Girish Kumar Chakravarty

Power law Starobinsky model of inflation from no-scale SUGRA

Abstract We consider a power law 1 M 2 R β correction to Einstein gravity as a model for inflation. The interesting feature of this form of generalization is that small deviations from the Starobinsky limit β = 2 can change the value of tensor-to-scalar ratio from r ∼ O ( 10 − 3 ) to r ∼ O ( 0.1 ) . We find that in order to get large tensor perturbation r ≈ 0.1 as indicated by BKP measurements, we require the value of β ≈ 1.83 thereby breaking global Weyl symmetry. We show that the general R β model can be obtained from a SUGRA construction by adding a power law ( Φ + Φ ¯ ) n term to the minimal no-scale SUGRA Kahler potential. We further show that this two-parameter power law generalization of the Starobinsky model is equivalent to generalized non-minimal curvature coupled models of the form ξ ϕ a R b + λ ϕ 4 ( 1 + γ ) and thus the power law Starobinsky model is the most economical parametrization of such models.

Higgs Inflation in

We generalize the scalar-curvature coupling model

f(\Phi,R)

{\xi \Phi^2 R}

Theory

of Higgs inflation to

Dilaton assisted two-field inflation from no-scale supergravity

{\xi \Phi^a R^b}

Constraints on cosmological viscosity and self interacting dark matter from gravitational wave observations

to study inflation. We compute the amplitude and spectral index of curvature perturbations generated during inflation and fix the parameters of the model by comparing these with the Planck

Plateau Inflation in SUGRA-MSSM

+

Plateau inflation in R-parity violating MSSM

WP data. We find that if the scalar self coupling

Testing theories of gravity and supergravity with inflation and observations of the cosmic microwave background

\lambda

The power law Starobinsky model

is in the range