We study the structure of the soft SUSY-breaking terms obtained from 4-D Strings under the assumption of dilaton/moduli dominance in the process of SUSY-breaking. We first analyze in detail the dilaton-dominated limit because of its finiteness properties and phenomenological predictivity, and second, we consider the new features appearing when several moduli fields contribute to SUSY breaking. In particular, we discuss in detail the case of symmetric Abelian orbifolds. Although some qualitative features indeed change in the multimoduli case with respect to the dilaton dominance one, the most natural mass relations at low-energy, m l < m q ⋍ M g, are still similar. Only in some very specific limits these relations might be reversed. We also study the presence of tachyons pointing out that their possible existence may be, in some cases, an interesting advantage in order to break extra gauge symmetries. Finally, we compute explicitly the μ and B parameters in the context of the mechanism for generating a " μ-term" by the Kähler potential, as naturally implemented in orbifolds. It leads to the prediction | tgβ| = 1 at the String scale, independently of the Goldstino direction. It is worth noticing that, in this squeme, the dilaton-dominated case, where there is no free parameters, is excluded since it is not consistent with the measured value of the top-quark mass. In this connection, low-energy charge and color breaking minima are also discussed.
Nuclear Physics B Proceedings Supplements
- Pub Date:
- June 1996
- High Energy Physics - Phenomenology;
- High Energy Physics - Theory
- 11 pages, Latex with hep93.sty included, uuencoded, Based on talks given at the 29th International Symposium on the Theory of Elementary Particles, Buckow (Berlin), August 1995