%0 Journal Article
%T Causality bounds for neutron-proton scattering
%A Serdar Elhatisari
%A Dean Lee
%J Physics
%D 2012
%I arXiv
%R 10.1140/epja/i2012-12110-x
%X We consider the constraints of causality and unitarity for the low-energy interactions of protons and neutrons. We derive a general theorem that non-vanishing partial-wave mixing cannot be reproduced with zero-range interactions without violating causality or unitarity. We define and calculate interaction length scales which we call the causal range and the Cauchy-Schwarz range for all spin channels up to J = 3. For some channels we find that these length scales are as large as 5 fm. We investigate the origin of these large lengths and discuss their significance for the choice of momentum cutoff scales in effective field theory and universality in many-body Fermi systems.
%U http://arxiv.org/abs/1206.1207v2