Comments on the CKN Bound

TL;DR

This paper discusses the Cohen-Kaplan-Nelson (CKN) bound, interpreting it as a scale-dependent depletion of quantum field theory states, with implications for laboratory experiments and cosmological horizons.

Contribution

It offers a new interpretation of the CKN bound as a depletion of QFT states and explores its implications across different scales, including laboratory and cosmological contexts.

Findings

CKN bound causes small corrections in quantum field theory, estimated at order m_e/M_p for electron g-2.

Proposes modifications to the CKN bound due to cosmological horizons.

Connects the bound with entropy bounds and black hole physics.

Abstract

Cohen, Kaplan, and Nelson (CKN) conjectured that the UV and IR cutoffs of effective quantum field theories coupled to gravity are not independent, but are connected by the physics of black holes. We interpret the CKN bound as a scale-dependent depletion of the QFT density of states and discuss various aspects of the bound on small and large scales. For laboratory experiments, we argue that the bound provides small corrections to ordinary quantum field theory, which we estimate to be of order $m_e/M_p$ for $g-2$ of the electron. On large scales, we suggest a modification of the CKN bound due to the presence of cosmological horizons and discuss the connection with entropy bounds.