T-duality of string charge density/bit threads correspondence in type II supergravity

Abstract: In this paper, we study Abelian T-duality of the string charge density/bit threads correspondence in ten-dimensional Type II supergravity. T-duality along the common compact circle maps the Type IIB F1-NS5-P background to a Type IIA P-NS5-F1 background with the winding and momentum charges exchanged. The radial F1 source remains an F1 source, and its projected charge density gives a bit-thread flow whose maximal flux reproduces the black hole entropy. The same duality maps D1-D5-P to D0-D4-F1. In this case, a radial D1 source becomes a D2 source wrapped on the dual circle. Contracting the resulting spatial bivector with the normalized closed one-form on that circle gives a conserved effective radial flow whose maximal flux again reproduces the entropy. Although the local metrics, dilatons, source currents, and flow norms change, the dilaton-weighted transverse area density and the integrated maximal flux are invariant. These results provide a nontrivial T-duality test of the correspondence and extend it from string currents to wrapped-brane currents that reduce to string-like flows.