SEMINAR      Tuesday, March 30th 2004 - h. 12:00  High Energy Physics Building, Aula A1     I. IVANOV  I.N.F.N., G.C. Cosenza   Charge asymmetries in dipion production at HERA: search for the odderon and measurement of the Pomeron phase Abstract     The dominant mechanism of diffractive production of pi+pi- pairs at HERA is the rho-meson production via the Pomeron exchange. These pi+pi- pairs are in the C-odd state. The other mechanisms -- one-photon exchange and the odderon exchange -- lead to C-even pi+pi- pairs. They make negligible contributions to the integrated cross section, but can be seen via charge asymmetries. We discuss a very promising physics potential of such charge asymmetry measurements at HERA. We illustrate the proposal with two examples: a possibility to discover the odderon and to measure the Pomeron phase in current experiments at HERA.