Hadronic correlation functions in the interacting instanton liquid.

Abstract

We study hadronic correlation functions in the interacting instanton liquid model, both at zero and nonzero temperature $T$. At zero $T$ we investigate the dependence of the correlators on the instanton ensemble, in particular the effect of the fermionic determinant. We demonstrate that quark-induced correlations between instantons are important, especially in the repulsive $\eta'$ and $\delta$-meson channels. We also calculate a large number of mesonic and baryonic correlation functions as a function of temperature. We find three different types of behavior as $T\to T_c$. The vector channels $\rho,a_1,\Delta$ show a gradual melting of the resonance contribution and approach free quark behavior near the chiral phase transition. The light pseudoscalars and scalars $\pi,\sigma$, as well as the nucleon show stable resonance contributions, probably even surviving above $T_c$. Correlation functions in the heavy scalar channels $\eta',\delta$ are enhanced as $T\to T_c$.