Spin as Proper-Time Holonomy in Causal Lorentzian Theory (CLT) Geometric Origin of Spin-½, Statistics, Antimatter, and Self- Conjugate Bosons

The origin of particle spin remains conceptually obscure in standard quantum mechanics, wherespin is introduced as an intrinsic internal degree of freedom represented by spinors, withoutgeometric or causal explanation. In this work we show that within Causal Lorentzian Theory(CLT), spin emerges naturally as a proper-time holonomy associated with closed internal causaltransport loops. The spin-½ property arises because a single 2𝜋 rotation does not return theinternal causal state to itself, while a 4𝜋 rotation does. Pauli exclusion follows fromincompatibility of non-trivial holonomy classes, particle–antiparticle conjugation corresponds toreversal of holonomy orientation, and bosons correspond to trivial internal holonomy. Photonsappear as the null, self-conjugate limit with vanishing proper time. Spin, statistics, antimatter,and self-conjugacy are thus unified as consequences of spacetime causality, without postulatingintrinsic spin, wavefunction antisymmetry, or negative-energy states.