Correlation Inequalities for the Quantum XY Model

@article{Benassi2016CorrelationIF,
  title={Correlation Inequalities for the Quantum XY Model},
  author={Costanza Benassi and Benjamin Lees and Daniel Ueltschi},
  journal={Journal of Statistical Physics},
  year={2016},
  volume={164},
  pages={1157 - 1166}
}
We show the positivity or negativity of truncated correlation functions in the quantum XY model with spin 1/2 (at any temperature) and spin 1 (in the ground state). These Griffiths–Ginibre inequalities of the second kind generalise an earlier result of Gallavotti. 
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