Eur. Phys. J. A (2017) 53: 126
https://doi.org/10.1140/epja/i2017-12313-7

Regular Article - Theoretical Physics

Dipole-dipole dispersion interactions between neutrons

¹ ITAMP, Harvard-Smithsonian Center for Astrophysics, MS 14, 60 Garden St., 02138, Cambridge, MA, USA
² Instituto de Física, Universidade de São Paulo, R. do Matão 1371, 05508-090, São Paulo, S.P., Brazil
³ Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970, São Paulo, S.P., Brazil
⁴ Departamento de Física, Instituto Tecnológico de Aeronáutica, CTA, São José dos Campos, S.P., Brazil

^* e-mail: hussein@if.usp.br

Received: 19 December 2016
Accepted: 8 May 2017
Published online: 15 June 2017

Abstract

We investigate the long-range interactions between two neutrons utilizing recent data on the neutron static and dynamic electric and magnetic dipole polarizabilities. The resulting long-range potentials are used to make quantitative comparisons between the collisions of a neutron with a neutron and a neutron with a proton. We also assess the importance of the first pion production threshold and first excited state of the nucleon, the -resonance (, I = 3/2). We found both dynamical effects to be quite relevant for distances r between fm up to fm in the nn system, the neutron-wall system and in the wall-neutron-wall system, reaching the expected asymptotic limit beyond that. Relevance of our findings to the confinement of ultra cold neutrons inside bottles is discussed.