Novel spectral broadening from vector-axial-vector mixing in dense matter

The presence of baryonic matter leads to the mixing between transverse ρ and a1 mesons through a set of ωρa1-type interactions, which results in modification of the dispersion relation. We show that a clear enhancement of the vector spectral function appears below √(s)=mρ for small three-momenta of the ρ meson, and thus the vector spectrum exhibits broadening. We also discuss its relevance to dilepton measurements.