$R(D^{(*)})$ from $W'$ and right-handed neutrinos

TL;DR

This paper proposes a UV-complete model explaining the $R(D^{(*)})$ anomalies through a TeV-scale $W'$ boson and right-handed neutrinos, with broad phenomenological implications across flavor physics, collider searches, and cosmology.

Contribution

It introduces a novel extension of the Standard Model with an $SU(2)_V imes U(1)'$ gauge group and vector-like fermions, providing a comprehensive framework for $R(D^{(*)})$ anomalies and related phenomenology.

Findings

Model can fit $R(D^{(*)})$ data within experimental constraints

Predicts observable signals in dark radiation and collider displaced decays

Compatible with flavor physics, collider, and cosmological data

Abstract

We provide an ultraviolet (UV) complete model for the $R(D^{(*)})$ anomalies, in which the additional contribution to semi-tauonic $b \to c$ transitions arises from decay to a right-handed sterile neutrino via exchange of a TeV-scale $SU(2)_L$ singlet $W'$. The model is based on an extension of the Standard Model (SM) hypercharge group, $U(1)_Y$, to the $SU(2)_V\times U(1)'$ gauge group, containing several pairs of heavy vector-like fermions. We present a comprehensive phenomenological survey of the model, ranging from the low-energy flavor physics, direct searches at the LHC, to neutrino physics and cosmology. We show that, while the $W'$ and $Z'$-induced constraints are important, it is possible to find parameter space naturally consistent with all the available data. The sterile neutrino sector also offers rich phenomenology, including possibilities for measurable dark radiation, gamma ray signals, and displaced decays at colliders.