Possibility of the odderon discovery via observation of charge asymmetry   in the diffractive pi+pi- production at HERA
  The interference between the Pomeron and possible odderon mechanisms of diffractive pi+pi- photoproduction results in charge asymmetry of the produced pions. The observation of charge asymmetry of pions at moderate M_{pi+pi-} will be an undoubted signal of odderon existence. To make numeral estimates more definite, we limit ourselves by the region M_{pi+pi-} = 1.1 -- 1.5 GeV, where in the odderon mechanism of dipion production, the production via single f_2(1270) resonance is expected to be dominant. We find a very statistically significant effect of the odderon induced charge asymmetry even with very modest estimates for the f_2 photoproduction cross section (without referring to any particular model of the odderon). 
I.F. Ginzburg (1), I.P. Ivanov (1 and 2), N.N. Nikolaev (2 and 3) ((1)   Sobolev Institute of Mathematics, Novosibirsk, Russ...