Properties of non-q\bar{q} XYZ mesons and results of a search for the H-dibaryon

Abstract

A number of charmonium- and bottomonium-like meson states have been observed that have properties that do not match well to expectations for the simple quark-antiquark substructure suggested by the constituent quark model. Some of them are electrically charged and decay to final states containing hidden charmonum or bottomonium mesons and, thus, must contain at least four quarks. Common properties of these so-called XYZ mesons are partial widths for decays to hidden quarkonium states plus light hadrons that are much larger than corresponding partial widths for established quarkonium mesons. I review some recent results from the Belle experiment, including the recent discovery of two charged bottomium-like states, the Z_b(10610)^+ and Z_b(10650)^+, that decay to pi^+pi^- h_b(mS) (m=1,2) and pi^+ Upsilon(nS) (n=1,2,3) final states. In addition, I present recent Belle results from a search for H-dibaryon production in inclusive Upsilon(1S) and Upsilon(2S) decays.