Restoration of chiral symmetry and dilepton production at finite temperature

Vector-axial-vector mixing at finite temperature is reexamined from the viewpoint of a chiral rotation on the chiral SU(2)L × SU(2)RSU(2)V manifold. Using this idea, we discuss the possibility of observing a temperature dependent mass-shift in dilepton production from hot hadronic matter. It is shown that a new peak or bump corresponding to the axial-vector meson appears in addition to the ordinary ones due to vector mesons.