Heavy Quarkonia Spectroscopy and Decays

TL;DR

This paper reviews recent experimental progress in heavy quarkonia spectroscopy and decays, highlighting new discoveries and measurements that test theoretical predictions and improve understanding of non-perturbative QCD effects.

Contribution

It provides a comprehensive review of recent experimental findings in heavy quarkonia, including the first detection of an L=2 state and new decay transition measurements.

Findings

First stable L=2 quarkonium state detected

First non-pionic hadronic transition in Upsilon system observed

Measurement of chi_cJ --> Lambda Lambdabar decay

Abstract

The experimental status of stable bound states made out of heavy quarks is reviewed. The need for a way to deal with the non-perturbative transitions involved calls for precision measurements on one hand, and for discovery of as yet undetected states to confirm predictions on the other. In this article, recent experimental contributions to heavy quarkonia spectroscopy and decay will be reviewed, mostly from data analyzed by the BES and CLEO collaborations. The most dramatic recent discoveries include the detection of the first stable L=2 state, and a first non-pionic hadronic transition in the Upsilon system, and a first measurement of chi_cJ --> Lambda Lambdabar. Scans of the psi' and Upsilon(1,2,3S) resonances are used to add information on partial and total decay widths.