Abstract
AbstractFor the subclass of Horndeski theory of gravity, we investigate the effects of reheating on the predictions of natural inflation. In the presence of derivative self-interaction of a scalar field and its kinetic coupling to the Einstein tensor, the gravitational friction to inflaton dynamics is enhanced during inflation. As a result, the tensor-to-scalar ratio r is suppressed. We place the observational constraints on a natural inflation model and show that the model is now consistent with the observational data for some plausible range of the model parameter $$\varDelta $$
Δ
, mainly due to the suppressed tensor-to-scalar ratio. To be consistent with the data at the $$1\sigma $$
1
σ
($$68\%$$
68
%
confidence) level, a slightly longer natural inflation with $$N_k\gtrsim 60$$
N
k
≳
60
e-folds, longer than usually assumed, is preferred. Since the duration of inflation, for any specific inflaton potential, is linked to reheating parameters, including the duration $$N_{re}$$
N
re
, temperature $$T_{re}$$
T
re
, and equation-of-state $$\omega _{re}$$
ω
re
parameter during reheating, we imposed the effects of reheating to the inflationary predictions to put further constraints. The results show that reheating consideration impacts the duration of inflation $$N_k$$
N
k
. If reheating occurs instantaneously for which $$N_{re}=0$$
N
re
=
0
and $$\omega _{re}=1/3$$
ω
re
=
1
/
3
, the duration of natural inflation is about $$N_k\simeq 57$$
N
k
≃
57
e-folds, where the exact value is less sensitive to the model parameter $$\varDelta $$
Δ
compatible with the CMB data. The duration of natural inflation is longer (or shorter) than $$N_k\simeq 57$$
N
k
≃
57
e-folds for the equation of state larger (or smaller) than 1/3 hence $$N_{re}\ne 0$$
N
re
≠
0
. The maximum temperature at the end of reheating is $$T_{re}^\text {max}\simeq 3\times 10^{15}$$
T
re
max
≃
3
×
10
15
GeV, which corresponds to the instantaneous reheating. The low reheating temperature, as low as a few MeV, is also possible when $$\omega _{re}$$
ω
re
is closer to 1/3.
Funder
National Research Foundation of Korea
Publisher
Springer Science and Business Media LLC
Subject
Physics and Astronomy (miscellaneous),Engineering (miscellaneous)
Cited by
4 articles.
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