Observation of transverse polarization asymmetries of charged pion pairs   in e+e- annihilation near sqrt 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 \times 106 pi+pi- pairs and was collected at and near the ?(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. 
A. Vossen, R. Seidl, I. Adachi, H. Aihara, T. Aushev, V. Balagura, W.   Bartel, M. Bischofberger, A. Bondar, M. Bra\v{c}ko, ...
hep-ex