Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vibrational excitations in systems with correlated disorder   We investigate a $d$-dimensional model ($d$ = 2,3) for sound waves in a
disordered environment, in which the local fluctuations of the elastic modulus
are spatially correlated with a certain correlation length. The model is solved
analytically by means of a field-theoretical effective-medium theory
(self-consistent Born approximation) and numerically on a square lattice. As in
the uncorrelated case the theory predicts an enhancement of the density of
states over Debye's $\omega^{d-1}$ law (``boson peak'') as a result of
disorder. This anomay becomes reinforced for increasing correlation length
$\xi$. The theory predicts that $\xi$ times the width of the Brillouin line
should be a universal function of $\xi$ times the wavenumber. Such a scaling is
found in the 2d simulation data, so that they can be represented in a universal
plot. In the low-wavenumber regime, where the lattice structure is irrelevant
there is excellent agreement between the simulation at small disorder. At
larger disorder the continuum theory deviates from the lattice simulation data.
It is argued that this is due to an instability of the model with stronger
disorder.

20
The categories of this paper are: acc-phys
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph