1992/05/26 by Luis E. Ibáñez, L. E. Ibáñez · 7 citations
Physics and Astronomy · #Anomaly (physics) #Atomic and Subatomic Physics Research #Computer science #Condensed matter physics #Mixing (physics) #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #hep-ph
paper · pdf · doi:10.1016/0370-2693(93)90043-h
published as Phys.Lett. B303 (1993) 55-62 · 17.p
arxiv created 1992/05/26 · openalex publication_date 1993/04/01 · openalex created_date 2016/06/24 · arxiv updated 2016/09/01 · openalex updated_date 2026/08/05
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 sin2θW=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 sin2θW=(4Ng-3)/(10Ng-3ND-3), where Ng,ND 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.