Standard Model Anomalies in Curved Space-Time with Torsion

Abstract

Using the Fujikawa and the heat-kernel methods we make a complete and detailed computation of the global, gauge and gravitational anomalies present in the Standard Model defined on a curved space time with torsion. We find new contributions coming from curvature and torsion terms to the leptonic number anomaly (so that $B-L$ is not conserved any more), to the $U(1)_Y$ gauge and to the mixed $U(1)_Y$-gravitational anomalies, but the gauge anomaly cancellation conditions on the hypercharges remain the same. We also find that the condition, usually related to the cancellation of the mixed $U(1)_Y$-gravitational anomaly, can be reobtained in the context of the Standard Model in flat space-time by requiring the cancellation of the global Lorentz anomaly without any reference to gravitation.