Signature of the Quantum Gravity on the CMB
37
from the analysis of the study, it may be concluded that the quantum gravity effect
on the lensed BB mode correlation angular power spectrum of CMB with BK15 and
Planck 2018 joint data shows the quadratic and quartic chaotic inflationary models
cannot be ruled out at present.
6 Conclusion
The realization of the quantum nature of gravity both theoretically and experimentally
is an equally formidable challenging task. Though several approaches to quantum
gravity were proposed over the years, there is still a problem of lack of a consistent
theory. However, this does not prevent to explore the quantum gravity employing
appropriate experiment or else testing its consequence on the other phenomena. One
of the potential candidates to realize quantum gravity experimentally is the CMB
via inflation, provided presumably the energy scale of the inflation field possessed
higher value than the Planck scale. In such a higher energy scale, the inflation field
is assumed to be sensitive enough to quantum gravity. The recent result of the CMB
observation with Lyth bound suggests that the scale of the inflation field, in principle,
can take higher value than its standard case. Recently, it has been suggested that the
effective theory approach to quantum gravity and hence its effect on inflation is very
much suitable to observe the consequence of quantum gravity experimentally. The
effective theory approach to quantum gravity is one of the alternative approaches to
quantum gravity. Given the effective theory scenario, inflationary potential under the
consideration with the HDO parameter can have some impact on slow-roll parameters
of the inflation, and hence its consequence is expected to reflect on the BB mode
correlation angular spectrum of the CMB.
Based on the effective theory approach it is proposed that some of the disfavored
inflationary models may be reconsidered if the quantum gravity had played a key
role in the dynamics of the inflation. The extension of the effective theory approach
to the chaotic inflation showed that the tensor-to-scalar ratio of the model is lower
than its predicted value. The most effective tool to test any inflation model is to
examine the B-mode polarization of CMB due to the primordial gravitational waves
generated during inflation. Therefore, the BB mode angular power spectrum of CMB
can be used to examine inflation as well as quantum gravity. In the present work, we
investigated the quantum gravity effect on the BB mode correlation angular power
spectrum of CMB through the quadratic and quartic inflation models with BK15 and
Planck 2018 joint data.
We examined the effect of quantum gravity on the lensed BB mode correlation
angular power spectrum of CMB for the quadratic and quartic inflation for the combination (BK15 × BK15 −α BK15 × P)/(1 − α) of the autocorrelation spectrum of
BK15 at 150 GHz map and cross-correlation spectrum BK15 at 150 GHz map and
Planck 2018 at 353 GHz map with the cleaned dust contribution. From the study, it
can be observed that the lensed BB mode spectrum of CMB for the higher multipole
moments is out of the limit of the BK15 and Planck 2018 joint data for both inflation-
37
from the analysis of the study, it may be concluded that the quantum gravity effect
on the lensed BB mode correlation angular power spectrum of CMB with BK15 and
Planck 2018 joint data shows the quadratic and quartic chaotic inflationary models
cannot be ruled out at present.
6 Conclusion
The realization of the quantum nature of gravity both theoretically and experimentally
is an equally formidable challenging task. Though several approaches to quantum
gravity were proposed over the years, there is still a problem of lack of a consistent
theory. However, this does not prevent to explore the quantum gravity employing
appropriate experiment or else testing its consequence on the other phenomena. One
of the potential candidates to realize quantum gravity experimentally is the CMB
via inflation, provided presumably the energy scale of the inflation field possessed
higher value than the Planck scale. In such a higher energy scale, the inflation field
is assumed to be sensitive enough to quantum gravity. The recent result of the CMB
observation with Lyth bound suggests that the scale of the inflation field, in principle,
can take higher value than its standard case. Recently, it has been suggested that the
effective theory approach to quantum gravity and hence its effect on inflation is very
much suitable to observe the consequence of quantum gravity experimentally. The
effective theory approach to quantum gravity is one of the alternative approaches to
quantum gravity. Given the effective theory scenario, inflationary potential under the
consideration with the HDO parameter can have some impact on slow-roll parameters
of the inflation, and hence its consequence is expected to reflect on the BB mode
correlation angular spectrum of the CMB.
Based on the effective theory approach it is proposed that some of the disfavored
inflationary models may be reconsidered if the quantum gravity had played a key
role in the dynamics of the inflation. The extension of the effective theory approach
to the chaotic inflation showed that the tensor-to-scalar ratio of the model is lower
than its predicted value. The most effective tool to test any inflation model is to
examine the B-mode polarization of CMB due to the primordial gravitational waves
generated during inflation. Therefore, the BB mode angular power spectrum of CMB
can be used to examine inflation as well as quantum gravity. In the present work, we
investigated the quantum gravity effect on the BB mode correlation angular power
spectrum of CMB through the quadratic and quartic inflation models with BK15 and
Planck 2018 joint data.
We examined the effect of quantum gravity on the lensed BB mode correlation
angular power spectrum of CMB for the quadratic and quartic inflation for the combination (BK15 × BK15 −α BK15 × P)/(1 − α) of the autocorrelation spectrum of
BK15 at 150 GHz map and cross-correlation spectrum BK15 at 150 GHz map and
Planck 2018 at 353 GHz map with the cleaned dust contribution. From the study, it
can be observed that the lensed BB mode spectrum of CMB for the higher multipole
moments is out of the limit of the BK15 and Planck 2018 joint data for both inflation-