On the cancellation of Newtonian singularities in higher-derivative gravity

Understand

Recently there has been a growing interest in quantum gravity theories with more than four derivatives, including both their quantum and classical aspects.

• In this work we extend the recent results concerning the non-singularity of the modified Newtonian potential to the most relevant case in which the propagator has complex poles.
• The model we consider is Einstein-Hilbert action augmented by curvature-squared higher-derivative terms which contain polynomials on the d'Alembert operator.
• We show that the classical potential of these theories is a real quantity and it is regular at the origin disregard the (complex or real) nature or the multiplicity of the massive poles.