Using a 4.19 fb-1 data sample collected with the CLEO II detector at the Cornell Electron Storage Ring, we have searched for dipion transitions between pairs of Y resonances at center of mass energies Ec.m. = 10.58 GeV and Ec.m. = 10.52GeV. We obtain the 90% confidence level upper limits B(Υ(4S) →Υ (2S) π+π-)<3.9×10-4 and B(Υ(4S)→Υ(1S)π+π -)<1.2×10-4. We also observe the transitions Υ(2S)→Υ(1S)π+π-, Υ(3S)→Υ(2S)π+π-, and Υ(2S)→Υ(1S)π+π-, from which we measure the cross sections for the radiative processes e+e-→Υ(2S)γ and e+e-→Υ(2S)γ. We obtain σee→Υ(3S)γ = (17.8±3.0±1.7)pb and ee→Υ(2S)γ = (15.5±1.3±1.4) pb at Ec.m. = 10.58 GeV, and ee→Υ(3S)γ = (27.3 ±5.0±2.6) pb and ee→Υ(2S)γ = (16.3±1.8±1.5) pb at Ec.m. = 10.52 GeV, which we compare with theoretical predictions.
|Number of pages||8|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|Publication status||Published - 1999 Mar 1|
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics