Computing the Weak Mixing Angle from Anomaly Cancellation

L. E. Ibáñez

doi:10.1016/0370-2693(93)90043-H

paper

Computing the Weak Mixing Angle from Anomaly Cancellation

arXiv:hep-ph/9205234 · doi:10.1016/0370-2693(93)90043-H

Abstract

I remark that the weak mixing angle in the standard model may be computed even in the absence of a grand unification symmetry. In particular, if there is an additional gauged $U (1)$ symmetry at some large scale which can be made anomaly-free only by a Green-Schwarz (GS) mechanism, this typically results in a prediction for the weak angle. In the case of the standard model one can see that the standard Peccei-Quinn symmetry may be gauged and the anomalies cancelled through a GS mechanism. Remarkably enough, cancelation of anomalies works only for the `canonical' value $s i n^{2} θ_{W} = 3/8$ . In the case of the supersymmetric standard model one can also find $U (1)$ currents which may be made anomaly-free through a GS but the canonical value is only obtained in the absence of any Higgs multiplet. If the analysis is extended to include $U (1)$ R-symmetries, there is a unique class of $U (1)$ s which give rise to the canonical value. The R-symmetry is only anomaly-free for $s i n^{2} θ_{W} = (4 N_{g} - 3) / (10 N_{g} - 3 N_{D} - 3)$ , where $N_{g}, N_{D}$ are the number of generations and Higgs pairs. The natural context in which the above scenario may naturally arise is string theory. I also emphasize other interesting possibilities offered by the GS mechanism to model-building.

17.p

Computing the Weak Mixing Angle from Anomaly Cancellation

Abstract

Cited by in corpus (81)