Love numbers of black p-branes: fine tuning, Love symmetries, and their geometrization

Abstract

We compute scalar static response coefficients (Love numbers) of non-dilatonic black $p$-brane solutions in higher dimensional supergravity. This calculation revels a fine-tuning behavior similar to that of higher dimensional black holes, which we explain by ``hidden'' near-zone Love symmetries. In general, these symmetries act on equations for perturbations but they are not background isometries. The Love symmetry of charged $p=0$ branes is described by the usual $SL(2,\mathbb{R})$ algebra. For $p=1$ the Love symmetry has an algebraic structure $SL(2,\mathbb{R})\times SL(2,\mathbb{R})$. The $p=0,1$ Love symmetries reduce to isometries of the near-horizon Schwarzschild-AdS${}_{p+2}$ metric in the near-extremal finite temperature limit. They further reduce to the AdS${}_{p+2}$ isometries in the extremal zero-temperature limit. We call this process geometrization. In contrast, for the $p>1$ cases, the Love symmetry is always an $SL(2,\mathbb{R})$, and there is no limit in which it becomes geometric. We interpret geometrization and its absence as a consequence of the local equivalence between the Schwarzschild-AdS${}_{p+2}$ and pure AdS${}_{p+2}$ spaces for $p=0,1$, which does not hold for $p>1$. We also show that the static Love numbers of extremal $p$-branes are always zero regardless of spacetime dimensionality, which contrasts starkly with the non-extremal case. Overall, our results suggest that the Love symmetry is hidden by nature, and it can acquire a geometric meaning only if the background has an AdS${}_2$ or AdS${}_3$ limit.

50 pages