Iberian Strings Meetings 

19/01/2021, 11:30 — 12:00 — Online
Pablo Cano, KU Leuven

Novel higher-curvature variations of $R^2$ inflation

Higher-curvature corrections to the gravitational action are a definite prediction of string theory and they may play an important role in the early universe. Indeed, one of the most successful inflationary scenarios is based on the Lagrangian $R+R^2$, but the effect of more general corrections is not yet fully understood. In this talk I will describe extensions of the $R+R^2$ model with a recently identified type of curvature corrections that keep the cosmological equations second-order and which therefore give rise to a well-behaved cosmological evolution. We use holographic methods to constrain the couplings of the new operators and then we derive the predictions for the power spectrum of tensor and scalar primordial fluctuations. The predicted values of the scalar spectral index and the tensor-to-scalar ratio turn out to lie within experimental constraints, but observations in the near future may be able to distinguish the presence of higher-curvature corrections.

See also

GeomR2.pdf