  We study the entanglement entropy between the two outgoing particles in an
elastic scattering process. It is formulated within an S-matrix formalism using
the partial wave expansion of two-body states, which plays a significant role
in our computation. As a result, we obtain a novel formula that expresses the
entanglement entropy in a high energy scattering by the use of physical
observables, namely the elastic and total cross sections and a physical bound
on the impact parameter range, related to the elastic differential
cross-section.
