Measurements of the Υ(10860) and Υ(11020) resonances via σ (e+e- → Υ(nS)π+π-)

Abstract

We report new measurements of the total cross sections for e+e-→(nS)π+π- (n=1, 2, 3) and e+e-→bb¯ from a high-luminosity fine scan of the region s=10.63-11.05 GeV with the Belle detector. We observe that the (nS)π+π- spectra have little or no nonresonant component and extract from them the masses and widths of (10860) and (11020) and their relative phase. We find M10860=(10891.1±3.2-1.7+0.6) MeV/c2 and Γ10860=(53.7-5.6 -5.4+7.1 +1.3) MeV and report first measurements M11020=(10987.5-2.5 -2.1+6.4 +9.0) MeV/c2, Γ11020=(61-19 -20+9 +2) MeV, and φ11020-φ10860=(-1.0±0.4-0.1+1.4) rad.