Europhysics Conference on High-Energy Physics 2011

First observation of the hb(1P) and hb(2P) bottomonium states and study of Υ(5S) to Bottomonium decays

22 juil. 2011, 11:45

30m

Bayard (Alpes Congrès - Alpexpo)

Parallel session talk QCD

Orateur

Jean Wicht

Description

We report the observation of the $h_b(1P)$ and $h_b(1P)p$ spin-singlet bottomonium states produced in the reaction $e^{+}{e}^{-}\to h_b(1P)n{\pi }^{+}{\pi }^{-}$ with significances of $5.5\sigma$ and $11.2\sigma$, respectively. We find that $M[h_b(1P)]=(9898.25\pm {1.06}_{-1.07}^{+1.03})\mathrm{MeV}/c^2$ and $M[h_b(1P)p]=(10259.76\pm {0.64}_{-1.03}^{+1.43})\mathrm{MeV}/c^2$, which correspond to measurements of the P-wave hyperfine splittings$\mathrm{\Delta }{M}_{mHF}=(1.62\pm 1.52)\mathrm{MeV}/c^2$ and $({0.48}_{-1.22}^{+1.57})\mathrm{MeV}/c^2$, respectively. We also report measurements of the cross sections for $e^{+}{e}^{-}\to h_b(1P)n{\pi }^{+}{\pi }^{-}$ relative to the cross section for the $e^{+}{e}^{-}\to \mathrm{{\rm Y}}(2S){\pi }^{+}{\pi }^{-}$ reaction and examine the Dalitz plots of $\mathrm{{\rm Y}}$(5S)$\to \mathrm{{\rm Y}}$(nS)${\pi }^{+}{\pi }^{-}$ and $\mathrm{{\rm Y}}$(5S)$\to h_b$(mP)${\pi }^{+}{\pi }^{-}$ decays and search for resonant substructure. These results are obtained from a $121.4{\mathrm{f}\mathrm{b}}^{-1}$ data sample collected with the Belle detector near the $\mathrm{{\rm Y}}(5S)$ resonance at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.

Documents de présentation

Transparents

jwicht-hbzb-eps2011.pdf