TY  - JOUR
AU  - Creminelli, P.
AU  - Loayza, N.
AU  - Serra, F.
AU  - Trincherini, E.
AU  - Trombetta, L. G.
PY  - 2020
DA  - 2020//
TI  - Hairy black-holes in shift-symmetric theories
T2  - J. High Energy Phys.
JO  - Journal of High Energy Physics
SP  - 045
EP  - 24pp
VL  - 08
IS  - 8
PB  - Springer
KW  - Black Holes
KW  - Classical Theories of Gravity
AB  - Scalar hair of black holes in theories with a shift symmetry are constrained by the no-hair theorem of Hui and Nicolis, assuming spherical symmetry, time-independence of the scalar field and asymptotic flatness. The most studied counterexample is a linear coupling of the scalar with the Gauss-Bonnet invariant. However, in this case the norm of the shift-symmetry current J(2) diverges at the horizon casting doubts on whether the solution is physically sound. We show that this is not an issue since J(2) is not a scalar quantity, since J(mu) is not a diffinvariant current in the presence of Gauss-Bonnet. The same theory can be written in Horndeski form with a non-analytic function G(5)similar to log X . In this case the shift-symmetry current is diff-invariant, but contains powers of X in the denominator, so that its divergence at the horizon is again immaterial. We confirm that other hairy solutions in the presence of non-analytic Horndeski functions are pathological, featuring divergences of physical quantities as soon as one departs from time-independence and spherical symmetry. We generalise the no-hair theorem to Beyond Horndeski and DHOST theories, showing that the coupling with Gauss-Bonnet is necessary to have hair.
SN  - 1029-8479
UR  - https://arxiv.org/abs/2004.02893
UR  - https://doi.org/10.1007/JHEP08(2020)045
DO  - 10.1007/JHEP08(2020)045
LA  - English
N1  - WOS:000562728200001
ID  - Creminelli_etal2020
ER  -