# Jordan frame no-hair for spherical scalar-tensor black holes

## TL;DR

This paper proves a no-hair theorem for spherical black holes in scalar-tensor gravity directly in the Jordan frame, expanding the scope of previous theorems to include non-constant Brans-Dicke couplings.

## Contribution

It provides the first proof of a no-hair theorem in the Jordan frame for spherical scalar-tensor black holes, including non-constant couplings.

## Key findings

- No-hair theorem holds in Jordan frame for spherical black holes
- The theorem applies to non-constant Brans-Dicke couplings
- Proof is limited to spherical symmetry, not axisymmetry

## Abstract

A no-hair theorem for spherical black holes in scalar-tensor gravity is presented. Contrary to the existing theorems, which are proved in the Einstein conformal frame, this proof is performed entirely in the Jordan frame. The theorem is limited to spherical symmetry (instead of axisymmetry) but holds for non-constant Brans-Dicke couplings.