Breaking CMB degeneracy in dark energy through LSS
  The cosmic microwave background and large scale structure are complementary
probes to investigate the early and late time universe. After the current
accomplishment of the high accuracies of CMB measurements, accompanying
precision cosmology from LSS data is emphasized. We investigate the dynamical
dark energy models which can produce the same CMB angular power spectra as that
of the LCDM model with less than a sub-percent level accuracy. If one adopts
the dynamical DE models using the so-called Chevallier-Polarski-Linder (CPL)
parametrization, w = w0 + wa(1-a), then one obtains models (w0,wa)=
(-0.8,-0.767), (-0.9,-0.375), (-1.1,0.355), (-1.2,0.688) named as M8, M9, M11,
and M12, respectively. The differences of the growth rate, f which is related
to the redshift space distortions (RSD) between different DE models and the
LCDM model are about 0.2% only at z=0. The difference of f between M8 (M9, M11,
M12) and the LCDM model becomes maximum at z ~ 0.25 with -2.4 (-1.2, 1.2,
2.5)%. This is a scale-independent quantity. One can investigate the one-loop
correction of the matter power spectrum of each model using the standard
perturbation theory in order to probe the scale-dependent quantity in the
quasi-linear regime ({\it i.e.} k < 0.4 h/Mpc). The differences in the matter
power spectra including the one-loop correction between M8 (M9, M11, M12) and
the LCDM model for k= 0.4 h/Mpc scale are 1.8 (0.9, 1.2, 3.0)% at z=0, 3.0
(1.6, 1.9, 4.2)% at z=0.5, and 3.2 (1.7, 2.0, 4.5)% at z=1.0. The bigger
departure from -1 of w0, the larger the difference in the power spectrum. Thus,
one should use both the RSD and the quasi-linear observable in order to
discriminate a viable DE model among a slew of models which are degenerated in
CMB. Also we obtain the lower limit on w0 > -1.5 from the CMB acoustic peaks
and this will provide the useful limitation on phantom models.
