6 papers
Lindstedt series for periodic solutions of beam equations with quadratic and velocity dependent nonlinearities
Vieri Mastropietro, Michela Procesi
We prove the existence of small amplitude periodic solutions, for a large Lebesgue measure set of frequencies, in the nonlinear beam equation with a weak quadratic and velocity dep…
Peierls instability with electron-electron interaction: the commensurate case
Vieri Mastropietro
We consider a quantum many-body model describing a system of electrons interacting with themselves and hopping from one ion to another of a one dimensional lattice. We show that th…
Renormalization Group, hidden symmetries and approximate Ward identities in the XYZ model, II
G. Benfatto, V. Mastropietro
An expansion based on renormalization group methods for the spin correlation function in the z direction of the Heisenberg-Ising XYZ chain with an external magnetic field directed…
Renormalization group for the XYZ model
V. Mastropietro
We study in a rigorous way the XYZ spin model by Renormalization Group methods.
Peierls instability for the Holstein model
G. Benfatto, G. Gentile, V. Mastropietro
We consider the static Holstein model, describing a chain of Fermions interacting with a classical phonon field, when the interaction is weak and the density is a rational number.…
Hamilton-Jacobi equation, heteroclinic chains and Arnol'd diffusion in three time scales systems
Giovanni Gallavotti, Guido Gentile, Vieri Mastropietro
Interacting systems consisting of two rotators and a point mass near a hyperbolic fixed point are considered, in a case in which the uncoupled systems have three very different cha…