Propagating Degrees of Freedom in f(R)‎ Gravity

Abstract EN

We have computed the number of polarization modes of gravitational waves propagating in the Minkowski background in f(R) gravity.

These are three of two from transverse-traceless tensor modes and one from a massive trace mode, which confirms the results found in the literature.

There is no massless breathing mode and the massive trace mode corresponds to the Ricci scalar.

A newly defined metric tensor in f(R) gravity satisfies the transverse-traceless (TT) condition as well as the TT wave equation.