Singular cohomology from supersymmetric field theories

Abstract

We show that Sullivan's model of rational differential forms on a simplicial set $X$ may be interpreted as a (kind of) $0|1$-dimensional supersymmetric quantum field theory over $X$, and, as a consequence, concordance classes of such theories represent the rational cohomology of $X$. We introduce the notion of superalgebraic cartesian sets, a concept of space which should roughly be thought of as a blend of simplicial sets and generalized supermanifolds, but valid over an arbitrary base ring. Every simplicial set gives rise to a superalgebraic cartesian set and so we can formulate the notion of $0|1$-dimensional supersymmetric quantum field theory over $X$, entirely within the language of such spaces. We explore several variations in the kind of field theory and discuss their cohomological interpretations. Finally, utilizing a theorem of Cartan-Miller, we describe a variant of our theory which is valid over any ring $S$ and allows one to recover the $S$-cohomology $H^*(X;S)$ additively and with multiples of the cup product structure.