Running Love Numbers and the Effective Field Theory of Gravity

TL;DR

This paper develops a universal method to compute how effective field theory corrections influence the tidal responses of black holes, revealing that Love numbers can vary significantly, especially for extremal black holes, with implications for dark sector detection.

Contribution

Introduces universal formulae for calculating EFT-induced Love numbers of black holes, including new results for charged and extremal cases, enhancing understanding of black hole tidal properties.

Findings

Neutral black hole Love numbers run classically for l≥3

Charged black hole Love numbers run for l≥2

Extremal black holes can have large Love numbers, up to order 1

Abstract

Massive states produce higher derivative corrections to Einstein gravity in the infrared, which are encoded into operators of the Effective Field Theory (EFT) of gravity. These EFT operators modify the geometry and affect the tidal properties of black holes, either neutral or charged. A thorough analysis of the perturbative tidal deformation problem leads us to introduce a tidal Green function, which we use to derive two universal formulae that efficiently provide the constant and running Love numbers induced by the EFT. We apply these formulae to determine the tidal response of EFT-corrected non-spinning black holes induced by vector and tensor fields, reproducing existing results where available and deriving new ones. We find that neutral black hole Love numbers run classically for $l\geq 3$ while charged ones run for $l\geq2$. Insights from the Frobenius method and from EFT principles confirm that the Love number renormalization flow is a well-defined physical effect. We find that extremal black holes can have Love numbers much larger than neutral ones, up to ${\cal O}(1)$ within the EFT validity regime, and that the EFT cutoff corresponds to the exponential suppression of the Schwinger effect. We discuss the possibility of probing an Abelian dark sector through gravitational waves, considering a scenario in which dark-charged extremal black holes exist in the present-day Universe.