First results from FASER at the LHC

The ForwArd Search ExpeRiment (FASER) is a new experiment at the Large Hadron Collider (LHC) designed to search for light, weakly-interacting particles. Placed 480 m downstream from the ATLAS interaction point along the beam collision axis, FASER detects particles that travel hundreds of meters. This paper presents the first physics results from FASER using data collected during LHC Run 3 in 2022-2023. We report on searches for dark photons decaying into electron-positron pairs and axion-like particles (ALPs) decaying into photon pairs, both of which can provide insights into physics beyond the Standard Model. We discuss the first direct observation of collider neutrinos with FASER and measurements of electron neutrino and muon neutrino interaction cross-sections in the unexplored TeV energy range using the FASERν emulsion detector. These results provide new opportunities for exploring both Standard Model and Beyond the Standard Model physics in the forward region of LHC proton-proton collisions. We also discuss future prospects, including an upgrade of a preshower calorimeter detector and plans for the Forward Physics Facility in the High-Luminosity LHC era.