Scattering equations and string theory amplitudes

Scattering equations for tree-level amplitudes are viewed in the context of string theory. To this end we are led to define a new dual model whose amplitudes coincide with string theory in both the small and large alpha' limit, computed algebraically on the surface of solutions to the scattering equations. Because it has support only on the scattering equations, it can be solved exactly, yielding a simple resummed model for alpha' corrections to all orders. We use the same idea to generalize scattering equations to amplitudes with fermions and any mixture of scalars, gluons, and fermions. In all cases checked we find exact agreement with known results.