March 2023

First Physics Results from FASER

The FASER collaboration reports the first observation of collider neutrino events. In addition, limits are set on previously unconstrained regions of dark photon parameter space.

Pre-published results for the direct observation of collider neutrino events, and preliminary results for the search for dark photons, are made available.

The above figure shows the expected (green) and observed (blue) limits on the dark photon parameter space obtained by the FASER collaboration. The mass of the hypothetical dark photon is shown along the x-axis, and its kinetic mixing strength is shown along the y-axis. Shown in grey are the existing limits from previous experiments, demonstrating that FASER is able to exlude new regions of parameter space, including some preferential for dark matter (red).