Observation of Transverse Polarization Asymmetries of Charged Pion Pairs in e+e- Annihilation near √s=10.58 GeV

The interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e(+)e(-) annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered pi(+)pi(-) pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb(-1) data sample that contains 711 x 10(6) pi(+)pi(-) pairs and was collected at and near the Y(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider.