A Measurement of the Branching Fraction ${\cal B} τ^+ \to h^- π^0 ν_τ$

Abstract

Using data from the CLEO II detector at CESR, we measure ${\cal B}(τ^\pm\rightarrow h^\pmπ^0ν_τ)$ where $h^\pm$ refers to either $π^\pm$ or $K^\pm$. We use three different methods to measure this branching fraction. The combined result is ${\cal B}(τ^\pm\rightarrow h^\pmπ^0ν_τ) = 0.2587 \pm 0.0012 \pm 0.0042$, in good agreement with Standard Model predictions. This result, in combination with other precision measurements, reduces the significance of the one-prong problem in tau decays. A postscript version is available through World-Wide-Web in http://w4.lns.cornell.edu/public/CLNS/1994/