Charged kaon production in tau decays at LEP

Abstract

Kaon production in one prong tau decays has been studied using data collected with the DELPHI detector at the LEP collider. Charged kaons were identified over a large momentum range by the DELPHI barrel Ring Imaging Cherenkov detector. The following branching ratios have been determined: BR( τ→ Kν τ )=(0.85±0.18)%, BR( τ→ Kν τ ≥0 neutrals)=(1.54±0.24)%, BR( τ→ Kν τ ≥1 neutrals)=(0.69±0.25)%. The result for the exclusive branching ratio is consistent with the Standard Model prediction based on τ- μ- e universality. In addition, tau decay into K ∗− was studied in the channel K ∗−→K −π 0 . The result BR(τ→K ∗−ν τ)× BR(K ∗−→K −π 0)=(0.57±0.23)% was obtained.