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arXiv · 2606.27799

New interpretation of the Minkowski limit of $R^2$ gravity

Valerio Faraoni·Luca Gallerani·Alain Maltais-Gosselin·Santiago Novoa-Cattivelli·Uri Gorman
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Abstract

It is well-established that the Minkowski limit of pure $f(R)=R^2$ gravity breaks down, unlike that of full Starobinsky theory $f(R)=R+\alpha R^2$. We provide a novel interpretation of this phenomenon using the recent thermal analogy between scalar-tensor gravity and Eckart's relativistic dissipative fluids. In this framework, we show that approaching the Minkowski background corresponds to a diverging effective ``gravitational temperature''. This perspective naturally rephrases the strong coupling problem as a thermal singularity, demonstrating that $R^2$ gravity departs infinitely far from General Relativity rather than recovering it.

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Valerio Faraoni, Luca Gallerani, Alain Maltais-Gosselin, Santiago Novoa-Cattivelli, Uri Gorman. 2026-06-26. New interpretation of the Minkowski limit of $R^2$ gravity. https://arxiv.org/abs/2606.27799

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