Metastrings, Metaparticles and Black Hole Thermodynamics: On the Road Towards a Non-singular Black Hole Remnant

TL;DR

This paper explores how metastring theory and metaparticles modify black hole thermodynamics, leading to a non-singular, stable remnant with finite temperature and phase transition features, by incorporating quantum corrections and correlations in entropy.

Contribution

It introduces a novel approach to black hole thermodynamics using metastring theory, resolving singularities and predicting stable remnants through entangled entropy and modular spacetime effects.

Findings

Black hole temperature is finite and maximal.

Heat capacity diverges indicating a phase transition.

Hawking radiation halts, leaving a stable remnant.

Abstract

We investigate the thermodynamic evolution and endpoint of black hole evaporation in the framework of metastring theory and its particle excitations, the metaparticles. Metaparticles arise as zero modes of metastrings propagating on modular (doubled) spacetime and obey a modified dispersion relation exhibiting intrinsic UV/IR mixing controlled by a duality scale mu. Using a generalized Bekenstein argument adapted to metaparticles, we derive quantum-corrected entropy contributions associated with geometric and dual (winding-like) sectors of the underlying phase space. When treated independently, these two entropy branches lead to an incomplete thermodynamic description, exhibiting unphysical behavior at small horizon area. We show that consistently treating the metaparticle as a single entangled quantum object -- rather than as two independent sectors -- naturally resolves these pathologies. We propose a pseudo-entangled total entropy that incorporates correlations between the geometric and dual sectors. The reality requirement of the entropy dynamically enforces a minimal horizon area and, equivalently, a minimal effective length scale associated with modular spacetime. The resulting black hole thermodynamics exhibits a finite maximal temperature, a divergence of the heat capacity signaling a continuous phase transition, and a shutdown of Hawking radiation through geometric channels, leaving behind a cold, stable remnant. Unlike matter-supported or curvature-bounded regular black holes, the remnant obtained here is non-material and non-geometric in nature, corresponding to a finite modular core of spacetime rather than a dust-filled interior. We compare this scenario with mimetic gravity and other non-singular black hole models, emphasizing the distinct role played by first-class constraints, entropy, and modular geometry in the present framework.