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arXiv · 2509.17648

Emergent Composite Particles from the Universal Exact Identities in Quantum Many-Body Systems with Generic Bilinear Interactions

Hui Li
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Abstract

A fundamental challenge in quantum many-body physics is to understand the universal properties of strongly correlated systems. In this work, we establish a universal and exact identity from the Dyson-Schwinger equations within the Keldysh-Schwinger field theory for systems with generic bilinear interactions. Our derivation demonstrates the emergence of composite particles as "elementary excitations", whose Green's functions definitively determine the original single-particle Green's function. This universal relation uniquely identifies the composite particles governing correlations and rigorously connects their spectra to the observable single-particle spectrum. Thus, our exact identity reveals a new pathway toward a paradigm for understanding many-body correlated systems.

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Hui Li. 2025-09-22. Emergent Composite Particles from the Universal Exact Identities in Quantum Many-Body Systems with Generic Bilinear Interactions. https://arxiv.org/abs/2509.17648

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