Study of the Hadronic Transitions $\hat{I}\yen$(2S)$\to (\hat{I}\cdot ,\ddot{I}{€}^0)\hat{I}\yen$(1S) at Belle

Abstract

We study the rare hadronic transitions $\hat{I}\yen (2S)\to \hat{I}\yen (1S)\hat{I}\cdot$ and $\hat{I}\yen (2S)\to \hat{I}\yen (1S)\ddot{I}{€}^0$ using a sample of 158 $\times 10^6$ $\hat{I}\yen (2S)$ decays collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. We observe the $\hat{I}\cdot$ meson decay to ${\hat{I}}^3{\hat{I}}^3$ and $\ddot{I}{€}^{+}\ddot{I}{€}^{-}\ddot{I}{€}^0$ final states; the $\hat{I}\yen (1S)$ is reconstructed in the $\hat{I}{¼}^{+}\hat{I}{¼}^{-}$ and $e^{+}{e}^{-}$ decay modes. We measure the ratios of branching fractions ($\mathcal{B}$) $\frac{\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\hat{I}\cdot )}{\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\ddot{I}{€}^{+}\ddot{I}{€}^{-})}$ = (1.99$\pm$0.14 (stat) $\pm$0.11 (syst)) $\times 10^{-3}$ and $\frac{\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\ddot{I}{€}^0)}{\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\ddot{I}{€}^{+}\ddot{I}{€}^{-})}<2.3\times 10^{-4}$ at the 90% confidence level (CL). Assuming the value $\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\ddot{I}{€}^{-}\ddot{I}{€}^{+})$ = (17.92$\pm$0.26)%, we obtain $\mathcal{B}(\hat{I}\yen (2S)\to \hat{I}\yen (1S)\hat{I}\cdot )=(3.57\pm 0.25(\mathrm{stat})\pm 0.21(\mathrm{syst}))\times 10^{-4}$ and $ {\mathcal B}(Î¥(2S)\rightarrowÎ¥(1S)π^0) < 4.1\times 10^{-5}\ ({\rm 90%\ CL}). $

6 pages, 6 figures, submitted to PRD(RC)