New Physics Results from the FASER Experiment

FASER, the ForwArd Search ExpeRiment, has successfully taken data at the LHC since the start of Run 3 in 2022. From its unique location along the beam collision axis 480 m from the ATLAS interaction point, FASER has world-leading sensitivity to many models of long-lived particles. In this talk, a brief status update of the FASER experiment will be given, followed by a summary of the results of a search for a light, long-lived particle decaying into a pair of photons. In particular, axion-like particles (ALPs) are targeted where the ALP couples to the electroweak gauge bosons. The search uses LHC Run 3 data collected at $\sqrt{s} = 13.6$ TeV corresponding to an integrated luminosity of 57.7 fb$^{-1}$ to place new constraints on ALP parameter space for masses up to 300 MeV and coupling strengths as low as $g_{aWW}\sim10^{-4}$ GeV$^{-1}$. The results are also interpreted in the context of other new physics signatures with multiple photons in the final state.