Parametrised modified gravity and the CMB Bispectrum
  We forecast the constraints on modified theories of gravity from the cosmic microwave background (CMB) anisotropies bispectrum that arises from correlations between lensing and the Integrated Sachs-Wolfe effect. In models of modified gravity the evolution of the metric potentials is generally altered and the contribution to the CMB bispectrum signal can differ significantly from the one expected in the standard cosmological model.We adopt a parametrised approach and focus on three different classes of models: Linder's growth index, Chameleon-type models and f(R) theories. We show that the constraints on the parameters of the models will significantly improve with future CMB bispectrum measurements. 
Eleonora Di Valentino, Alessandro Melchiorri, Valentina Salvatelli,   Alessandra Silvestri
astro-ph.CO gr-qc hep-ph