The accurate analytical and numerical calculations of the electronic band structure and ground state properties of strongly correlated electrons within the Hubbard model are performed by constructing convergent perturbation theory for general interaction strength and electron concentration. We test the developed perturbation approach about mean field solution in the extreme conditions of one di...

Although perturbation techniques are widely applied to analyze nonlinear problems in science and engineering, they are however so strongly dependent on small parameters appeared in equations under consideration that they are restricted only to weakly nonlinear problems. For strongly nonlinear problems which don’t contain any small parameters, perturbation techniques are invalid. So, it seems ne...

Abstract We study primordial cosmology with two scalar fields that participate in inflation at the same time, by coupling quantum gravity (i.e., theory R+R 2 +C fakeon prescription/projection for C ) to a field quadratic potential. show there exists perturbative regime can be described an asymptotically de Sitter, cosmic RG flow couplings. Since degrees of freedom mix nontrivial ways, adiabatic...

This paper is concerned with gradient estimation techniques for steady-state performance measures associated with regenerative stochastic processes. The principal emphasis is on the discussion of conditions under which likelihood ratio methods and infinitesimal perturbation analysis techniques are valid.

We describe output perturbation techniques that allow for a provable, rigorous sense of individual privacy. Examples where the techniques are effective span from basic statistical computations to sophisticated machine learning algorithms.