Status and Plans for the NA64 Experiment

The NA64 experiment at the CERN North Area searches for dark matter production via both visible and invisible decays of sub-GeV vector mediators, such as the dark photon $A$´. In a first data taking period from 2016-2018, $A$' generation from the reaction e Z $\rightarrow$ e Z $A$' and subsequent decays $A$´ $\rightarrow x\overline{x}$ and $A$´ $\rightarrow$ e$^+$e$^-$ was studied with the help of an active dump set-up using 100 GeV/$c$ and 150 GeV/$c$ electrons. Recently, an extension of the performed searches was proposed using a 150 GeV/c muon beam, available at the M2 beamline at CERN. These measurements would allow for additional coverage of parameter space towards higher $A$' masses and would open the possibility for searches for a new gauge boson Z$_{\mu}$ that would couple predominantly to the second and third lepton generations. We will present both the analysis of the available NA64 data as well as future plans for searches with muon and electron beams that are proposed within the “Physics Beyond Colliders” framework at CERN, including optimisation of the M2 optics and integration studies for implementing NA64$\mu$ in the EHN2 experimental area.