Radiative neutron β-decay in effective field theory

We consider radiative β-decay of the neutron in heavy baryon chiral perturbation theory, with an extension including explicit Δ degrees of freedom. We compute the photon energy spectrum as well as the photon polarization; both observables are dominated by the electron bremsstrahlung contribution. Nucleon-structure effects not encoded in the weak coupling constants gA and gV are determined at next-to-leading order in the chiral expansion, and enter at the O(0.5%)-level, making a sensitive test of the Dirac structure of the weak currents possible