Nonunitary Classically Stable HD Gravity

TL;DR

This paper proposes a nonunitary, classically stable higher-derivative gravity model that incorporates hidden degrees of freedom, aligning thermodynamic and black hole entropies with quantum von Neumann entropy, and matches Hawking temperature.

Contribution

It introduces a nonunitary, classically stable higher-derivative gravity framework with hidden degrees of freedom that replicate matter, unifying thermodynamic and black hole entropy with quantum entropy.

Findings

Classical instability is resolved at the cost of unitarity.

Thermodynamic and black hole entropies are identified with von Neumann entropy.

The model aligns with Bekenstein-Hawking entropy and Hawking temperature.

Abstract

Classical instability in fourth order gravity is cured at the expense of unitarity. The appearance of hidden degrees of freedom replicating those of ordinary matter allows for ordinary thermodynamic entropy and black hole entropy to be identified with von Neumann entropy. The emergent picture gives a substantial agreement with B-H entropy and Hawking temperature.