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).