Gravitational Waves in f(R) Gravity

We investigate the imprint of the tensor perturbation on the angular power spectra of the cosmic microwave background in the f(R) gravity. Comparing with the scalar perturbation, we find that the tensor perturbation in the f(R) gravity has little impact on the temperature angular power spectra. There is also little impact of the tensor perturbation in the f(R) gravity on the E and B types of angular power spectra.