Search for new physics on the FASER experiment at the LHC

The Forward Search Experiment (FASER) is a ground-breaking CERN-based initiative that commenced data-taking during the Summer of 2022 as part of Run 3 of the Large Hadron Collider (LHC). Positioned 480 meters downstream of the proton-proton interaction point used by the ATLAS experiment, FASER is specifically designed for the exploration of light and weakly-interacting Beyond Standard Model (BSM) particles characterized by a substantial lifetime, known as Long-Lived Particles (LLPs). FASER's instrumental configuration comprises a cylindrical spectrometer equipped with a tracker and calorimeter, submerged in a 0.6 Tesla magnetic field. This novel experiment has already accumulated approximately 40/fb of data and is anticipated to amass more than 200/fb by the end of Run 3 in 2025.

The primary focus of this research is to analyse the data obtained by FASER, concentrating on the quest for Long-Lived Dark Photons. These particles exhibit a distinctive signature characterised by two oppositely charged, high-energy tracks, originating from a common vertex within the detector. These tracks possess a combined momentum pointing back through 10 meters of concrete and 90 meters of rock to the ATLAS interaction point. Initial data analysis utilizing basic techniques will have already been conducted, with preliminary results made available. The project will involve enhancing these preliminary analyses to increase the sensitivity to dark photons and to explore other novel physics models, including axion-like particles.

Advanced multivariate techniques, such as neural networks, will be employed to develop sophisticated analyses aimed at optimizing signal selection and background reduction. This includes the integration of information from individual detector components to establish a comprehensive particle identification framework, significantly enhancing the separation of signal and background events.

Furthermore, feasibility studies will be conducted for a proposed FASER experiment upgrade, which involves the installation of an entirely new detector in a state-of-the-art facility. This upgraded FASER experiment will collect a substantially larger dataset at the High-Luminosity LHC, opening new avenues for ground-breaking discoveries in the realm of particle physics.