Right-handed Neutrinos and $R(D^{(*)})$

Understand

We explore scenarios where the $R(D^{(*)})$ anomalies arise from semitauonic decays to a right-handed sterile neutrino.

• We perform an EFT study of all five simplified models capable of generating at tree-level the lowest dimension electroweak operators that give rise to this decay.
• We analyze their compatibility with current $R(D^{(*)})$ data and other relevant hadronic branching ratios, and show that one simplified model is excluded by this analysis.
• The remainder are compatible with collider constraints on the mediator semileptonic branching ratios, provided the mediator mass is of order TeV.