Spectral function and conductivity in the normal state of the cuprates: A spin fluctuation study

We study the spectral function A(k)(omega) and the optical conductivity sigma (1)(omega) for a system of fermions interacting with their collective spin fluctuations (the spin-fermion model), and apply the results to optimally doped cuprates in the normal state. We show that there is no qualitative distinction between hot and cold regions in the Brillouin zone-in both cases, then exists a wide range of frequencies where the width of the peak in A(k)(omega) scales linearly with omega. We demonstrate that sigma (1)(omega) is inversely linear in omega up to very high frequencies. We argue that the slopes of A(k)(omega) and sigma (1)(omega) agree quantitatively with the photoemission and optical data for Bi2212.