SP Seminar @SISSA Via Bonomea 265 Rm128 - Tuesday 20 November at 11:00 am - P. GRANET

[CM Section]

Joint ICTP/SISSA Statistical Physics Seminar

Tuesday 20 November at 11:00 a.m.
SISSA, Via Bonomea 265, Room 128

E. GRANET (CEA-Saclay, ENS Paris,France)

'A Study of a Non-Unitary Statistical Model: Super Spin Chains and
Intersecting Loops'

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.