CMB Tensor Anisotropies in f(R) Gravity

The cosmic microwave background (CMB) carries information from the last scattering surface that puts constraints on the multitude of proposed cosmological models and the gravitation theories they are based on. One class of such theories is $f(R)$ gravity, which has become an interesting endeavour to correct for the degeneracies of the concordance model. We presents a description of CMB anisotropies generated by tensor perturbations in $f(R)$ theories of gravity. The temperature and the $E$-mode polarisation power spectra in the special case of $f(R)=R^n$ are computed using a modified version of CAMB package.