Measurement of interference between electromagnetic and strong amplitudes in ψ(2S) decays to two pseudoscalar mesons

Using a sample of 3.08×106 ψ(2S) decays collected at s=3.686GeV with the CLEO detector at the Cornell Electron Storage Ring, we have measured the branching fractions for ψ(2S) decays to pseudoscalar pairs π+π-, K+K- and KS0KL0. We obtain B(ψ(2S)→π+π-)<2.1×10-5 (90% C.L.), B(ψ(2S)→K+K-)=(6.3±0.6(stat)±0.3(syst))×10- 5, and B(ψ(2S)→KS0KL0)=(5.8±0.8(stat)±0.4(syst)) ×10-5. The branching fractions allow extraction of the relative phase Δ=(95±15)° and strength ratio R=(2.5±0.4) of the three-gluon and one-photon amplitudes for these modes.