The Projective Bundle Formula for Grothendieck-Witt spectra

Abstract

Grothendieck-Witt spectra represent higher Grothendieck-Witt groups and higher Hermitian K-theory in particular. A description of the Grothendieck-Witt spectrum of a finite dimensional projective bundle $\mathbb{P}(\mathcal{E})$ over a base scheme $X$ is given in terms of the Grothendieck-Witt spectra of the base, using the dg category of strictly perfect complexes, provided that $X$ is a scheme over $\text{Spec }\mathbb{Z}[1/2]$ and satisfies the resolution property, e.g. if $X$ has an ample family of line bundles.