Normal-ordering approximations and translational (non)invariance
Artikel i vetenskaplig tidskrift, 2021

Normal ordering provides an approach to approximate three-body forces as effective two-body operators and it is therefore an important tool in many-body calculations with realistic nuclear interactions. The corresponding neglect of certain three-body terms in the normal-ordered Hamiltonian is known to influence translational invariance, although the magnitude of this effect has not yet been systematically quantified. In this paper we study in particular the normal-ordering two-body approximation applied to a single harmonic-oscillator reference state. We explicate the breaking of translational invariance and demonstrate the magnitude of the approximation error as a function of model space parameters for He-4 and O-16 by performing full no-core shell-model calculations with and without three-nucleon forces. We combine two different diagnostics to better monitor the breaking of translational invariance. While the center-of-mass effect is shown to become potentially very large for He-4, it is also shown to be much smaller for O-16 although full convergence is not reached. These tools can be easily implemented in studies using other many-body frameworks and bases.


Tor Djärv

Chalmers, Fysik, Subatomär, högenergi- och plasmafysik

Andreas Ekström

Chalmers, Fysik, Subatomär, högenergi- och plasmafysik

Christian Forssén

Chalmers, Fysik, Subatomär, högenergi- och plasmafysik

G. R. Jansen

Oak Ridge National Laboratory

Physical Review C

24699985 (ISSN) 24699993 (eISSN)

Vol. 104 2 024324

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Europeiska kommissionen (EU) (EC/H2020/758027), 2018-02-01 -- 2023-01-31.

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Språkteknologi (språkvetenskaplig databehandling)


Matematisk analys



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