Interaction between gravitational waves and domain walls - art. no. 024011

We study the gravitational perturbations of thick domain walls. The refract ion index and spin properties of the solutions interior to the wall are ana lyzed in detail. It is shown that the gravitational waves suffer a refracti on process by domain walls. The reflection and transmission coefficients ar e derived in the thin wall limit. In relation to the spin content, it is sh own that the "X" helicity 2 gravitational wave mode maintains in the domain wall the same polarization state as in vacuum. On the contrary, the "+" mo de, of pure helicity 2 in vacuum, is contaminated inside the wall with a sp in 0 state, as well as with spin 2, helicity 0 and 1 states.