12C, and in particular, the challenging Hoyle state and its first 2 + and 4 + excitations. For these states, we offer a novel perspective emerging out of no-core shell-model considerations, including a discussion of associated nuclear deformation and matter radii. This, in turn, provides guidance for ab initio shell models by informing key features of nuclear structure and the interaction.
Physical Review Letters | 2013
T. Dytrych; Kristina D. Launey; J. P. Draayer; Pieter Maris; James P. Vary; Erik Saule; Masha Sosonkina; Daniel Langr; M. A. Caprio
Results for ab initio no-core shell model calculations in a symmetry-adapted SU(3)-based coupling scheme demonstrate that collective modes in light nuclei emerge from first principles. The low-lying states of 6Li, 8Be, and 6He are shown to exhibit orderly patterns that favor spatial configurations with strong quadrupole deformation and complementary low intrinsic spin values, a picture that is consistent with the nuclear symplectic model. The results also suggest a pragmatic path forward to accommodate deformation-driven collective features in ab initio analyses when they dominate the nuclear landscape.
Physical Review C | 2012
Xin Guan; Kristina D. Launey; Mingxia Xie; Lina Bao; Feng Pan; J. P. Draayer
A new approach for solving the Bethe ansatz (Gaudin-Richardson) equations of the standard pairing problem is established based on the Heine-Stieltjes correspondence. For k pairs of valence nucleons on n different single-particle levels, it is found that solutions of the Bethe ansatz equations can be obtained from one (k + 1) ×(k + 1) and one (n 1)×(k + 1) matrices, which are associated with the extended Heine-Stieltjes and Van Vleck polynomials, respectively. Since the coefficients in these polynomials are free from divergence with variations in contrast to the original Bethe ansatz equations, the approach thus provides with a new efficient andsystematic way to solve the problem, which, by extension, can also be used to solve a large class of Gaudin-type quantum many-body problems and to establish a new efficient angular momentum projection method for multi-particle systems.
Physical Review C | 2014
G.K. Tobin; C. Bahri; J. P. Draayer; A C Dreyfuss; Kristina D. Launey; M.C. Ferriss; T. Dytrych
We present a microscopic description of nuclei in an intermediate-mass region, including the proximity to the proton drip line, based on a no-core shell model with a schematic many-nucleon long-range interaction with no parameter adjustments. The outcome confirms the essential role played by the symplectic symmetry to inform the interaction and the winnowing of shell-model spaces. We show that it is imperative that model spaces be expanded well beyond the current limits up through fifteen major shells to accommodate particle excitations that appear critical to highly-deformed spatial structures and the convergence of associated observables.
Progress in Particle and Nuclear Physics | 2016
Kristina D. Launey; T. Dytrych; J. P. Draayer
Abstract In this review, we present a symmetry-guided strategy that utilizes exact as well as partial symmetries for enabling a deeper understanding of and advancing ab initio studies for determining the microscopic structure of atomic nuclei. These symmetries expose physically relevant degrees of freedom that, for large-scale calculations with QCD-inspired interactions, allow the model space size to be reduced through a very structured selection of the basis states to physically relevant subspaces. This can guide explorations of simple patterns in nuclei and how they emerge from first principles, as well as extensions of the theory beyond current limitations toward heavier nuclei and larger model spaces. This is illustrated for the ab initio symmetry-adapted no-core shell model (SA-NCSM) and two significant underlying symmetries, the symplectic Sp ( 3 , R ) group and its deformation-related SU ( 3 ) subgroup. We review the broad scope of nuclei, where these symmetries have been found to play a key role—from the light p -shell systems, such as 6 Li, 8 B, 8 Be, 12 C, and 16 O, and s d -shell nuclei exemplified by 20 Ne, based on first-principle explorations; through the Hoyle state in 12 C and enhanced collectivity in intermediate-mass nuclei, within a no-core shell-model perspective; up to strongly deformed species of the rare-earth and actinide regions, as investigated in earlier studies. A complementary picture, driven by symmetries dual to Sp ( 3 , R ) , is also discussed. We briefly review symmetry-guided techniques that prove useful in various nuclear-theory models, such as Elliott model, ab initio SA-NCSM, symplectic model, pseudo- SU ( 3 ) and pseudo-symplectic models, ab initio hyperspherical harmonics method, ab initio lattice effective field theory, exact pairing–plus–shell model approaches, and cluster models, including the resonating-group method. Important implications of these approaches that have deepened our understanding of emergent phenomena in nuclei, such as enhanced collectivity, giant resonances, pairing, halo, and clustering, are discussed, with a focus on emergent patterns in the framework of the ab initio SA-NCSM with no a priori assumptions.
Physical Review C | 2015
T. Dytrych; A. C. Hayes; Kristina D. Launey; J. P. Draayer; Pieter Maris; James P. Vary; Daniel Langr; Tomáš Oberhuber
We present an ab initio symmetry-adapted no-core shell-model description for
Computer Physics Communications | 2016
T. Dytrych; Pieter Maris; Kristina D. Launey; J. P. Draayer; James P. Vary; Daniel Langr; Erik Saule; M. A. Caprio; Masha Sosonkina
^{6}
International Journal of Modern Physics E-nuclear Physics | 2015
Kristina D. Launey; J. P. Draayer; T. Dytrych; G.-H. Sun; Shishan Dong
Li. We study the structure of the ground state of
Journal of Physics: Conference Series | 2014
Kristina D. Launey; A C Dreyfuss; J. P. Draayer; T. Dytrych; Robert Baker
^{6}
Journal of Physics: Conference Series | 2011
J. P. Draayer; T. Dytrych; Kristina D. Launey
Li and the impact of the symmetry-guided space selection on the charge density components for this state in momentum space, including the effect of higher shells. We accomplish this by investigating the electron scattering charge form factor for momentum transfers up to