Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Description of Phases with Induced Hybridisation at Finite
  Temperatures   In an extended Falicov-Kimball model, an excitonic insulator phase can be
stabilised at zero temperature. With increasing temperature, the excitonic
order parameter (interaction-induced hybridisation on-site, characterised by
the absolute value and phase) eventually becomes disordered, which involves
fluctuations of both its phase and (at higher T) its absolute value. In order
to build an adequate mean field description, it is important to clarify the
nature of degrees of freedom associated with the phase and absolute value of
the induced hybridisation, and the corresponding phase space volume. We show
that a possible description is provided by the SU(4) parametrisation on-site.
In principle, this allows to describe both the lower-temperature regime where
phase fluctuations destroy the long-range order, and the higher temperature
crossover corresponding to a decrease of absolute value of the hybridisation
relative to the fluctuations level. This picture is also expected to be
relevant in other contexts, including the Kondo lattice model.

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The categories of this paper are: math
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th