A study of a non-unitary statistical model, super spin chains and intersecting loops

by Etienne Granet (ENS Paris, CEA Saclay)

Location: CYCL04, Louvain-la-Neuve
Time: Wednesday November 7, 2018 at 15:00

We study a non-unitary spin chain with orthosymplectic symmetry that generalizes the \(O(N)\) model to any positive or negative integer N. The lack of unitarity allows a stable massless Goldstone phase to appear, otherwise forbidden by the Mermin-Wagner theorem, that is described by a supersphere sigma model. On the 2D lattice it is represented as a dense loop model with loop weight \(N\) in which crossings are allowed. Unlike the usual \(O(N)\) loop model, the presence of crossings makes the model flow to a different regime where correlations involve logarithms. We compute these logarithmic critical exponents with field theory and the Bethe ansatz.