Nir Polonsky

Uncertainties in coupling constant unification

The status of coupling constant unification in the standard model and its supersymmetric extension are discussed. Uncertainties associated with the input coupling constants,

Nonuniversal GUT corrections to the soft terms and their implications in supergravity models

{\mathit{m}}_{\mathit{t}}

Strong coupling, unification, and recent data

, threshold corrections at the low and high scales, and possible nonrenormalizable operators are parametrized and estimated. A simple parametrization of a general supersymmetric new particle spectrum is given. It is shown that an effective scale

Grand-unification effects in the soft supersymmetry breaking terms

{\mathit{M}}_{\mathrm{SUSY}}

Bottom quark mass prediction in supersymmetric grand unification: Uncertainties and constraints.

can be defined, but for a realistic spectrum it may differ considerably from the typical new particle masses. The implications of the lower (higher) values of

Implications of Yukawa unification for the Higgs sector in supersymmetric grand unified models

{\mathrm{\ensuremath{\alpha}}}_{\mathit{s}}

Higgs- and Slepton-Strahlung at Hadron Colliders

(

Fermion Masses without Yukawa Couplings

{\mathit{M}}_{\mathit{Z}}

Unification and low-energy supersymmetry at one and two-loop orders

) suggested by low-energy (Z-pole) experiments are discussed.

An Upper bound on the Higgs boson mass from Yukawa unification and a comment on vacuum stability constraints

Potentially large nonuniversal corrections to the soft supersymmetry-breaking parameters arise from their evolution between the Planck and the grand-unification scales. We detail typical patterns of nonuniversality in GUT models, as well as elaborate on their propagation to the weak scale and on their low-energy implications. Possible corrections to the different scalar quark and lepton masses and the Higgs and the gaugino-Higgsino sector parameters are described in detail, and new allowed regions of the parameter space are pointed out. In particular, the patterns studied often lead to heavier Higgsinos and {ital t} scalars. One-loop GUT threshold corrections to the soft parameters are also discussed and shown to be important.