Effective field theory, large number of particle species, and holography

TL;DR

This paper develops an effective quantum field theory with many particle species, linking UV/IR connections to holography, and derives bounds on species number that reconcile entropy and black hole physics in cosmology.

Contribution

It introduces a framework with a large number of particle species respecting holographic bounds, connecting entropy, black holes, and cosmology in a novel way.

Findings

Entropy increases with species number near black hole collapse

Upper bound on species number aligns with holographic Bekenstein-Hawking bound

Entanglement entropy matches black hole entropy at the bound

Abstract

An effective quantum field theory (QFT) with a manifest UV/IR connection, so as to be valid for arbitrarily large volumes, can successfully be applied to the cosmological dark energy problem as well as the cosmological constant (CC) problem. Motivated by recent approaches to the hierarchy problem, we develop such a framework with a large number of particle species. When applying to systems on the brink of experiencing a sudden collapse to a black hole, we find that the entropy, unlike the total energy, now becomes an increasing function of the number of field species. An internal consistency of the theory is then used to infer the upper bound on the number of particle species, showing consistency with the holographic Bekenstein-Hawking bound. This may thus serve to fill in a large gap in entropy of any non-black hole configuration of matter and the black holes. In addition, when the bound is saturated the entanglement entropy matches the black hole entropy, thus solving the multiplicity of species problem. In a cosmological setting, the maximum allowable number of species becomes a function of cosmological time, reaching its minimal value in a low-entropy post-reheating epoch.