  We construct a novel event generator for the process $p \> p \to \ell^- \>
\bar{\nu}_\ell \> \ell'^+ \> \nu_{\ell'}$, which matches fixed-order
predictions at next-to-next-to-leading order in the strong coupling to a parton
shower program. The matching is achieved using the GENEVA method, in this case
exploiting a resummed calculation for the hardest jet transverse momentum at
next-to-next-to-leading logarithmic accuracy obtained via soft-collinear
effective theory and implemented in the C++ library SCETlib. This choice of
resolution variable ensures that the introduction of a jet veto, commonly used
by experimental analyses to reject multi-jet background events, does not result
in the appearance of unmitigated large logarithms for low veto scales before
showering. After validating our partonic results against publicly available
fixed order and resummed calculations, we compare our predictions to
measurements taken at the ATLAS and CMS experiments, finding good agreement.
This is the first NNLO+PS accurate event generator to use the hardest jet
transverse momentum as a resolution variable.
