  Generically,the classical evolution of the inflaton has a brief fast roll
stage that precedes the slow roll regime. The fast roll stage leads to a purely
attractive potential for the curvature and tensor perturbations (this potential
is purely repulsive in slowroll). This attractive potential depresses the CMB
quadrupole moment for the curvature and B-mode spectra. A single new
cosmological parameter emerges: the comoving wavenumber k_1 characteristic
scale of this attractive potential.k_1 happens to exit the horizon precisely at
the transition from fast to slowroll.The fastroll stage dynamically modifies
the initial power spectrum by a transfer function D(k). We compute D(k) by
solving the inflaton evolution equations. D(k) suppresses the primordial power
for k < k_1 and enjoys the scaling property D(k) = Psi(k/k_1) where Psi(x) is
an universal function. We perform a MCMC analysis of the WMAP/SDSS data
including the fast-roll stage and find k_1 = 0.266/Gpc. The quadrupole mode k_Q
= 0.242/Gpc exits the horizon 1/10 of an efold before k_1. We compare the
fastroll fit with a fit with a sharp lower cutoff on the primordial power.
Fastroll provides a slightly better fit than a sharp cutoff for the TT,TE and
EE modes.Moreover, our fits provide non-zero lower bounds for r, while for the
other cosmological parameters we essentially get those of the LCDM model. The
fact that k_Q exits the horizon before the slowroll stage implies an upper
bound in the total number of efolds N_{tot} during inflation.Combining this
with estimates during the radiation dominated era we obtain N_{tot} ~ 66, with
the bounds 62 < N_{tot} < 82.We repeated the analysis with the
WMAP-5/ACBAR-2007/SDSS data confirming the overall picture.
