# Modelling double charge exchange response function for tetraneutron system

## TL;DR

This paper models the response function of the tetraneutron system to analyze potential resonance phenomena, revealing that an unphysically large three-neutron force is needed to reproduce observed enhancements, which challenges standard nuclear models.

## Contribution

It introduces a response function model for the tetraneutron system and investigates the necessity of an unphysical three-neutron force to explain experimental enhancements.

## Key findings

- Resonance can only be reproduced with an unphysically large T=3/2 attractive 3n-force.
- No cusp or related structures were found in the response.
- Standard nuclear Hamiltonian cannot account for the observed enhancement.

## Abstract

This work is an attempt to model the $4n$ response function of a recent RIKEN experimental study of the double charge exchange $^4$He($^8$He,$^8$Be)$^4$n reaction in order to put in evidence an eventual enhancement mechanism of the zero energy cross section, including a near-threshold resonance. This resonance can indeed be reproduced only by adding to the standard nuclear Hamiltonian an unphysically large T=3/2 attractive 3n-force which destroys the neighboring nuclear chart. No other mechanisms like cusps or related structures were found.