COMPARISON OF 32-SITE EXACT DIAGONALIZATION RESULTS AND ARPES SPECTRAL FUNCTIONS FOR THE ANTIFERROMAGNETIC INSULATOR SR2CUO2CL2

We explore the success of various versions of the one-band t-J model i n explaining the full spectral functions found in angle-resolved photo emission spectra for the prototypical, quasi-two-dimensional, tetragon al, antiferromagnetic insulator Sr2CuO2Cl2. After presenting arguments justifying our extraction of A(k,omega) from the experimental data, w e rely on exact-diagonalization results from studies of a square 32-si te lattice, the largest cluster for which such information is presentl y available, to perform this comparison. Our work leads us to believe that (i) a one-band model that includes hopping out to third-nearest n eighbors, as well three-site, spin-dependent hopping, can indeed expla in not only the dispersion relation, but also the quasiparticle lifeti mes-only in the neighborhood of k=(pi/2,0) do we find disagreement; (i i) an energy-dependent broadening function, Gamma(E)=Gamma(0)+AE, is i mportant in accounting for the incoherent contributions to the spectra l functions.