Soft terms from strings
Abstract
We study the structure of the soft SUSYbreaking terms obtained from 4D Strings under the assumption of dilaton/moduli dominance in the process of SUSYbreaking. We first analyze in detail the dilatondominated 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 lowenergy, 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 " μterm" 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 dilatondominated case, where there is no free parameters, is excluded since it is not consistent with the measured value of the topquark mass. In this connection, lowenergy charge and color breaking minima are also discussed.
 Publication:

Nuclear Physics B Proceedings Supplements
 Pub Date:
 June 1996
 DOI:
 10.1016/09205632(96)003222
 arXiv:
 arXiv:hepph/9601325
 Bibcode:
 1996NuPhS..49...96M
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Theory
 EPrint:
 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