Right-handed neutrinos and the CDF II anomaly

We point out that right-handed neutrinos can resolve the tension between the latest CDF II measurement of MW and the SM. Integrating out the new states yields a single d 1/4 6 operator, which translates into a nonunitary leptonic mixing matrix. This alters the extraction of GF from muon decay and increases the prediction for MW, 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 1/4 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.

Automated summary

Right-handed neutrinos can resolve the tension between the latest CDF II measurement of MW and the standard model (SM). The explanation alters the extraction of GF from muon decay and increases the prediction for MW, in line with the CDF II result. However, it worsens the Cabibbo anomaly unless it is not generated by right-handed neutrinos.