Puzzles in charmonium decays

TL;DR

This paper investigates how intermediate hadron loop transitions influence puzzles in charmonium decays, such as non-D D̄ decays and the ρπ puzzle, highlighting non-perturbative effects and HSR violations.

Contribution

It presents recent progress in understanding charmonium decay puzzles through the role of open charm effects and intermediate hadron loops.

Findings

Intermediate hadron loops significantly affect charmonium decay patterns.

Non-perturbative mechanisms contribute to observed decay anomalies.

The study offers insights into helicity-selection-rule violations.

Abstract

The open charm effects via intermediate hadron loop transitions seem to play a crucial role in the understanding of several existing "puzzles" in charmonium exclusive decays, such as the $\psi(3770)$ non-$D\bar{D}$ decays, and "$\rho\pi$ puzzle" etc. In the charmonium energy region, non-perturbative mechanisms could be still sizeable, and as a consequence the intermediate hadron loop transitions also provide a mechanism for the helicity-selection-rule (HSR) violation. We report our recent progress on those existing puzzles.