Pomeron-Odderon interference in production of pi^ + pi^- pairs in   ultraperipheral collisions
  In this contribution we discuss the production of two pion pairs in high energy photon collisions as they can be produced in ultraperipheral collisions at hadron colliders such as the Tevatron, RHIC or LHC. We find that charge asymmetries may reveal the existence of the perturbative Odderon. 
B. Pire, L. Szymanowski, F. Schwennsen, S. Wallon