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

TL;DR

This paper reviews the properties of exotic XYZ mesons that do not fit the traditional quark-antiquark model, reports recent discoveries of charged bottomonium-like states, and presents a search for the H-dibaryon in Upsilon decays.

Contribution

It provides new experimental results on charged bottomonium-like states and a search for the H-dibaryon, expanding understanding of non-conventional hadronic matter.

Findings

Discovery of Z_b(10610)^+ and Z_b(10650)^+ states.

Observation of decay modes involving hidden bottomonium.

Search results for H-dibaryon production in Upsilon decays.

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.