Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Charge Density Waves and Bond Order Waves in a quarter filled extended
  Hubbard ladder   We investigate the phase diagram of a quarter filled Hubbard ladder with
nearest-neighbor Coulomb repulsion using bosonization and renormalization group
approach. Focusing on the strong-repulsion regime, we discuss the effect of an
interchain exchange interaction J and interchain repulsion V on the possible
ground states of the system and charge order configurations. Since the spin
excitations always possess a gap, we find competing bond-order wave and charge
density wave phases as possible ground states of the ladder model. We discuss
the elementary excitations in these various phases and point an analogy between
the excitations on some of these phases and those of a Kondo-Heisenberg
insulator. We also study the order of the quantum phase transitions between the
different ground states of the system. We obtain second order transitions in
the Ising or SU(2)_2 universality class or first order transitions. We map the
complete phase diagram in the J-V plane by integrating perturbative
renormalization-group equations. Finally, we discuss the effect of doping away
from half-filling and the effect of an applied magnetic field.

3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin