Supersymmetric grand unified theories: Two-loop evolution of gauge and Yukawa couplings
Abstract
We make a numerical study of guage and Yukawa unification in supersymmetric grand unified models and examine the quantitative implications of fermion mass Ansa$iuml-tze at the grand unified scale. Integrating the renormalization group equations with α1(MZ) and α2(MZ) as inputs, we find α3(MZ)~=0.111(0.122) for MSUSY=mt and α3(MZ)~=0.106(0.116) for MSUSY=1 TeV at one-loop (two-loop) order. Including b and τ Yukawa couplings in the evolution, we find an upper limit of mt<~200 GeV from Yukawa unification. For given mt<~175 GeV, there are two solutions for β: one with tanβ>mt/mb, and one with sinβ~=0.78(mt/150 GeV). Taking a popular Ansatz for the mass matrices at the unified scale, we obtain a lower limit on the top-quark mass of mt>~150(115) GeV for α3(MZ)=0.11(0.12) and an upper limit on the supersymmetry parameter tanβ<~50 if α3(MZ)=0.11. The evolution of the quark mixing elements is also evaluated.
- Publication:
-
Physical Review D
- Pub Date:
- February 1993
- DOI:
- 10.1103/PhysRevD.47.1093
- arXiv:
- arXiv:hep-ph/9209232
- Bibcode:
- 1993PhRvD..47.1093B
- Keywords:
-
- 12.10.Dm;
- 12.15.Ff;
- Unified theories and models of strong and electroweak interactions;
- Quark and lepton masses and mixing;
- High Energy Physics - Phenomenology
- E-Print:
- 46 pages + 11 figures not included (available on request), MAD/PH/711