THE SCALAR-ISOSCALAR SPECTRAL FUNCTION OF STRONG MATTER IN A LARGE N APPROXIMATION
The enhancement of the scalar-isoscalar spectral function near the two-pion threshold is studied in the framework of an effective linear σ model, using a large N approximation in the number of the Goldstone bosons. The effect is rather insensitive to the detailed T = 0 characteristics of the σ pole, it is accounted by a pole moving with increasing T along the real axis of the second Riemann sheet towards the threshold location from below.