An effective cosmological constant as black hole primary hair

TL;DR

This paper explores generalized Proca theories, revealing that black holes can have primary hair with a naturally arising cosmological constant, expanding understanding of black hole solutions without explicit cosmological terms.

Contribution

It introduces a broader solution space in generalized Proca theories allowing black holes with primary hair and a naturally emergent cosmological constant without explicit cosmological terms.

Findings

Black hole solutions with primary hair identified.

Cosmological constant emerges as an integration constant.

Broader solution space due to relaxed regularization constraints.

Abstract

We study Generalized Proca theories inspired by the recent regularised Proca theory of four-dimensional Gauss-Bonnet gravity. By abandoning the rigid constraints typically imposed by specific regularization schemes, we treat the coefficients of the terms in the action as free parameters. This approach uncovers a broader solution space that admits static and spherically symmetric black hole solutions characterized by primary hair, where, surprisingly, the cosmological constant arises naturally as a constant of integration even in the absence of a bare cosmological term.