Discontinuous Spontaneous-Symmetry-Breaking in the Microcanonical Ensemble

  title={Discontinuous Spontaneous-Symmetry-Breaking in the Microcanonical Ensemble},
  author={Hai-Jun Zhou},
Spontaneous-symmetry-breaking (SSB) is a macroscopic collective phenomenon occurring at phase transitions. Although deep understanding of SSB in the canonical statistical ensemble has been achieved, SSB in the microcanonical ensemble (with energy being the control parameter) has rarely been discussed. Here we study microcanonical SSB on the paradigmatic $Q$-state Potts model ($Q\! \geq\! 3$). The Bethe-Peierls mean field theory predicts a discontinuous phase transition in regular random graphs… 

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