Determination of the pairing state in iron-based superconductors through neutron scattering

We calculate the spin susceptibility in the s(+) and s(++) superconducting states of the iron pnictides using the effective five-orbital model and considering the quasiparticle damping. For the experimentally evaluated magnitude of the quasiparticle damping and the superconducting gap, the results at the wave vector similar or equal to(pi, 0) show that the s(+/-) state is more consistent with the neutron scattering experiments, while for larger quasiparticle damping and the superconducting gap, the s(++) state can be more consistent. To distinguish between two cases that reproduce the experiments at the wave vector similar or equal to(pi, 0), we propose to investigate experimentally the wave vector similar or equal to(pi, pi).