Recent Progress and Puzzles in Charmonium Physics

TL;DR

This paper reviews recent experimental discoveries in charmonium physics, highlighting new states and resonances that challenge existing models and indicating ongoing puzzles in understanding ccbar bound states.

Contribution

It summarizes recent experimental results from B-factories, including new charmonium-like states and resonances, emphasizing unresolved issues in the charmonium model.

Findings

Discovery of X(3872) and other new states

Identification of four resonances in ISR decays

Challenges to the traditional charmonium model

Abstract

While the charmonium model has been effective in describing ccbar bound mesons, there have been many recently discovered charmonium-like states it cannot accommodate. Here I provide a review of recent results from the B-factories including the X(3872), three new particles in the mass range near 3.93 GeV, and four new resonances in initial state radiation (ISR) decays.