Model-Independent Bound on Neutrino Energy Reconstruction from Nuclear Targets

Neutrino energy reconstruction on nuclear targets underlies oscillation measurements and precision tests of weak interactions. Inclusive charged–current data have long exhibited degeneracies commonly attributed to axial-mass tuning, multinucleon dynamics, and final-state interactions. This work shows that, even in the idealized limit of perfect detectors and exact nuclear dynamics, inclusive lepton-only reconstruction admits no unique inverse. A strictly positive lower bound on neutrino energy resolution follows from the finite energy-transfer support of the inclusive nuclear axial response. The result identifies an irreducible contribution to reconstruction uncertainty that is independent of modeling assumptions and experimental resolution.