A Chiral $Λ$-$\mathfrak{bms}_4$ Symmetry of AdS$_4$ Gravity

Abstract: Generalising the chiral boundary conditions of $\mathbb{R}^{1,3}$ gravity for AdS$_4$ gravity, we derive chiral locally AdS$_4$ solutions in the Newman-Unti gauge consistent with a variational principle whose asymptotic symmetry algebra we show, to be an infinite-dimensional chiral extension of $\mathfrak{so}(2,3)$. This symmetry algebra coincides with the chiral $\mathfrak{bms}_4$ algebra in the flat space limit. We posit this symmetry algebra as the chiral version of recently discovered $\Lambda$-$\mathfrak{bms}_4$ algebra. We postulate line integral charges from the bulk AdS$_4$ gravity corresponding to this chiral symmetry algebra and show that the charges obey the semi-classical limit of a $\mathcal{W}$-algebra that includes a level $\kappa$ Kac-Moody $\mathfrak{sl}(2,\mathbb{R})$ current algebra. Furthermore, using the standard tools of $2d$ CFT, we derive the quantum version of this $\mathcal{W}$-algebra which may be denoted by $\mathcal{W}(2;(3/2)^2,1^3)$.