  Pumping graphene with circularly polarized light is the archetype of
light-tailoring topological bands. Realizing the induced Floquet-Chern
insulator state and tracing clear experimental manifestions has been a
challenge, and it has become clear that scattering effects play a crucial role.
We tackle this gap between theory and experiment by employing microscopic
quantum kinetic calculations including realistic electron-electron and
electron-phonon scattering. Our theory provides a direct link to the build-up
of the Floquet-Chern insulator state in light-driven graphene and its detection
in time- and angle-resolved photoemission spectroscopy (ARPES). This allows us
to study the stability of the Floquet features due to dephasing and
thermalization effects. We also discuss the ultrafast Hall response in the
laser-heated state. Furthermore, the induced pseudospin texture and the
associated Berry curvature gives rise to momentum-dependent orbital
magnetization, which is reflected in circular dichroism in ARPES (CD-ARPES).
Combining our nonequilibrium calculations with an accurate one-step theory of
photoemission allows us to establish a direct link between the build-up of the
topological state and the dichroic pump-probe photoemission signal. The
characteristic features in CD-ARPES are further corroborated to be stable
against heating and dephasing effects. Thus, tracing circular dichroism in
time-resolve photoemission provides new insights into transient topological
properties.
