Final state interaction effect in pure annihilation Bs → ρρ decay

We analyzed the process of B-s -> rho rho decay in quantum chromodynamics factorization (QCDF) and final state interaction (FSI) effects. In QCDF, for this decay, we have only the annihilation graph and we expected a small branching ratio. Then we considered the FSI effect as a sizable correction where the intermediate states are pi(0)pi(0), pi(+)pi(-), K-0(K) over bar (0), andK(+)K(-) mesons. To consider the amplitudes of these intermediate states, the QCDF approach was used. The experimental branching ratio of B-s -> rho rho is less than 3.20 x 10(-4) and our result is 1.08 x 10(-9) and 3.29 x 10(-4) from QCDF and FSI, respectively.