A detailed investigation of the decay (2S)→π+π-(1S) has been made from 128 000 (2S) decays observed in the CLEO detector at the Cornell Electron Storage Ring (CESR). We find this branching ratio to be (19.1±1.2±0.6)%. The properties of the ππ system have been studied using 491 exclusive events of the type (2S)→π+π-(1S), (1S)→e+e-orμ+μ-. Assuming e-μ universality we find B((1S)→μ+μ-)=(2.84±0.18±0.20)%. A search for (2S)→η(1S) yields an upper limit of 1% at the 90% confidence level for this branching ratio. We have also searched for [(2S)or(3S)]→π+π-(1S) , (1S)→noninteracting particles.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)