  A new algorithm for analytic continuation of noisy quantum Monte Carlo (QMC)
data from the Matsubara domain to real frequencies is proposed. Unlike the
widely used maximum-entropy (MaxEnt) procedure, our method is linear with
respect to input data and can therefore be applied to off-diagonal components
of a thermal Green's function, or to a self-energy function. The latter
possibility is used to analyze QMC results for the half-filled single-band
Hubbard model on a Bethe lattice at a low temperature. Our method qualitatively
resolves peaks near the inner edges of the Hubbard bands in the vicinity of a
Mott transition, whereas a MaxEnt procedure does not. An existence of such
structures has been clearly established before in a high-precision D-DMRG
calculation by Karski et al. We also analyze a stability of the new method
subject to changes of adjustable parameters.
