Parameter matching between PN and NR via an inner-zone matching for binary black holes

In PN theory and NR simulations, source parameters are defined differently. In NR, masses and spins of each companion are measured quasi-locally from apparent-horizon geometry, whereas in PN they are attributes of point particles defined via asymptotic matching in "body zones". Although these definitions coincide in the infinite-separation limit, they differ by finite-separation corrections that matter for precision modeling. We construct a gauge and definition consistent mapping between PN and NR parameters by constructing a time-dependent diffeomorphism that matches the NR metric to a semi-analytic, perturbed black-hole description in the inner zone. In an overlapping region, we compare the multipolar content of the NR field to a corresponding perturbed black-hole model to identify source parameters, residual kinematics, and gauge freedoms. The inner-zone metric is then asymptotically matched to a PN two-body metric, bridging the map between NR and PN parameter definitions. We also discuss implications for PN–NR waveform hybridization.