Carroll-Weyl gauged null strings in AdS

Abstract

We study the Carroll-Weyl gauged null string in the Poincaré patch of ${\mathrm{AdS}}_D$ and its BRST quantization. In Poincaré coordinates $X^A=(z,x^i)$, the radial conformal Killing vector $K={\partial }_z$ becomes homothetic in a suitable conformally related frame. A field-dependent rescaling of the homothetic Hamiltonian constraint then leads to the radial-adapted basis $\mathcal{M}=\frac{1}{2}(P_z^2+P_i{P}^i)$, $\mathcal{L}=-P_A{X}^{\prime A}$, and $\mathcal{S}=P_z$, with $\mathcal{M}$ invariant along the Carroll-Weyl radial flow. Their modes form a ${\mathrm{BMS}}_3$ algebra extended by an abelian weight-one current. We classify the central extensions allowed by this residual algebra and find four independent cohomology classes in the $LL$, $LM$, $LS$, and $SS$ channels. We then construct the associated BRST complex, including the ghost pair for the radial Carroll-Weyl constraint. In the canonical highest-weight first-order representation, only the Virasoro-type central extension is realized: $(c_{LL},c_{LM},c_{LS},c_{SS})=(2D-54,0,0,0)$. Cancellation of the corresponding nontrivial BRST cocycle therefore gives $D=27$ in this representation. This differs structurally from the minimal flat Carroll-Weyl theory, where the dilation constraint $X\cdot P$ gives extra anomaly channels.

arXiv comment35+21 pages, 3 figures