Inflation models after WMAP year three

TL;DR

The paper re-evaluates inflationary models in light of WMAP year-3 data, focusing on how the scalar spectral index $n$ and tensor-to-scalar ratio $r$ constrain slow-roll potentials. By expressing $n$ as a function of the number of $e$-folds $N$ and classifying models into small-field and large-field, it identifies which subfamilies remain viable: large-field models, and two families of small-field models with $p\le 0$ or $p\gtrsim 3$ in the potential $V\simeq V_0(1+\phi/\mu)^p$. The results show that a large fraction of models are ruled out at $>3\sigma$, while several classes survive, with further discrimination anticipated from Planck and Clover measurements. The analysis highlights that viable scenarios either involve large-field dynamics allowing observable $r$ or finely-tuned small-field constructions, guiding future model building and observational tests.

Abstract

The survey of models in astro-ph/0510441 is updated.For the first time, a large fraction of the models is ruled out at more than $3σ$.

Figures (4)

• Figure 1: The prediction (\ref{['nnew']}) for different $p$. The bold full line is the limit $|p|\to\infty$. Above it from top down are the lines $p=0$, $-2$ and $-4$, and below it from bottom up are the lines $p=3$, $4$ and $5$. The observational bounds from wmap3 are indicated.
• Figure 2: The regions excluded by the observational bounds from wmap3, for the parameter $p$ in the prediction (\ref{['nnew']}).
• Figure 3: The prediction (\ref{['nnew']}) for $N=54\pm 7$.
• Figure 4: The curved lines are the Natural Inflation predictions for $N=20$, $N=54$ and $N=75$, and the horizontal lines are the corresponding multi-component Chaotic Inflation predictions. The junction of each pair of lines corresponds to single-component Chaotic Inflation. The regions allowed by observation with various assumptions are taken from wmap3.