Finite Mass Response to Vanishing Perturbations at Cauchy Horizons
Whether smooth transverse perturbations with vanishing L^p norm (fixed finite p≥4) can still produce a finite positive mass increment at a Cauchy horizon, in the spherically symmetric Einstein–Maxwell–scalar system with positive cosmological constant.
The proof first constructs a common nonlinear characteristic interior that exists uniformly for a whole sequence of perturbations. It works at a critical surface-gravity relation b=k/a=1-1/p. The radiation is compared with an explicit positive radial mode, and the exact mass flux is integrated to obtain an analytic law for the mass increment. The results and proofs are formalized in Lean 4.
Perturbations with vanishing L^p norm leave a finite positive mass increment that escapes every fixed time window. An explicit law gives the response's delay and duration and determines enhancement or cancellation for overlapping signed packets. Each solution has bounded mass and a local finite-energy weak extension across the horizon.
