313 citations · 2k across the 83 of their papers we have counts for
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Quantum Theory Angular Momentum; Electronic version 2026
Niels R. Walet
This is an electronic version of the open source book "Quantum Theory of Angular Momentum" by D. A. Varshalovich, A. N. Moskalev, V. K. Khersonskii, original copyright \c{opyright}…
Calculation of Dynamical Response Functions Using a Bound-state Method
Niels R. Walet, Jagjit Singh, Johannes Kirscher +3
We investigate a method to extract response functions (dynamical polarisabilities) directly from a bound-state approach applied to calculations of perturbation-induced reactions. T…
Description of light nuclei in pionless effective field theory using the stochastic variational method
Vadim Lensky, Michael C. Birse, Niels R. Walet
We construct a coordinate-space potential based on pionless effective field theory with a Gaussian regulator. Charge-symmetry breaking is included through the Coulomb potential and…
Functional renormalisation group for few-nucleon systems: SU(4) symmetry and its breaking
Michael C. Birse, Boris Krippa, Niels R. Walet
We apply the functional renormalisation group to few-nucleon systems. Our starting point is a local effective action that includes three- and four-nucleon interactions, expressed i…
Shape mixing in the A 70 region
Daniel Almehed, Niels R. Walet
We investigate the mixing of different shapes in the A~70 region using the adiabatic self-consistent collective method in a rotating nuclei. The calculation is done for 68^Se and 7…
Removal of Spurious Admixture in a Self-consistent Theory of Adiabatic Large Amplitude Collective Motion
Toby D. Young, Niels R. Walet
In this article we analyse, for a simple model, the properties of a practical implementation of a fully self-consistent theory of adiabatic large-amplitude collective motion using…
Description of resonances in light nuclei using a microscopic cluster model
Theodoros Leontiou, Niels R. Walet
We investigate resonances in light halo nuclei using a fully microscopic cluster model and the complex scaling method. We make use of the hermitian representation of the complex sc…
Variational Monte Carlo for Microscopic Cluster Models
Theodoros Leontiou, Niels R. Walet
We examine the application of the Variational Monte Carlo (VMC) method to a cluster model for halo nuclei. Particular attention is paid to the error estimate in the presence of cor…
Oblate-prolate shape coexistence at finite angular momentum
Daniel Almehed, Niels R. Walet
We investigate shape coexistence in a rotating nucleus. We concentrate on the interesting case of 72-Kr which exhibits an interesting interplay between prolate and oblate states as…
Towards a practical approach for self-consistent large amplitude collective motion
Daniel Almehed, Niels R. Walet
We investigate the use of an operatorial basis in a self-consistent theory of large amplitude collective motion. For the example of the pairing-plus-quadrupole model, which has bee…
Off-shell effects and consistency of many-body treatments of dense matter
Boris Krippa, Michael C. Birse, Judith A. McGovern +1
Effective field theory requires all observables to be independent of the representation used for the quantum field operators. It means that off-shell properties of the interactions…
Self-consistent theory of large amplitude collective motion: Applications to approximate quantization of non-separable systems and to nuclear physics
G. Do Dang, A. Klein, N. R. Walet
The goal of the present account is to review our efforts to obtain and apply a ``collective'' Hamiltonian for a few, approximately decoupled, adiabatic degrees of freedom, starting…
Relativistic Faddeev approach to the NJL model at finite density
M. C. Birse, J. A. McGovern, S. Pepin +1
We study the nucleon solution of the relativistic Faddeev equation as a function of density in the framework of a generalized Nambu-Jona-Lasinio model. We truncate the interacting…
Local harmonic approaches with approximate cranking operators
takashi Nakatsukasa, Niels R. Walet, Giu Do Dang
Methods of large amplitude collective motion in the adiabatic limit are examined with a special emphasis on conservation laws. We show that the restriction to point transformations…
A basis of cranking operators for the pairing-plus-quadrupole model
Takashi Nakatsukasa, Niels R. Walet, Giu Do Dang
We investigate the RPA normal-mode coordinates in the pairing-plus-quadrupole model, with an eye on simplifying the application of large amplitude collective motion techniques. At…
Translationally invariant treatment of pair correlations in nuclei: II. Tensor correlations
R. F. Bishop, R. Guardiola, I. Moliner +4
We study the extension of our translationally invariant treatment of few-body nuclear systems to include tensor forces and correlations. It is shown that a direct application of ou…
Collective coordinates, shape transitions and shape coexistence: a microscopic approach
Takashi Nakatsukasa, Niels R. Walet
We investigate a description of shape-mixing and shape-transitions using collective coordinates. To that end we apply a theory of adiabatic large-amplitude motion to a simplified n…
Self-consistent collective subspaces and diabatic/adiabatic motion in nuclei
Takashi Nakatsukasa, Niels R Walet
We discuss the application of a theory of large-amplitude collective motion to a simple model mimicking the pairing-plus-quadrupole model of nuclear physics.
Diabatic and Adiabatic Collective Motion in a Model Pairing System
Takashi Nakatsukasa, Niels R. Walet
Large amplitude collective motion is investigated for a model pairing Hamiltonian containing an avoided level crossing. A classical theory of collective motion for the adiabatic li…
Large Amplitude Collective Motion in Nuclei and Metallic Clusters: Applicability of adiabatic theory for a pairing model
Takashi Nakatsukasa, Niels R. Walet
A model Hamiltonian describing a two-level system with a crossing plus a pairing force is investigated using technique of large-amplitude collective motion. The collective path, wh…
Translationally invariant treatment of pair correlations in nuclei: I. Spin and isospin dependent correlations
R. Guardiola, P. I. Moliner, J. Navarro +3
We study the extension of our translationally invariant treatment of few-body nuclear systems to heavier nuclei. At the same time we also introduce state-dependent correlation oper…
Application of a semi-microscopic core-particle coupling method to the backbending in odd deformed nuclei
Pavlos Protopapas, Abraham Klein, Niels R. Walet
In two previous papers, the Kerman-Klein-Donau-Frauendorf (KKDF) model was used to study rotational bands of odd deformed nuclei. Here we describe backbending for odd nuclei using…
Further application of a semi-microscopic core-particle coupling method to the properties of Gd155,157, and Dy159
Pavlos Protopapas, Abraham Klein, Niels R. Walet
In a previous paper a semi-microscopic core-particle coupling method that includes the conventional strong coupling core-particle model as a limiting case, was applied to spectra a…
Nuclear Transparency in Quasifree Electron Scattering - Theory and Experiment
Sherman Frankel, William Frati, Niels R. Walet
We make detailed comparisons between the measured dependency of nuclear transparency in quasifree electron scattering and theoretical predictions based on Glauber theory. We…