Search for three-nucleon force effects on the longitudinal response function of 4He

TL;DR

This study investigates the impact of three-nucleon forces on the longitudinal response function of helium-4 using ab initio calculations, highlighting the importance of these forces at low momentum transfers and their model dependence.

Contribution

It provides a detailed ab initio analysis of three-nucleon force effects on 4He response functions, considering full four-body continuum dynamics and multiple force models.

Findings

Three-nucleon forces significantly affect R_L at low q

Response function shows up to 10% dependence on force model

Low-q measurements can discriminate between force models

Abstract

A detailed study of the 4He longitudinal response function R_L(\omega,q) is performed at different kinematics, with particular emphasis on the role of three-nucleon forces. The effects shown are the results of an ab initio calculation where the full four-body continuum dynamics is considered via the Lorentz integral transform method. The contributions of the various multipoles to the longitudinal response function are analyzed and integral properties of the response are discussed in addition. The Argonne V18 nucleon-nucleon interaction and two different three-nucleon force models (Urbana IX, Tucson-Melbourne') are used. At lower momentum transfer (q<= 200$ MeV/c) three-nucleon forces play an important role. One even finds a dependence of R_L on the three-nucleon force model itself with differences up to 10%. Thus a Rosenbluth separation of the inclusive electron scattering cross section of 4He at low momentum transfer would be of high value in view of a discrimination between different three-nucleon force models.