**3.2.4. Power Spectrum in Nonlinear Galaxy Clustering**

Peacock (1997)
argued that the power spectrum in a small scale region
(*k*^{-1} < 3 *h*^{-1} Mpc),
where nonlinear effect is dominant, shows more power
than is expected in = 1
cosmological models. He showed that
the excess power is understood if the mass density is
0.3.