paper

Extended black hole thermodynamics in a DGP braneworld

arXiv:2508.18508 · doi:10.1007/s10714-026-03525-2

Abstract

We develop extended black-hole thermodynamics on a Dvali--Gabadadze--Porrati (DGP) brane by promoting the brane tension to a thermodynamic variable within the extended Iyer--Wald framework. The brane tension acts as a localized vacuum energy with pressure , yielding a new work term in the first law and the corresponding Smarr relation. For static, spherically symmetric black holes we show that the conjugate volume equals the geometric volume ; for stationary, axisymmetric solutions it admits a covariant, slice-independent definition and evaluates to . Working on the ghost-free normal branch, the brane is asymptotically flat with a single horizon, so the construction avoids de Sitter obstructions. Along a flat-brane path, asymptotic flatness is preserved by co-varying the bulk cosmological constant, and induced-gravity effects are suppressed by . These results establish a consistent flat-braneworld realization of black-hole chemistry in which brane tension provides the physically motivated pressure variable.

9 pages, no figures. Accepted for publication in General Relativity and Gravitation

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