Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Complex-Temperature Properties of the 2D Ising Model for Nonzero
  Magnetic Field   We study the complex-temperature phase diagram of the square-lattice Ising
model for nonzero external magnetic field $H$, i.e. for $0 \le \mu \le \infty$,
where $\mu=e^{-2\beta H}$. We also carry out a similar analysis for $-\infty
\le \mu \le 0$. The results for the interval $-1 \le \mu \le 1$ provide a new
way of continuously connecting the two known exact solutions of this model,
viz., at $\mu=1$ (Onsager, Yang) and $\mu=-1$ (Lee and Yang). Our methods
include calculations of complex-temperature zeros of the partition function and
analysis of low-temperature series expansions. For real nonzero $H$, the inner
branch of a lima\c{c}on bounding the FM phase breaks and forms two
complex-conjugate arcs. We study the singularities and associated exponents of
thermodynamic functions at the endpoints of these arcs. For $\mu < 0$, there
are two line segments of singularities on the negative and positive $u$ axis,
and we carry out a similar study of the behavior at the inner endpoints of
these arcs, which constitute the nearest singularities to the origin in this
case. Finally, we also determine the exact complex-temperature phase diagrams
at $\mu=-1$ on the honeycomb and triangular lattices and discuss the relation
between these and the corresponding zero-field phase diagrams.

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The categories of this paper are: mtrl-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: supr-con
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The categories of this paper are: patt-sol
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The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-th