The ${\nu }_R$-philic scalar: its loop-induced interactions and Yukawa forces in LIGO observations

Abstract

Right-handed neutrinos (${\nu }_R$) are often considered as a portal to new hidden physics. It is tempting to consider a gauge singlet scalar $(\varphi )$ that exclusively couples to ${\nu }_R$ via a ${\nu }_R{\nu }_R\varphi$ term. Such a ${\nu }_R$-philic scalar does not interact with charged fermions at tree level but loop-induced effective interactions are inevitable, which are systematically investigated in this work. The magnitude of the loop-induced couplings coincidentally meets the current sensitivity of fifth-force searches. In particular, the loop-induced coupling to muons could be tested in the recent LIGO observations of neutron star mergers as there might be a sizable Yukawa force in the binary system mediated by the ${\nu }_R$-philic scalar.

Comments: 24 pages, 5 figures, results of the pseudo-scalar case added, JHEP published version. Code available from https://github. com/xunjiexu/vR_loop