Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Constraints on dark energy and quintessence with a comoving standard
  ruler applied to 2dF quasars   Structures on very large scales (> 100 Mpc) have negligible peculiar motions,
and are thus roughly fixed in comoving space. We looked for significant peaks
at very large separation in the two-point correlation function -- corrected for
redshift selection effects -- of a well convered subsample of 2378 quasars of
the recently released 10k sample of the 2dF quasar survey. Dividing our sample
in three redshift intervals, we find a peak at 244/h Mpc, which is perfectly
comoving for a restricted set of cosmological parameters, namely Omega_m =
0.25+/-0.15 and Omega_Lambda=0.65+/-0.35 (both at 95% confidence). Assuming a
flat Universe, we constrain the quintessence parameter w_Q < -0.35 (95%
confidence). We discuss the compatibility of our analysis with possible peaks
in the power spectrum.

19
The categories of this paper are: eess
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph