DILEPTON PRODUCTION FROM PION ANNIHILATION IN A REALISTIC DELTA-HOLE MODEL

Dilepton production from pi(+) pi(-) annihilation in nuclear matter is calculated ina simple two-level Delta-hole model and a more realistic model including both real pions and nucleon-hole and Delta-hole excit ations. Substantial enhancement of the dilepton yield is found in the invariant mass region M < 250 MeV/c(2) due to annihilation of noncolle ctive low-energy high-momentum nucleon-hole modes having a (very) smal l pion component. The inclusion of a finite temperature in the dispers ion relation does not affect the total dilepton yield much, although i t causes significant redistribution of the contributions from the vari ous combinations of pionic modes.