Quadratic Riemann-Roch formulas

Abstract: In this article, we produce Grothendieck-Riemann-Roch formulas for cohomology theories that are not oriented in the classical sense. We then specialize to the case of cohomology theories that admit a so-called symplectic orientation and show how to compute the relevant Todd classes in that situation. At the end of the article, we illustrate our methods on the Borel character linking Hermitian K-theory and rational MW-motivic cohomology.