Fine-tuning problem in minimal SO(10) supersymmetric grand unified theories
- Max-Planck-Institut fuer Physik, Werner-Heisenberg-Institut, P.O. Box 40 12 12, Muenchen (Germany)
In grand unified theories (GUT`s) based on SO(10) all fermions of one generation are embedded in a single representation. As a result, the top quark, the bottom quark, and the {tau} lepton have a universal Yukawa coupling at the GUT scale. This implies a very large ratio of Higgs vacuum expectation values, tan{beta}{congruent}{ital m}{sub {ital t}}/{ital m}{sub {ital b}}. We analyze the naturalness of such a scenario quantitatively including all the relevant radiative corrections and find that, in minimal unified supergravity models with universal soft supersymmetry-breaking parameters at the GUT scale, the necessary amount of fine-tuning is excessive. The GUT threshold correction to the universal Higgs boson mass parameter can significantly reduce the fine-tuning required for such large values of tan{beta}. We also point out that the top quark mass can play a crucial role in explaining the hierarchy between the SUSY-breaking scale and the electroweak scale and, hence, the naturalness of large values of tan{beta}.
- OSTI ID:
- 249542
- Journal Information:
- Physical Review, D, Journal Name: Physical Review, D Journal Issue: 7 Vol. 52; ISSN 0556-2821; ISSN PRVDAQ
- Country of Publication:
- United States
- Language:
- English
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