Inverse scattering of Canonical systems and their evolution

In this work we present an analogue of the inverse scattering for Canonical systems using theory of vessels and associated to them completely integrable systems. Analytic coefficients fits into this setting, significantly expanding the class of functions for which the inverse scattering exist. We also derive an evolutionary equation, arising from canonical systems, which describes the evolution of the logarithmic derivative of the tau function, associated to these systemsComment: arXiv admin note: substantial text overlap with arXiv:1303.532

Dually-charged mesoatom on the space of constant negative curvature

The discrete spectrum solutions corresponding to dually-charged mesoatom on the space of constant negative curvature are obtained. The discrete spectrum of energies is finite and vanishes, when the magnetic charge of the nucleus exceeds the critical value.Comment: 15 pages, LaTe

The self-energy of improved staggered quarks

We calculate the fermion self-energy at O(alpha_s) for the Symanzik improved staggered fermion action used in recent lattice simulations by the MILC collaboration. We demonstrate that the algebraic approach to lattice perturbation theory, suggested by us recently, is a powerful tool also for improved lattice actions.Comment: 6 page

On the singularity of the irreducible components of a Springer fiber in sl(n)

Let ${\mathcal B}_u$ be the Springer fiber over a nilpotent endomorphism $u\in End(\mathbb{C}^n)$. Let $J(u)$ be the Jordan form of $u$ regarded as a partition of $n$. The irreducible components of ${\mathcal B}_u$ are all of the same dimension. They are labelled by Young tableaux of shape $J(u)$. We study the question of singularity of the components of ${\mathcal B}_u$ and show that all the components of ${\mathcal B}_u$ are nonsingular if and only if $J(u)\in\{(\lambda,1,1,...), (\lambda_1,\lambda_2), (\lambda_1,\lambda_2,1), (2,2,2)\}$.Comment: 19 page