出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：We review recent studies on exotic states at the Belle experiment. The results include: (1) The measurement of the cross sections of γγ →ωϕ , ϕϕ , and ωω for masses that range from thresh- old to 4.0 GeV. In addition to signals from well established spin-zero and spin-two charmonium states, there are clear resonant structures below charmonium threshold, which have not been pre- viously observed. We report a spin-parity analysis for the new structures; (2) No X(3872) signal is observed in ηJ/ψ or γχc1 mode in B decays. A narrow peak at 3823.5 MeV/c2 (named as ψ2) to γχc1 with a significance of 4.2 standard deviations including systematic uncertainty is ob- served in B± →K±γχc1; (3) The bottomonium states hb(1P), hb(2P) and ϒ(1D) are observed in the reaction e+e− →π+π− +X; (4) The observation of two narrow charged structures (named as Zb(10610) and Zb(10650)) in the mass spectra of the π±ϒ(nS)(n = 1,2,3) and π±hb(mP) (m = 1,2) pairs that are produced in association with a single charged pion in Y(5S) decays.
