Technically "natural'' means that the flatness of the potential is protected by a symmetry - here the shift symmetry of a Nambu-Goldstone mode (Freese et al. 1990).

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http://lambda.gsfc.nasa.gov

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...2002)

Very recently, Boughn & Crittenden (2003) claim to have detected a large-scale correlation between the WMAP and HEAO-1 maps at the 2.4-2.8 $\sigma$ level, which is surprising since the WMAP and COBE maps are quite consistent. They also find a correlation between WMAP and the NVSS survey of radio galaxies at the 1.8-2.3 $\sigma$ level. Nolta et al. (2003) confirm the latter finding and reject a $\Lambda = 0$ universe at 95% c.l. However Myers et al. (2003) have found significant contamination of the WMAP data by NVSS sources which can account for the observed correlation. Fosalba & Gaztañaga (2003) also find a correlation, twice as strong as the expected signal, between WMAP and the APM galaxy survey.

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...2002)

Their best-fit is $\beta = 0.49 \pm 0.09$ at the mean redshift of the survey: $z \approx 0.17$ . Combined with the estimate of $b = 1.04 \pm 0.11$ from analysis of the bispectrum of 2dFGRS on scales $k\sim (0.1-0.5)~h/$ Mpc (Verde et al. 2002), this yields $\Omega_{\rm m}(z=0) = 0.23 \pm 0.09$ . However, this constraint on the bias, obtained by an elaborate statistical analysis, may not be reliable if the biasing process is more complicated than envisaged in this work.

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