Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absence of a pseudogap in the in-plane infrared response of
  Bi2Sr2CaCu2O(8+d)   The ab-plane reflectance of Bi2Sr2CaCu2O(8+d) thin films was measured in the
30-25000 cm^(-1) range for one underdoped (Tc = 70 K), and one overdoped sample
(Tc = 63 K) as a function of temperature (10-300 K). We find qualitatively
similar behaviors in the temperature dependence of the normal-state infrared
response of both samples. Above Tc, the effective spectral weight, obtained
from the integrated conductivity, does not decrease when T decreases, so that
no opening of an optical pseudogap is seen. We suggest that these are
consequences of the pseudogap opening first in the k=(0, pi) direction,
according to ARPES, and of the in-plane infrared conductivity being mostly
sensitive to the k=(pi, pi) direction.

23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
17
The categories of this paper are: q-fin