Principal 3-Bundles with Adjusted Connections
Gianni Gagliardo, Christian Saemann, Roberto Tellez-Dominguez
TL;DR
We develop a framework for adjusted connections on principal $3$-bundles by deriving explicit adjustment data for $3$-term $L_infty$-algebras and formulating a local BRST description. The paper then introduces adjusted $2$-crossed modules of Lie groups and provides a complete global description of principal $3$-bundles with adjusted connections through differential cocycles, including the necessary cocycle, coboundary, and higher coboundary relations and their adjustment conditions. Applications span tensor hierarchies in $d=4$ gauged supergravity, twisted differential string structures, and categorified tori that may uplift T-duality to M-theory via $U$-duality, with the categorified torus serving as a potential tool for lifting dualities in higher dimensions. The central result is that adjusted data, encoded in maps $\kappa_{1,2,3,4}$, yield deformed curvatures $F,H,G$ with modified Bianchi identities and globular/gluing relations, providing a differential refinement of higher gauge theory for principal $3$-bundles.
Abstract
We explore the notion of adjusted connection for principal 3-bundles. We first derive the explicit form of an adjustment datum for 3-term $L_\infty$-algebras, which allows us to give a local description of such adjusted connections and their infinitesimal symmetries. We then introduce the notion of an adjusted 2-crossed module of Lie groups and provide the explicit global description of principal 3-bundles with adjusted connections in terms of differential cocycles. These connections appear in a number of context within high-energy physics, and we list local examples arising in gauged supergravity and a global example arising in various contexts in string/M-theory. Our primary motivation, however, stems from U-duality, and we define a notion of categorified torus that forms an adjusted 2-crossed module, which we hope to be useful in lifting T-duality to M-theory.
