https://doi.org/10.1140/epjs/s11734-021-00291-x
Regular Article
Multinucleon excitations in neutrino–nucleus scattering: connecting different microscopic models for the correlations
1
Univ Lyon, Univ Claude Bernard Lyon 1, CNRS/IN2P3, IP2I Lyon, UMR 5822, 69622, Villeurbanne, France
2
Theory Department, CERN, 12111, Geneva, Switzerland
3
IPSA-DRII, 63 boulevard de Brandebourg, 94200, Ivry-sur-Seine, France
4
Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), Sorbonne Université, Université Paris Diderot, CNRS/IN2P3, Paris, France
Received:
30
June
2021
Accepted:
19
September
2021
Published online:
1
November
2021
The problem of nucleon–nucleon correlations and meson exchange currents has been vividly debated in connection with the neutrino–nucleus cross sections. In this work we focus on nucleon–nucleon correlations by discussing a formal correspondence between the approaches based on independent particles and the ab initio approaches involving correlated wave functions. We use a general technique based on unitary transformation mapping the Fermion operators relative to bare nucleons into quasi-particle operators relative to dressed nucleons. We derive formulas for spectral functions, response functions, momentum distribution, separation energy, general enough to be applied with any kind of effective nucleon–nucleon interaction. We establish the relation between the non-energy-weighted sum rule and the Fermi sea depopulation. With our tools we evaluate whether approaches based on effective interactions are compatible with the expected amount of correlations coming from ab initio calculations. For this purpose we use as a test the Fermi sea depopulation and the value of the kinetic energy per nucleon.
© The Author(s), under exclusive licence to EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature 2021
