CP violation and circular polarisation in neutrino radiative decay

• Published in: The journal of high energy physics Vol. 2020; no. 4
• Main Authors: Balaji, Shyam, Ramirez-Quezada, Maura, Zhou, Ye-Ling
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2020; Springer Nature B.V
• Subjects: Circular polarization; Classical and Quantum Gravitation; CP violation; Dark matter; Decay; Elementary Particles; Fermions; High energy physics; Matter & antimatter; Neutrinos; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Neutrino Physics; CP violation; Cosmology of Theories beyond the SM
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP04(2020)178

A bstract The radiative decay of neutral fermions has been studied for decades but CP violation induced within such a paradigm has evaded attention. CP violation in these processes can produce an asymmetry between circularly polarised directions of the radiated photons and produces an important source of net circular polarisation in particle and astroparticle physics observables. The results presented in this work outlines the general connection between CP violation and circular polarisation for both Dirac and Majorana fermions and can be used for any class of models that produce such radiative decays. The total CP violation is calculated based on a widely studied Yukawa interaction considered in both active and sterile neutrino radiative decay scenarios as well as searches for dark matter via direct detection and collider signatures. Finally, the phenomenological implications of the formalism on keV sterile neutrino decay, leptogenesis-induced right-handed neutrino radiative decay and IceCube-driven heavy dark matter decay are discussed.