Study ofπ+π−transitions from the Υ(3S)

Abstract

We have investigated the transitions Υ(3S)→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$Υ(1S) and Υ(3S)→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$Υ(2S) and the cascade process Υ(3S)→Υ(2S)+X, Υ(2S)→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$Υ(1S), both in the exclusive decay mode where the daughter Υ state decays into two leptons, and in the inclusive decay mode where the daughter Υ state decays hadronically. Results are presented on branching fractions and the properties of the ${\pi }^{+}$ ${\pi }^{\mathrm{-}}$ system. Possible evidence for the transition Υ(3S)→${\pi }^{+}$ ${\pi }^{\mathrm{-}}$Υ${(1\mathrm{}}^1$ $P_1$) is presented.