Constraints on a massive double-copy and applications to massive gravity

A bstract We propose and study a BCJ double-copy of massive particles, showing that it is equivalent to KLT formula with kernel given by the inverse matrix bi-adjoint scalar amplitudes. For models uniform non-zero mass spectrum we demonstrate resulting factors on physical poles up at least 5-particle scattering, color-kinematics duality satisfying numerators always exist. scattering 5 or more procedure generically introduces spurious singularities must be cancelled imposing additional constraints. When particles are present, not enough guarantee double-copy. As an example, apply formalism Yang-Mills show 4-particle construction generates amplitudes model dRGT gravity coupled dilaton two-form parity violating couplings. in do cancel this fails generate physically sensible conjecture sufficient constraints spectrum, which addition relations, absence singularities.