Dineutron and the three-nucleon continuum observables

TL;DR

This paper explores the potential existence of a hypothetical dineutron bound state and its impact on neutron-deuteron reaction observables, using extended three-nucleon Faddeev equations to compare with experimental data.

Contribution

It introduces an extension of the momentum space Faddeev equations to include a dineutron bound state, analyzing its effects on reaction observables and constraining its possible existence.

Findings

Data cannot decisively exclude dineutron existence.

Dineutron significantly affects the final-state-interaction peak.

Positive neutron-neutron scattering length likely inconsistent with dineutron presence.

Abstract

We investigate how strong a hypothetical 1S0 bound state of two neutrons would affect different observables in the neutron-deuteron reactions. To that aim we extend our momentum space scheme of solving three-nucleon Faddeev equations to incorporate in addition to the deuteron also the 1S0 dineutron bound state. We discuss effects induced by dineutron on the angular distribution of the neutron-deuteron elastic scattering and cross sections of the deuteron breakup. A comparison to the available data for neutron-deuteron total cross sections and elastic scattering angular distributions cannot decisively exclude a possibility that the two neutrons can form 1S0 bound state. However, the strong modifications of a final-state-interaction peak of the neutron-deuteron breakup when changing from negative to positive values of the neutron-neutron scattering length seems to exclude existence of dineutron.