Small field models of inflation that predict a tensor-to-scalar ratio $r=0.03$. (arXiv:1903.11820v1 [astro-ph.CO])

Small field models of inflation that predict a tensor-to-scalar ratio $r=0.03$. (arXiv:1903.11820v1 [astro-ph.CO])
<a href="http://arxiv.org/find/astro-ph/1/au:+Wolfson_I/0/1/0/all/0/1">Ira Wolfson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brustein_R/0/1/0/all/0/1">Ram Brustein</a>

Future observations of the cosmic microwave background (CMB) polarization are
expected to set an improved upper bound on the tensor-to-scalar ratio of
$rlesssim 0.03$. Recently, we showed that small field models of inflation can
produce a significant primordial gravitational wave signal. We constructed
viable small field models that predict a value of $r$ as high as $0.01$. Models
that predict higher values of $r$ are more tightly constrained and lead to
larger field excursions. This leads to an increase in tuning of the potential
parameters and requires higher levels of error control in the numerical
analysis. Here, we present viable small field models which predict $r=0.03$. We
further find the most likely candidate among these models which fit the most
recent Planck data while predicting $r= 0.03$. We thus demonstrate that this
class of small field models is an alternative to the class of large field
models. The BICEP3 experiment and the Euclid and SPHEREx missions are expected
to provide experimental evidence to support or refute our predictions.

Future observations of the cosmic microwave background (CMB) polarization are
expected to set an improved upper bound on the tensor-to-scalar ratio of
$rlesssim 0.03$. Recently, we showed that small field models of inflation can
produce a significant primordial gravitational wave signal. We constructed
viable small field models that predict a value of $r$ as high as $0.01$. Models
that predict higher values of $r$ are more tightly constrained and lead to
larger field excursions. This leads to an increase in tuning of the potential
parameters and requires higher levels of error control in the numerical
analysis. Here, we present viable small field models which predict $r=0.03$. We
further find the most likely candidate among these models which fit the most
recent Planck data while predicting $r= 0.03$. We thus demonstrate that this
class of small field models is an alternative to the class of large field
models. The BICEP3 experiment and the Euclid and SPHEREx missions are expected
to provide experimental evidence to support or refute our predictions.

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