Studies of charmonium-like states at BABAR

TL;DR

This paper reviews various charmonium-like states observed at BABAR and Belle, discussing their production mechanisms, potential four-quark nature, and the conflicting evidence regarding the Z(4430)- state.

Contribution

It provides a comprehensive overview of experimental observations of charmonium-like states, highlighting the debate over the existence of the Z(4430)- and its possible tetraquark structure.

Findings

Observation of several charmonium-like states above D D̄ threshold.

Belle reports enhancements suggesting tetraquark candidates.

BABAR does not confirm the Z(4430)- existence.

Abstract

Several charmonium-like states above $D\bar{D}$ threshold have been discovered at the Belle and BABAR B-factories. Some of these states are produced via Initial State Radiation (e.g. Y(4260) and Y(4350)), and some are observed in B-meson decays (e.g. X(3872), and Y(3940)). The Belle observations of the enhancements in the $\psi(2S)\pi^-$ and $\chi_{c1}\pi^-$, i.e. the Z(4430)-, Z_1(4050)-, and Z_2(4250)-, have generated a great deal of interest, because such states must have minimum quark content $(c\bar{c}d\bar{u})$, i.e. these are candidate four-quark state. The BABAR Collaboration does not confirm the existinence of the $Z(4430)^-$.