Observation of a new structure near 10.75 GeV in the energy dependence of the e cross sections

e 断面積のエネルギー依存性測定における10.75GeV付近の新しい構造の観測

Mizuk, R.*; 谷田 聖   ; Belle Collaboration*; 他181名*

Mizuk, R.*; Tanida, Kiyoshi; Belle Collaboration*; 181 of others*

We report a new measurement of the () cross sections at energies from 10.52 to 11.02 GeV using data collected with the Belle detector at the KEKB asymmetric-energy collider. We observe a new structure in the energy dependence of the cross sections; if described by a Breit-Wigner function its mass and width are found to be MeV/ and MeV, where the first error is statistical and the second is systematic. The global significance of the new structure that includes a systematic uncertainty is 6.7 standard deviations. We also find evidence for the process at the energy 10.52 GeV, which is below the threshold.