Paper D1 — Mathematical Formulation of the Neutrino

This paper formulates, within the framework of effective field theory (EFT), the mathematical compatibility of mass minimality approaching zero and non-vanishing phase communication in a low-gradient phase vortex system based on the Koma density field. By decomposing Fisher information into spatial and phase components, it is shown that phase structure is preserved even in the limit where spatial gradients vanish. Neutrinos are thereby redefined as a spatially minimal and phase-nonzero structure. This paper is confined to the C-layer (syntactic layer); interpretive and philosophical dimensions are addressed in Paper D-2. Keywords: neutrino, low-gradient phase vortex, Fisher information, effective field theory, Koma Theory, information-arrangement density. Note on Mathematical Formalization This paper is presented as a structural hypothesis. Mathematical formalization and rigorous proof are intentionally left open, and external verification is welcomed.