Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Modified natural inflation: A small single field model with a large
  tensor to scalar ratio   In this paper we explored in detail a phenomenological model of modified
single field natural inflation in light of recent cosmological experiments,
BICEP2. Our main goal is to construct an inflationary model which not only
predicts the important cosmological quantities such as $(n_s, r)$ compatible
with experimental observation, but also is consistent with the low energy
effective theory framework. Therefore, all the fundamental scale apart from
$M_p$ and quantities of our interest should be within the sub-Planckian region.
In order to achieve our goal we modify the usual single field natural
inflationary model by a specific form of higher derivative kinetic term called
kinetic gravity braiding (KGB). One of our guiding principles to construct such
a model is the constant shift symmetry of the axion. We have chosen the form of
the KGB term in such a way that it predicts the required value of $n_s\simeq
0.96$ and a large tensor to scalar ratio $r> 0.1$. Importantly for a wide range
of parameter space our model has sub-Planckian axion decay constant $f$ and the
scale of inflation $\Lambda$. However, the reheating after the end of inflation
limits the value of $f$ so that we are unable to get $f$ to be significantly
lower than $M_p$. Furthermore, we find sub-Planckian field excursion for the
axion field $\Delta \phi \simeq f$ for the sufficient number of e-folding
${\cal N} \gtrsim 50 $. We also discussed in detail about the natural
preheating mechanism in our model based on the recently proposed Chern-Simon
coupling. We found this gravity mediated preheating is very difficult to
achieve in our model. With our general analytic argument, we also would like to
emphasize that Chern-Simons mediated preheating is very unlikely to happen in
any slow roll inflationary model.

27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
11
The categories of this paper are: hep-lat
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph