Courant Algebroids from Categorified Symplectic Geometry: Draft Version

In categorified symplectic geometry, one studies the categorified algebraic and geometric structures that naturally arise on manifolds equipped with a closed non-degenerate n + 1-form. The case relevant to classical string theory is when n = 2 and is called ‘2-plectic geometry’. Just as the Poisson bracket makes the smooth functions on a symplectic manifold into a Lie algebra, there is a Lie 2-algebra of observables associated to any 2-plectic manifold. String theory, closed 3-forms and Lie 2-algebras also play important roles in the theory of Courant algebroids. Courant algebroids are vector bundles which simultaneously combine and generalize the structures found in tangent bundles and quadratic Lie algebras. It is known that so-called exact Courant algebroids naturally arise in string theory, and that such an algebroid is classified up to isomorphism by a closed 3-form on the base space, which then induces a Lie 2-algebra structure on the space of global sections. In this paper we begin to establish precise connections between 2-plectic manifolds and Courant algebroids. In particular, we show that any manifold M equipped with a 2-plectic form ω gives an exact Courant algebroid Eω on M with Ševera class [ω], and we construct an embedding of the Lie 2-algebra of observables into the Lie 2-algebra of sections of Eω.