Emergent Entities in Quantum Field Theory: Particle Ontology, Extra Dimensions, and the Epistemic Limits of Fundamental Physics

This paper examines a recurring epistemological problem in fundamental physics: when does an experimentally identifiable phenomenon or a mathematically necessary structure justify an ontological claim about what fundamentally exists? Using exotic hadrons, quantum field theory, modern scattering-amplitude methods, generalized symmetries, extra dimensions, and the string landscape as case studies, it develops the central thesis that mathematical or phenomenological identifiability does not by itself entail ontological fundamentality. String theory is assessed by explicitly distinguishing its substantial mathematical and theoretical achievements from empirical confirmation and novel predictive success. Particular attention is given to underdetermination in the string landscape and to non-empirical theory assessment. The paper concludes with a deliberately limited comparison to Advaita Vedanta. This comparison is offered neither as evidence for Vedanta nor as a physical identification of Brahman with a quantum field, but as a philosophical instrument for examining the distinction between dependent manifestation and ontological ground. Version 1.1 (Minor Revision) — October 2026. Refined terminology in Section 16 equation (9), added historical QFT reference [30], and clarified the distinction between internal structure and fundamentality in Section 3.