Reflection positivity and infrared bounds for quantum spin systems

Jakob E. Björnberg, Daniel Ueltschi

Published 2022-04-27Version 1

The method of reflection positivity and infrared bounds allows to prove the occurrence of phase transitions in systems with continuous symmetries. We review the method in the context of quantum spin systems. The novel aspect is a proof for long-range interactions that involve the Euclidean distance between sites.