Precision corrections to supersymmetric unification

Abstract

We compute the full set of weak-scale gauge and Yukawa threshold corrections in the minimal supersymmetric standard model, including all finite (non-logarithmic) corrections, which we show to be important. We use our results to examine the effects of unification-scale threshold corrections in the minimal and missing-doublet SU(5) models. We work in the context of a unified mass spectrum, with scalar mass M 0 and gaugino mass M 1/2 , and find that in minimal SU(5) with squark masses less than one TeV, successful gauge and Yukawa coupling unification requires M 1/2 ≪ M 0 and M 0 ≃ 1 TeV. In contrast, we find that the missing-doublet model permits gauge and Yukawa unification for a wide range of supersymmetric masses.

Effective couplings and perturbative unification

“…Therefore, if one wants to make use of the experimental data on the couplings, it is necessary to include the corrections due to the new degrees of freedom 10 . This is also the main issue of some recent work [13]. In these papers, a calculation of complete susy contributions is carried out in order to determine the value of sin 2 θ W (m Z ) | M S from experimental quantities, but in the context of the MSSM.…”

“…One way to avoid this result would be to considere a different unification group, which gives the reverse sign for this contribution [13]. We would have to look for a cancellation between "light" and "heavy" threshold effects.…”

“…In Section 5 we offer our conclusions, and discuss other approaches that have emerged in the recent literature [11][12][13]. The works cited on Ref.…”

“…The works cited on Ref. [13] remark the importance of complete light (susy) threshold effects for the determination of the MS values of the gauge couplings at the electroweak scale, as they are extracted from experimental quantities, and the later implication of these initial values for unification. Susy thresholds distinguish between the quantities extracted using the SM, from the same quantities obtained on the MSSM.…”

Disrupting the one-loop renormalization group invariant M/α in supersymmetry

“…The motivation for this is that one can always match a weak scale theory including full threshold corrections to the initial conditions we gave in the examples above. In practice, this matching can become rather complicated [34,35,36] if one demands a high level of precision. However, it is important to understand the origin of the uncertainties associated with weak scale thresholds, as well as recognizing that, for example, measured (pole) masses must be translated into renormalized masses, and the corrections can be large (especially for the gluino [20,34,36]).…”