Strings in bimetric spacetimes

• Main Author: Ziqi Yan
• Format: Article
• Language: English
• Published: SpringerOpen 2021-09-01
• Series: Journal of High Energy Physics
• Subjects: Bosonic Strings; Renormalization Group; Sigma Models; p-branes
• Online Access: https://doi.org/10.1007/JHEP09(2021)164

Abstract We put forward a two-dimensional nonlinear sigma model that couples (bosonic) matter fields to topological Hořava gravity on a nonrelativistic worldsheet. In the target space, this sigma model describes classical strings propagating in a curved spacetime background, whose geometry is described by two distinct metric fields. We evaluate the renormalization group flows of this sigma model on a flat worldsheet and derive a set of beta-functionals for the bimetric fields. Imposing worldsheet Weyl invariance at the quantum level, we uncover a set of gravitational field equations that dictate the dynamics of the bimetric fields in the target space, where a unique massless spin-two excitation emerges. When the bimetric fields become identical, the sigma model gains an emergent Lorentz symmetry. In this single metric limit, the beta-functionals of the bimetric fields reduce to the Ricci flow equation that arises in bosonic string theory, and the bimetric gravitational field equations give rise to Einstein’s gravity.