Precision measurement of the $\mathcal{B}(\hat{I}\yen (3S)\to \ddot{I}{„}^{+}\ddot{I}{„}^{-})/\mathcal{B}(\hat{I}\yen (3S)\to \hat{I}{¼}^{+}\hat{I}{¼}^{-})$ ratio

Abstract

We report on a precision measurement of the ratio ${\mathcal{R}}_{\ddot{I}„\hat{I}¼}^{\hat{I}\yen (3S)}=\mathcal{B}(\hat{I}\yen (3S)\to \ddot{I}{„}^{+}\ddot{I}{„}^{-})/\mathcal{B}(\hat{I}\yen (3S)\to \hat{I}{¼}^{+}\hat{I}{¼}^{-})$ using data collected with the BaBar detector at the SLAC PEP-II $e^{+}{e}^{-}$ collider. The measurement is based on a 28 fb${}^{-1}$ data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million $\hat{I}\yen (3S)$ mesons. The ratio is measured to be ${\mathcal{R}}_{\ddot{I}„\hat{I}¼}^{\hat{I}\yen (3S)}=0.966\pm 0.008_{\mathrm{stat}}\pm 0.014_{\mathrm{syst}}$ and is in agreement with the Standard Model prediction of 0.9948 within 2 standard deviations. The uncertainty in ${\mathcal{R}}_{\ddot{I}„\hat{I}¼}^{\hat{I}\yen (3S)}$ is almost an order of magnitude smaller than the only previous measurement.

8 pages, 4 figures, 3 tables