Traces for factorization homology in dimension 1

David Ayala, John Francis

Published 2021-05-03Version 1

We construct a circle-invariant trace from the factorization homology of the circle \[ {\sf trace} \colon \int^\alpha_{{\mathbb S}^1} \\underline{\sf End}(V) \longrightarrow \uno \] associated to a dualizable object $V\in {\boldsymbol{\mathfrak X}}$ in a symmetric monoidal $\infty$-category. This proves a conjecture of To\"en--Vezzosi~\cite{toen.vezzosi} on existence of circle-invariant traces. Underlying our construction is a calculation of the factorization homology over the circle of the walking adjunction in terms of the paracyclic category of Getzler--Jones~\cite{getzler.jones}: \[ \int_{{\mathbb S}^1} {\sf Adj} ~\simeq~ {\bDelta_{\circlearrowleft}}^{\triangleleft\!\triangleright} ~. \] This calculation exhibits a form of Poincar\'e duality for 1-dimensional factorization homology.