https://doi.org/10.1140/epja/s10050-024-01480-7
Regular Article - Theoretical Physics
Ab initio Bogoliubov many-body perturbation theory: closed-form constraint on the average particle number
1
KU Leuven, Instituut voor Kern- en Stralingsfysica, 3001, Leuven, Belgium
2
IRFU, CEA, Université Paris-Saclay, 91191, Gif-sur-Yvette, France
3
Department of Physics, Technische Universität Darmstadt, 64289, Darmstadt, Germany
4
ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
5
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117, Heidelberg, Germany
Received:
24
July
2024
Accepted:
22
December
2024
Published online:
28
January
2025
Bogoliubov many-body perturbation theory (BMBPT) relying on the breaking of U(1) global gauge symmetry has been recently formulated and applied to extend the applicability of standard perturbation theory to ab initio calculations of atomic nuclei away from shell closures. So far, practical applications have been limited to second-order calculations due to the lack of a generic algorithm to constrain the average particle number of the symmetry-broken state. This limitation is presently lifted and a general BMBPT formalism is presented that allows to constrain the particle-number expectation value at arbitrary order P. The constraint can be incorporated in closed form by solving a polynomial equation of degree . The numerical procedure is illustrated through BMBPT(3) calculations of calcium isotopes using a nuclear Hamiltonian derived within chiral effective field theory.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.