Search for a Very Light CP-Odd Higgs Boson in Top Quark Decays from p-anti-p Collisions at 1.96 TeV

TL;DR

This paper searches for a very light CP-odd Higgs boson in top quark decays using proton-antiproton collision data, setting limits on decay probabilities due to no significant signal observed.

Contribution

It introduces a search for a light CP-odd Higgs in top decays and provides the first experimental limits on its branching ratio in this context.

Findings

No significant excess over background observed.

95% confidence level limits set on t -> H^+ b branching ratio.

Constraints vary with different H^+ and a_1^0 masses.

Abstract

We present the results of a search for a very light CP-odd Higgs boson $a_1^0$ originating from top quark decays t -> H^+ b -> W^+ a_1^0 b, and subsequently decaying into tau-tau. Using a data sample corresponding to an integrated luminosity of 2.7 inv fb collected by the CDF II detector in p-anti-p collisions at 1.96 TeV, we perform a search for events containing a lepton, three or more jets, and an additional isolated track with transverse momentum in the range 3 to 20 GeV/c. Observed events are consistent with background sources, and 95% C.L. limits are set on the branching ratio of t -> H^+ b for various masses of H^+ and a_1^0.