The nn quasi-free nd breakup cross section: discrepancies to theory and implications on the 1S0 nn force

Abstract

Large discrepancies between quasi-free neutron-neutron (nn) cross section data from neutron-deuteron (nd) breakup and theoretical predictions based on standard nucleon-nucleon (NN) and three-nucleon (3N) forces are pointed out. The nn 1S0 interaction is shown to be dominant in that configuration and has to be increase to bring theory and data into agreement. Using the next-to-leading order (NLO) 1S0 interaction of chiral perturbation theory (chiPT) we demonstrate that the nn QFS cross section only slightly depends on changes of the nn scattering length but is very sensitive to variations of the effective range parameter. In order to account for the reported discrepancies one must decrease the nn effective range parameter by about 12 % from its value implied by 19charge symmetry and charge independence of nuclear forces.

arXiv comment19 pages, 11 figures

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Cited by in corpus (9)

• Few- and many-nucleon systems with semilocal coordinate-space regularized chiral nucleon-nucleon forces
• Low-energy neutron-deuteron reactions with N3LO chiral forces
• Calculations of three-nucleon reactions with N3LO chiral forces: achievements and challenges
• Dineutron and the three-nucleon continuum observables
• Determination of energy of nn-singlet virtual state in d+2H->p+p+n+n reaction
• Search for a bound di-neutron by comparing ${}^3$He(e,e'p)d and ${}^3$H(e,e'p)X measurements
• Measurement of the ${}^1{S}_0$ neutron-neutron effective range in neutron-deuteron breakup
• Neutron-neutron quasifree scattering in neutron-deuteron breakup at 10 MeV
• Study of n-n correlations in d + 2H --> p + p + n + n reaction