The low energy effective theory and nucleon stability
Abstract
We show that the Standard Model Lagrangian, including small neutrino masses, has an anomalyfree discrete Z_6 symmetry. Anomaly cancellation requires the number of family to be 3 mod 6. This symmetry can ensure the stability of the nucleon even when the threshold of new physics \Lambda is low as 10^2 GeV. All \Delta B=1 and \Delta B=2 (B is the baryon number) effective operators are forbidden by the Z_6 symmetry. \Delta B=3 operators are allowed, but they arise only at dimension 15. We suggest a simple mechanism for realizing reasonable neutrino masses and mixings even with such a low scale for \Lambda.
 Publication:

arXiv eprints
 Pub Date:
 February 2004
 arXiv:
 arXiv:hepph/0402087
 Bibcode:
 2004hep.ph....2087G
 Keywords:

 High Energy Physics  Phenomenology
 EPrint:
 To appear in the Proceedings of SUSY 2003, held at the University of Arizona, Tucson, AZ, 510 June 2003