arXiv subjects

P. W. Coulter

Publications and source records attributed to P. W. Coulter.

5 recordsLinked to original sources

arXiv1998

Virtual Supersymmetric Corrections in e^+e^- Annihilation

Depending on their masses, Supersymmetric particles can affect various measurements in Z decay. Among these are the total width (or consequent extracted value of $α_s$), enhancement or suppression of various flavors, and left-right and forward-backward asymmetries. The latter depend on squark mass splittings and are, therefore, a possible test of the Supergravity related predictions. We calculate leading order corrections for these quantities considering in particular the case of light photino and gluino where the SUSY effects are enhanced. In this limit the effect on $α_s$ is appreciable, the effect on $R_b$ is small, and the effect on the asymmetries is extremely small.

hep-ph↗

arXiv1996

Gluino Contribution to the 3-loop QCD beta function in the Minimal Supersymmetric Standard Model

We deduce the gluino contribution to the three-loop QCD βfunction within the minimal supersymmetric Standard Model (MSSM) from its standard QCD expression. The result is a first step in the computation of the full MSSM three-loop βfunction. In addition, in the case of a light gluino it provides the strong three-loop SUSY correction to the extrapolation of the strong coupling constant from the low energy regime to the Z region and up to the squark threshold.

hep-ph↗

arXiv1995

SUSY Unification with Smooth Threshold Behavior

Going beyond the theta function approximation we discuss supersymmetric unification of gauge couplings with exact decoupling of light and heavy particles at energy scales below their masses. We find that the Minimal SUSY model is strongly disfavored while the Missing Doublet Model survives with GUT scale masses rising into the $10^{18}$ GeV region.

hep-ph↗

arXiv1992

Squarks Below the Z

We investigate the possibility that the difference between the measurements of $α_3(M_Z)$ from the hadronic branching ratio of the $Z^0$ and the world average of other measurements is due to the decay of the $Z^0$ into quark, anti-squark, and gluino. Consequences for supersymmetry breaking models are discussed.

hep-ph↗

arXiv1992

Best Fit to the Gluino Mass

Assuming that perturbative QCD is the dominant explanation for the narrowness of the vector quarkonia, we perform a $χ^2$ minimization analysis of their hadronic decays as a function of two parameters, the mass of the gluino and the value of $α_3(M_Z)$. A value below 1 GeV for the gluino mass is strongly preferred. Consequences for SUSY breaking scenarios are discussed.

hep-ph↗