T. Johnson-Freyd

activity

20102026

most citedOn the classification of topological orders

177 citations · 633 across the 31 of their papers we have counts for

collaborators

Showing 2017Show all

3 papers · 1 filter

hep-th2017★ 112 cited

Symmetry Protected Topological phases and Generalized Cohomology

Davide Gaiotto, Theo Johnson-Freyd

We discuss the classification of SPT phases in condensed matter systems. We review Kitaev's argument that SPT phases are classified by a generalized cohomology theory, valued in th…

math.QA2017★ 23 cited

The Moonshine Anomaly

Theo Johnson-Freyd

The anomaly for the Monster group $M$ acting on its natural (aka moonshine) representation $V^{♮}$ is a particular cohomology class $ω^\natural \in \mathrm{H}^3(\math…

math.GR2017★ 9 cited

$H^{4} (Co_{0}; Z) = Z /24$

Theo Johnson-Freyd, David Treumann

We show that the fourth integral cohomology of Conway's group $Co_{0}$ is a cyclic group of order $24$ , generated by the first fractional Pontryagin class of the $24$ -dimens…

Symmetry Protected Topological phases and Generalized Cohomology

The Moonshine Anomaly

H4(Co0​;Z)=Z/24

$H^{4} (Co_{0}; Z) = Z /24$