Electroproduction of pion pairs
  We study hard exclusive electroproduction of two pions in the QCD factorization approach at next-to-leading order (NLO) in the strong coupling. The pion pair can be produced both in an isovector and in an isoscalar state. The angular distribution of the produced pion pairs allows one to project out a component that depends on the interference of the isovector and isoscalar channels. Using specific models for the involved generalized parton distributions and two-pion distribution amplitudes we investigate the angular distributions of the pion pair in NLO and compare them with HERMES data. The differences between the LO and NLO results are moderate and the agreement with data is satisfactory, though not perfect. Expecting new results from COMPASS collaboration we perform the calculation also for the COMPASS kinematics. 
D.Yu. Ivanov, M. Diehl, A. Schaefer, N. Warkentin