Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phase transition and spin-wave dispersion in quantum Hall bilayers at
  filling factor nu=1   We present an effective Hamiltonian for a bilayer quantum Hall system at
filling factor $\nu=1$ neglecting charge fluctuations. Our model is formulated
in terms of spin and pseudospin operators and is an exact representation of the
system within the above approximation. We analyze its low-lying excitations in
terms of spin-wave theory. Moreover we add to previous first-principle
exact-diagonalization studies concentrating on the quantum phase transition
seen in this system.

15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph