Frontier Research

Deformed Starobinky inflation in Gravity's Rainbow -- Cosmic Inflation in Gravity's Rainbow space-time

Walailak Frontier 22, January 2020


Deformed Starobinky inflation in Gravity's Rainbow


Cosmic Inflation in Gravity's Rainbow space-time with deformed Starobinsky Model


The mathematical ground of general theory of relativity is based on a smooth manifold which breaks down when energies of probe reach the order of Planck energy. In this regard, one may expect a radically new shape of space-time, which implies a departure from the standard relativistic dispersion relation indicating that the system also incorporates a breaking of Lorentz invariance. As far as we concerned, a modification of the standard energy-momentum dispersion relation occurs in the ultraviolet regime of most of the quantum gravity theories. Likewise, as an effective theory of gravity, the Einstein general theory of gravity is valid in the low energy (IR) limit, while at very high energy regime (UV) the Einstein theory could in principle be improved. Additionally, the broken Lorentz invariance is considered in ultraviolet limit.

In principle, it is possible to connect the energy of probing particles and the energy-dependent space-time in the context of gravity’s rainbow. In the gravity’s rainbow framework, it is considered that particles with different energies are differently affected by the structure of space-time, depending on their wavelengths. Such modification in energy-momentum dispersion relation has been supported in the context of several topics, both astrophysical contexts, and cosmological implications.

In the context of gravity’s rainbow, the present work studied the deformed Starobinsky model. The author showed that the spectral index of curvature perturbation and the tensor-to-scalar ratio can be written in terms of the number of e-foldings and a rainbow parameter, and compared the predictions of the proposed models with Planck data. With the sizeable number of e-foldings and proper choices of parameters, the authors discovered that the predictions of the model are in good agreement with the Planck analysis. Interestingly, the upper limit and the lower limit of a rainbow parameter can also be quantified.



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