Inflation models, spectral index and observational constraints
DESY Theory Group, Notkestrasse 85
22603 Hamburg, Germany
We have evaluated the observational constraints on the spectral
index $n$, in the context of a $\Lambda$CDM model.
For $n$ scale-independent, as predicted
by most models of inflation, present data require
$n\simeq 1.0 \pm 0.1$ at the 2-$\sigma$ level.
We have also studied the two-parameter scale-dependent spectral
index, predicted by running-mass inflation models. Present data
allow significant variation of $n$ in this case, within the
theoretically preferred region of parameter space