Notes on exact solvability for rotating and pulsating strings in nonrelativistic Lifshitz background

Abstract: We construct one dimensional exactly solvable model by choosing a probe fundamental string rotating and pulsating in the planar Lifshitz spacetime that follows nonrelativistic Lifshitz scaling. We present suitable sets of embedding coordinates for rotating and pulsating strings to embed the string worldsheet on a hyperboloid with anisotropy-dependent eccentricity. The resulting worldsheet Lagrangians straightforwardly reduce to the Lagrangian of a Neumann-Rosochatius integrable model. Although the model assumes exact solutions for both the chosen ansatz its classical Liouville integrability is found to be conditional due to the presence of finite anisotropy in the target space geometry. We further use the exact solutions of the model to yield energy-momentum dispersion relations. We interpret those from the perspective of highly degenerate frustrated $J_1-J_2$ spin chain for rotating string and frustration-free Motzkin spin chain for pulsating string.