Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Order by disorder and phase transitions in a highly frustrated spin
  model on the triangular lattice   Frustration has proved to give rise to an extremely rich phenomenology in
both quantum and classical systems. The leading behavior of the system can
often be described by an effective model, where only the lowest-energy degrees
of freedom are considered. In this paper we study a system corresponding to the
strong trimerization limit of the spin 1/2 kagome antiferromagnet in a magnetic
field. It has been suggested that this system can be realized experimentally by
a gas of spinless fermions in an optical kagome lattice at 2/3 filling. We
investigate the low-energy behavior of both the spin 1/2 quantum version and
the classical limit of this system by applying various techniques. We study in
parallel both signs of the coupling constant J since the two cases display
qualitative differences. One of the main peculiarities of the J>0 case is that,
at the classical level, there is an exponentially large manifold of
lowest-energy configurations. This renders the thermodynamics of the system
quite exotic and interesting in this case. For both cases, J>0 and J<0, a
finite-temperature phase transition with a breaking of the discrete dihedral
symmetry group D_6 of the model is present. For J<0, we find a transition
temperature T^<_c/|J| = 1.566 +/- 0.005, i.e., of order unity, as expected. We
then analyze the nature of the transition in this case. While we find no
evidence for a discontinuous transition, the interpretation as a continuous
phase transition yields very unusual critical exponents violating the
hyperscaling relation. By contrast, in the case J>0 the transition occurs at an
extremely low temperature, T^>_c ~= 0.0125 J. Presumably this low transition
temperature is connected with the fact that the low-temperature ordered state
of the system is established by an order-by-disorder mechanism in this case.

9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
2
The categories of this paper are: math
3
The categories of this paper are: physics
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
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The categories of this paper are: hep-ex
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The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci