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James D. Wells

Publications and source records attributed to James D. Wells.

165 records · Page 10Linked to original sources

Annihilation Cross Sections for Relic Densities in the Low Velocity Limit

A simple method to calculate the total annihilation cross section of massive cold relics is presented. Exact expressions for $\arel$, $\brel$, and $\crel$ of $σ\vrel=\arel+\brel \vrel^2+\crel \vrel^4$ are obtained from simple derivatives of the squared annihilation amplitude. Three examples are given. In one example, the computed annihilation cross section of massive Dirac neutrinos confirms recent correct calculations.

hep-ph↗

Study of Constrained Minimal Supersymmetry

Taking seriously phenomenological indications for supersymmetry, we have made a detailed study of unified minimal SUSY, including effects at the few percent level in a consistent fashion. We report here a general analysis without choosing a particular unification gauge group. We find that the encouraging SUSY unification results of recent years do survive the challenge of a more complete and accurate analysis. Taking into account effects at the 5-10% level leads to several improvements of previous results, and allows us to sharpen our predictions for SUSY in the light of unification. We perform a thorough study of the parameter space. The results form a well-defined basis for comparing the physics potential of different facilities. Very little of the acceptable parameter space has been excluded by LEP or FNAL so far, but a significant fraction can be covered when these accelerators are upgraded. A number of initial applications to the understanding of the SUSY spectrum, detectability of SUSY at LEP II or FNAL, BR($b\to sγ$), Width($Z\to b\bar b$), dark matter, etc, are included in a separate section. We formulate an approach to extracting SUSY parameters from data when superpartners are detected. For small tan(beta) or large $m_top$ both $M_half$ and $M_0$ are entirely bounded from above at O(1 tev) without having to use a fine-tuning constraint.

hep-ph↗

Calculable Upper Limit on the Mass of the Lightest Higgs Boson in Any Perturbatively Valid Supersymmetric Theory

We show that there is a calculable upper limit on the mass of the lightest Higgs boson in any supersymmetric theory that remains perturbative up to a high scale . There are no restrictions on the Higgs sector, or the gauge group or particle content. We estimate the value of the upper limit to be $m_{\hcirc} < 146$ GeV for 100 GeV < $M_t$ < 145 GeV, from all effects except possibly additional heavy fermions beyond top (which could increase the limit by 0-20 GeV if any existed); for $M_t$ > 145 GeV the limit decreases monotonically. We expect to be able to decrease the value of the upper limit by at least a few percent by very careful analysis of the conditions. It is not normal in models for the actual mass to saturate the upper limit.

hep-ph↗