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Monopole-induced baryon-number violation in ''realistic'' grand unified theories

Journal Article · · Phys. Rev. D; (United States)
We consider the embedding of the SU(2) monopole of 't Hooft and Polyakov into ''realistic'' grand unified theories (GUT's) and find a complication that may possibly interfere with the Callan-Rubakov effect. The fine tuning that keeps the weak-interaction scale much smaller than the GUT scale is necessarily upset in the vicinity of a magnetic monopole, and there is a probability of order one that the Weinberg-Salam Higgs field will have a GUT-scale expectation value at the monopole core. This means that the fermions could have a large effective mass at the core which could act as a barrier to exclude the fermions from the baryon-number-violating interactions inside the monopole core. In this paper we determine whether such a barrier is likely to cause a significant suppression of the Callan-Rubakov effect. Our analysis involves a variational determination of a position-dependent mass for the fermions in Callan's soliton formalism. Once the position-dependent mass of the solitons has been determined, simple energy arguments allow us to determine if the Callan-Rubakov effect will be suppressed. We find that in ordinary GUT's, the small Yukawa couplings between the Weinberg-Salam Higgs field and the light fermions keep the effective soliton masses very small so baryon-number violation is not affected, but if the Yukawa couplings are larger than 10/sup -3/ (instead of the usual 102)/sup 5/) or with the appropriate tuning of Higgs-field parameters, the soliton masses can become large at the core, and the Callan-Rubakov effect can be prevented. In the event that the Callan-Rubakov effect is suppressed, we find that baryon-number violation is still possible through the weak-anomaly-induced process discussed by Schellekens and Sen.
Research Organization:
Stanford Linear Accelerator Center and Physics Department, Stanford University, Stanford, California 94305
DOE Contract Number:
AC03-76SF00515
OSTI ID:
5602097
Journal Information:
Phys. Rev. D; (United States), Journal Name: Phys. Rev. D; (United States) Vol. 31:9; ISSN PRVDA
Country of Publication:
United States
Language:
English