Right-handed neutrinos and the CDF II anomaly

Abstract

We point out that right-handed neutrinos can resolve the tension between the latest CDF II measurement of ${M}_{W}$ and the SM. Integrating out the new states yields a single $d=6$ operator, which translates into a nonunitary leptonic mixing matrix. This alters the extraction of ${G}_{F}$ from muon decay and increases the prediction for ${M}_{W}$, in line with the CDF II result. We find that this explanation worsens the so-called Cabibbo anomaly, which could still be explained through the same $d=6$ operator if it is not generated by right-handed neutrinos. Exploiting the flavor dependence, a common explanation of both anomalies would a priori be possible, but is ruled out by weak universality constraints.