16 papers
A Criterion for Ferromagnetism in the Isotropic Quantum Heisenberg Model
Paul Federbush
A criterion for ferromagnetism is presented suggesting a line of proof to rigorously establish the phase transition. Spectral information will be required in certain invariant subs…
A Polymer Expansion for the Random Walk on the Permutation Group Associated to the Quantum Heisenberg Ferromagnet
Paul Federbush
For a long time one has associated to the Quantum Heisenberg Ferromagnet on a lattice, a random walk on the permutation group of the lattice vertices. We here present a polymer exp…
Single Site Spin Expectation for the Imaginary Time Heisenberg Ferromagnet Wave Function, Numerical Approximation and Theoretical Argument
Paul Federbush
Certain approximations for the spin expectations have been studied both numerically and theoretically. Approximations are constructed using solutions of the lattice heat equation.…
For the Quantum Heisenberg Ferromagnet, Tao to the Proof of a Phase Transition
Paul Federbush
We present the outline of a proof for the 3-d phase transition which we hope to carry forth. At the same time this paper provides some physical understanding of the phase transitio…
For the Quantum Heisenberg Ferromagnet, a Polymer Expansion and its High T Convergence
Paul Federbush
We let Psi_0 be a wave function for the Quantum Heisenberg ferromagnet sharp i sigma_zi and Psi_mu = exp(-mu*H)Psi_0. We study expectations similar to the form <Psi_mu,(sigma_zi)Ps…
For the Quantum Heisenberg Ferromagnet, Some Conjectured Approximations
Paul Federbush
We present some conjectured approximations for spin expectations in a Quantum Heisenberg system. The conjectures are based on numerical experimentation, some theoretical insights a…