Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The existence of a quantum phase transition in a Hubbard model on a
  quasi-one-dimentional two-leg ladder   A canonical transformation of a new type is offered as the mean for studying
properties of a system of strongly correlated electrons. As an example of the
utility of the transformation, it is used to demonstrate the existence of a
quantum phase transition in a Hubbard-like model on a quasi-one- dimensional
two-leg ladder.

32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph