Measurements of Branching Fractions of $\tau$ Lepton Decays with one or more $\it{K^{0}_{S}}$

Physical review / D 89, 072009 (2014). doi:10.1103/PhysRevD.89.072009
We report measurements of branching fractions of $\tau $ lepton decays to final states with a ${K}_{S}^{0}$ meson using a $669\text{}\text{}{\mathrm{fb}}^{-1}$ data sample accumulated with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{-}$ collider. The inclusive branching fraction is measured to be $\mathcal{B}\left({\tau }^{-}\to {K}_{S}^{0}{X}^{-}{\nu }_{\tau }\right)=\left(9.15±0.01±0.15\right)×1{0}^{-3}$, where ${X}^{-}$ can be anything; the exclusive branching fractions are $\mathcal{B}\left({\tau }^{-}\to {\pi }^{-}{K}_{S}^{0}{\nu }_{\tau }\right)=\left(4.16±0.01±0.08\right)×\phantom{\rule{0ex}{0ex}}1{0}^{-3}$, $\mathcal{B}\left({\tau }^{-}\to {K}^{-}{K}_{S}^{0}{\nu }_{\tau }\right)=\left(7.40±0.07±0.27\right)×1{0}^{-4}$, $\mathcal{B}\left({\tau }^{-}\to {\pi }^{-}{K}_{S}^{0}{\pi }^{0}{\nu }_{\tau }\right)=\left(1.93±0.02±0.07\right)×1{0}^{-3}$, $\mathcal{B}\left({\tau }^{-}\to {K}^{-}{K}_{S}^{0}{\pi }^{0}{\nu }_{\tau }\right)=\left(7.48±0.10±0.37\right)×1{0}^{-4}$, $\mathcal{B}\left({\tau }^{-}\to {\pi }^{-}{K}_{S}^{0}{K}_{S}^{0}{\nu }_{\tau }\right)=\left(2.33±0.03±0.09\right)×1{0}^{-4}$, $\mathcal{B}\left({\tau }^{-}\to {\pi }^{-}{K}_{S}^{0}{K}_{S}^{0}{\pi }^{0}{\nu }_{\tau }\right)=\left(2.00±0.22±0.20\right)×1{0}^{-5}$, where the first uncertainty is statistical and the second is systematic. For each mode, the accuracy is improved over that of pre-$B$-factory measurements by a factor ranging from five to ten. In ${\tau }^{-}\to {\pi }^{-}{K}_{S}^{0}{K}_{S}^{0}{\pi }^{0}{\nu }_{\tau }$ decays, clear signals for the intermediate states ${\tau }^{-}\to {\pi }^{-}{f}_{1}\left(1285\right){\nu }_{\tau }$ and ${\tau }^{-}\to {K}^{*-}{K}_{S}^{0}{\pi }^{0}{\nu }_{\tau }$ are observed.
Published by American Physical Society, [S.l.]