Search for Pair Production of Scalar Top Quarks Decaying to a tau Lepton and a b Quark in ppbar Collisions at sqrt{s}=1.96 TeV

TL;DR

This paper reports a search for scalar top quark pair production decaying to tau and b quarks in proton-antiproton collisions, setting mass limits and cross section constraints based on observed data.

Contribution

First search for scalar top quark pair production with R-parity violating decay to tau and b quarks at Tevatron energies, establishing new mass limits.

Findings

No excess over standard model background observed.

Set a 95% CL lower mass limit of 153 GeV/c^2 for the scalar top quark.

Constraints also apply to third generation scalar leptoquarks.

Abstract

We search for pair production of supersymmetric top quarks (~t_1), followed by R-parity violating decay ~t_1 -> tau b with a branching ratio beta, using 322 pb^-1 of ppbar collisions at sqrt{s}=1.96 TeV collected by the CDF II detector at Fermilab. Two candidate events pass our final selection criteria, consistent with the standard model expectation. We set upper limits on the cross section sigma(~t_1 ~tbar_1)*beta^2 as a function of the stop mass m(~t_1). Assuming beta=1, we set a 95% confidence level limit m(~t_1)>153 GeV/c^2. The limits are also applicable to the case of a third generation scalar leptoquark (LQ_3) decaying LQ_3 -> tau b.