Critical scaling for spectral functions

Abstract

We study real-time scalar $\ddot{I}{•}^4$-theory in 2+1 dimensions near criticality. Specifically, we compute the single-particle spectral function and that of the $s$-channel four-point function in and outside the scaling regime. The computation is done with the spectral functional Callan-Symanzik equation, which exhibits manifest Lorentz invariance and preserves causality. We extract the scaling exponent $\hat{I}\cdot$ from the spectral function and compare our result with that from a Euclidean fixed point analysis.

17 pages, 7 figures