A PECULIAR PROPERTY OF SUSY AMPLITUDES AT HIGH ENERGY

We observe that the electroweak one-loop correction to the quark+gluon to quark+Higgs amplitude at high energy involves both single and quadratic logarithms of the energy in the SM case but only quadratic logarithms in the MSSM case. We explore the origin of this special SUSY cancellation, both in a diagrammatic way and through the splitting+parameter-renormalization procedure. We show that it is not an accident but a remarkable and general SUSY property of the renormalized Higgs–fermion–fermion and Higgsino–sfermion–fermion vertices which directly reflects in such processes, for example in bg→tH-, bg→bH0, bg→bh0, bg→bA0, and through equivalence in $bg\to tW^-_{\rm long}$, bg→bZlong, as well as in $bg\to \tilde{t}\chi^-$, $bg\to\tilde{b}\chi^0$. This simplification of the high energy behavior (which only leaves quadratic logarithms involving pure gauge couplings without any free parameter) allows to write simple relations among these various processes which could constitute genuine tests of the assumed SU...