Complex Mass Formalism, Superluminal Dynamics, and Multiverse Phase Transitions: A Unified Theoretical Framework

This document (v2) presents a unified theoretical framework that extends relativistic mechanics and field theories to incorporate complex mass structures, where the mass parameter is expressed as a complex quantity M=m+iμM = m + i\muM=m+iμ. It builds upon the previous works, Imaginary Mass Particles and Superluminal Motion: A Theoretical Proposal and Imaginary Mass Extensions in Relativistic Field Theories (v3), integrating these ideas into a cohesive model that predicts a unique phase transition from imaginary-mass particles to real-mass states at the critical superluminal velocity v=2cv = \sqrt{2} cv=2c. The framework introduces a complexified spacetime metric Gμν=gμν+iαμνG_{\mu\nu} = g_{\mu\nu} + i\alpha_{\mu\nu}Gμν=gμν+iαμν, modifies the Einstein-Hilbert action, and incorporates PT-symmetric structures to ensure causality and unitarity preservation. The implications of this model extend to dark matter and dark energy phenomena, cosmic inflation, ER=EPR conjectures, and multiverse phase transitions. Observational constraints (e.g., ∣μ∣≤10−22 eV/c2|\mu| \leq 10^{-22}~eV/c^2∣μ∣≤10−22 eV/c2) and experimental prospects are discussed, along with proposed future directions in theoretical and numerical research. This report is intended as a foundational contribution to ongoing studies at the intersection of high-energy physics, cosmology, and fundamental theory.