We review correlation inequalities of truncated functions for the classical and quantum XY models. A consequence is that the critical temperature of the XY model is necessarily smaller than that of the Ising model, in both the classical and quantum cases. We also discuss an explicit lower bound on the critical temperature of the quantum XY model.
|Title of host publication||Advances in Quantum Mechanics|
|Subtitle of host publication||Contemporary Trends and Open Problems|
|Editors||Alessandro Michelangeli, Gianfausto Dell'Antonio|
|Number of pages||17|
|Publication status||Published - Sep 2017|
|Name||Springer INdAM Series|