Exclusive Double Charmonium Production from $\Upsilon$ Decay

TL;DR

This paper predicts the branching ratios of $$ exclusive double charmonium production from $$ $$ decay using perturbative QCD, highlighting potential observability in future high-luminosity experiments and analyzing decay amplitude phases.

Contribution

It provides the first perturbative QCD predictions for $$ exclusive double charmonium production from $$ decay and discusses decay amplitude phases and interference effects.

Findings

Branching ratios are of order 10^{-6} for the first three $$ resonances.

The relative phase between strong and electromagnetic decay amplitudes is nearly orthogonal.

Resonance-continuum interference effects are analyzed near $$ resonances.

Abstract

The exclusive decay of $\Upsilon$ to a vector plus pseudoscalar charmonium is studied in perturbative QCD. The corresponding branching ratios are predicted to be of order $10^{-6}$ for first three $\Upsilon$ resonances, and we expect these decay modes should be discovered in the prospective high-luminosity $e^+e^-$ facilities such as super $B$ experiment. As a manifestation of the short-distance loop contribution, the relative phases among strong, electromagnetic and radiative decay amplitudes can be deduced. It is particularly interesting to find that the relative phase between strong and electromagnetic amplitudes is nearly orthogonal. The resonance-continuum interference effect for double charmonium production near various $\Upsilon$ resonances in $e^+e^-$ annihilation is addressed.