T-duality and T-folds for point particles

We argue that the T-duality phenomenon is not exclusively a stringy effect but it is relevant also in the context of the standard point particle dynamics. To illustrate the point, we construct a four-parametric family of four-dimensional electro-gravitational backgrounds such that the dynamics of a charged point particle in those backgrounds is insensitive to a particular permutation of the parameters although this very permutation does alter the background geometry. In particular, we find that a direct product of the Euclidean plane with the two-dimensional Euclidean black hole admits a point-particle T-dual with asymptotically negative curvature. For neutral particles, this point-particle T-duality picture gets slightly modified because the T-duality map is no longer defined everywhere but only on a dense open domain of the space of states. We suggest a possible interpretation of this phenomenon in terms of a point particle T-fold. (C) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license.

Automated summary

The T-duality phenomenon is not exclusive to string theory, but also important in standard point particle dynamics. By studying the dynamics of charged particles in different backgrounds, we find that T-duality can have different effects depending on the geometry of the background.