New Constraints on the running-mass inflation model

Abstract

We evaluate new observational constraints on the two-parameter scale-dependent spectral index predicted by the running-mass inflation model by combining the latest Cosmic Microwave Background (CMB) anisotropy measurements with the recent 2dFGRS data on the matter power spectrum, with Lyman $α$ forest data and finally with theoretical constraints on the reionization redshift. We find that present data still allow significant scale-dependence of $n$, which occurs in a physically reasonable regime of parameter space.

Figures (7)

• Figure 1: Primordial power spectrum on a logarithmic plot for the case of a scale invariant spectral index $n = 0.95$ (solid line) and $n=1.1$ (dashed-dotted line), and for the running mass prediction with $n_{\rm COBE} = 0.95$ and two different $n'_{\rm COBE}$, i.e. $n'_{\rm COBE} = 0.04$, corresponding to $c=0.1545, s=0.1295$ (upper dashed line) or $c=-0.1295, s=-0.1545$ (lower dashed line), and $n'_{\rm COBE} = 0.01$, corresponding to $c=0.08431, s=0.05931$ (upper dotted line) or $c=-0.05931, s=-0.08431$ (lower dotted line).
• Figure 2: Theoretical expected valued of the parameters $c, s$ for $N_{\rm COBE}=50$; the solid-line-hatched region is strongly excluded by naturality assumptions, while the dashed-line-hatched region is only weakly excluded. The dotted line shows the prediction for the simplest case, $s = e^{-c N_{\rm COBE}}$, where the linear approximation is valid up to the end of inflation, triggered by $\eta =1$.
• Figure 3: Theoretical expected valued of $z_R$ for $f\simeq 1$ as a function of $c$ for the case $s=c$ (dashed curve) and $s=c-0.05$ (dot-dashed curve). The cosmological parameters are chosen as $h=0.72$, $\omega_{cdm}=0.086$ and $\omega_b = 0.02$. We show also the reference line $z_R = 6$ (solid line).
• Figure 4: Likelihood contours in the $c-s$ plane. The gray contours are the $95 \%$ c.l. from the CMB analysis. The dark contours are from CMB+2dF analysis (Top), CMB+Lya (Center Panel), CMB+Reionization constraint (Bottom Panel).The straight lines corresponds to $n_{COBE}=0.8$,$1.0$ and $1.2$.
• Figure 5: Likelihood contours in the $(n_{COBE}-1)-(n'_{\rm COBE})$ plane for different datasets.