Title:

Some mathematical structures arising in string theory

This thesis is concerned with mathematical interpretations of some recent develop ments in string theory. All theories are considered before quantisation. The rst half of the thesis investigates a large class of Lagrangians, L, that arise in the physics literature. Noether's famous theorem says that under certain conditions there is a bijective correspondence between the symmetries of L and the \conserved currents" or integrals of motion. The space of integrals of motion form a sheaf and has a bilinear bracket operation. We show that there is a canonical sheaf d1;0 J1( ) that contains a representation of the higher Dorfman bracket. This is the rst step to de ne a Courant algebroid structure on this sheaf. We discuss the existence of this structure proving that, for a re ned de nition, we have the necessary components. The pure spinor formalism of string theory involves the addition of the algebra of pure spinors to the data of the superstring. This algebra is a Koszul algebra and, for physicists, Koszul duality is string/gauge duality. Motivated by this, we investigate the intimate relationship between a commutative Koszul algebra A and its graded Lie superalgebra Koszul dual to A, U(g) = A!. Classically, this means we obtain the algebra of syzygies AS from the cohomology of a Lie subalgebra of g. We prove H (g 2;C) ' AS again and extend it to the notion of ksyzygies, which we de ne as H (g k;C). In particular, we show that H B er(A) ' H (g 3;C), where H Ber(A) is the Berkovits cohomology of A.
