New model of axion monodromy inflation and its cosmological implications
  We propose a new realization of axion monodromy inflation in which axion
monodromy arises from torsional cycles in a type IIB compactification. A class
of monomial potentials is obtained with specific values for the power index.
Moreover, the inflaton mass changes profile due to the couplings between
various fields after compactification. Consequently, the potential obtains a
step-like profile at some critical scale. We study the cosmological
implications of one concrete realization of this model. At the background
level, it realizes a sufficiently long inflationary stage, which allows for the
violation of the slow-roll conditions for a short period of time when the
inflaton is close to the critical scale. Accordingly, the Hubble horizon is
perturbed and affects the dynamics of primordial cosmological perturbations. In
particular, we analyze the angular power spectrum of B-mode polarization and
find a boost on very large scales. We also find that the amplitude of scalar
perturbations is suppressed near the critical scale. Thus our model provides an
interpretation for the low-$\ell$ suppression of temperature anisotropies in
the CMB power spectrum. We examine these effects and confront the model to
observations.
