Radiative Capture of Cold Neutrons by Protons and Deuteron Photodisintegration with Twisted Beams

Abstract

We consider two basic nuclear reactions: Radiative capture of neutrons by protons, $n+p\to \gamma+~d$ and its time-reversed counterpart, photodisintegration of the deuteron, $\gamma +d\to n+p$. In both of these cases we assume that the incoming beam of neutrons or photons is "twisted" by having an azimuthal phase dependence, {\it i.e.}, it carries an additional angular momentum along its direction of propagation. Taking a low-energy limit of these reactions, we derive relations between corresponding transition amplitudes and cross sections with plane-wave beams and twisted beams. Implications for experiments with twisted cold neutrons and photon beams are discussed.