Enhanced Supersymmetric Corrections to Top-Quark Production at the Tevatron

We calculate the one-loop supersymmetric electroweak and QCD corrections to the top-quark pair-production cross section at the Tevatron, including the important effects of non-degenerate top-squarks and left-right top-squark mixing. The largest electroweak effects yield a negative shift in the cross section and are enhanced right below the threshold for top-quark decay into top-squark and higgsino-like neutralino, and can be as large as −35%. The largest QCD effects are positive and are enhanced for light top-squark masses, and can be as large as 20%. Such shifts greatly exceed the present theoretical uncertainty in the Standard Model prediction, and therefore may be experimentally observable. We also explore the one-loop shifts in scenarios containing light top-squarks and higgsino-like neutralinos, that have been recently proposed to explain various apparent experimental anomalies. ACT-05/96 DOE/ER/40717–26 CTP-TAMU-13/96 May 1996