  We propose a novel explanation for the dilepton excess observed in heavy ion
collisions at invariant masses below 1 GeV. We argue that the presence of local
parity breaking due to a time-dependent isosinglet and/or isotriplet
pseudoscalar condensate substantially modifies the dispersion relation of
photons and vector mesons propagating in such a medium, changing the \rho~
spectral function and resulting in a potentially large excess of e+e- and
\mu+\mu- with respect to the theoretical predictions based in a 'cocktail' of
known hadronic processes. Possible signatures to prove or disprove this effect
are discussed.
