It is pointed out that the diagonal amplitude of the E1-E1 chromo-electric interaction with soft gluon fields (chromo-polarizability) can be measured directly for the J/ψ and Υ resonances in the decays J/ψ → ππℓ+ℓ- and Υ → ππℓ +ℓ- with soft pions. For the J/ψ this amplitude is often discussed in connection with the J/ψ interaction with nuclear matter, while for the Υ the chromo-polarizability enters the estimates of the nonperturbative mass shift of the resonance relevant to precision determination of the b quark mass from the Υ mass.
Bibliographical noteFunding Information:
This work is supported in part by the DOE grant DE-FG02-94ER40823.
- Heavy quarkonia
- Nonperturbative QCD
- Soft pions