Self-Variation Dynamics and Particle Masses from First Principles

We present a minimal axiomatic framework, the Self-Variation Theory (SVT), in which intrinsic particle properties undergo spacetime self-variation. Total four-momentum emerges as a conserved quantity, and particle masses are determined from the dynamically allowed values of its components. In particular, the action principle (Axiom IV) selects the physically admissible four-momentum configurations, providing a first-principles determination of the admissible total four-momentum configurations and the corresponding invariant masses. An illustrative calculation of particle masses using a spacetime distribution function Φ(x) is presented and compared with experimental values.