Mathematical Physics Seminar

We consider the quantum ferromagnetic Heisenberg model in three
dimensions, for all spins S≥1/2. We rigorously prove the validity of the
spin-wave approximation for the excitation spectrum, at the level of the
first non-trivial contribution to the free energy at low temperatures. The
proof combines a bosonic representation of the model introduced by
Holstein & Primakoff with probabilistic estimates, localization bounds and
functional inequalities. (Joint work with Michele Correggi and Alessandro
Giuliani)