Marginally Deformed Starobinsky Gravity

Abstract

We show that quantum-induced marginal deformations of the Starobinsky gravitational action of the form $R^{2(1-\alpha )}$, with $R$ the Ricci scalar and $\alpha$ a positive parameter, smaller than one half, can account for the recent experimental observations by BICEP2 of primordial tensor modes. We also suggest natural microscopic (non) gravitational sources of these corrections and demonstrate that they lead generally to a nonzero and positive $\alpha$. Furthermore we argue, that within this framework, the tensor modes probe theories of grand unification with a large scalar field content.

5 pages, 1 figure, 2 columns

References in corpus (3)

• Toward an Understanding of Foreground Emission in the BICEP2 Region
• The Imaginary Starobinsky Model
• Conformally flat FRW metrics

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