BSM and SM signals and backgrounds in Far-Forward Experiments at the LHC

Abstract

Two far-forward experimental systems are currently taking data during Run 3 at the Large Hadron Collider (LHC): FASER + FASER$\nu$ and SND@LHC. They are sensitive to some classes of beyond-the-Standard Model (BSM) particles, muons and neutrinos produced in the ATLAS interaction point (IP) and propagating for several hundred meters along the tangent to the accelerator beamline, up to the caverns where they are respectively located, in opposite directions with respect to the IP. Proposals are being prepared to extend these experiments to bigger ones during the HL-LHC phase. Building a Forward Physics Facility (FPF) capable of hosting a number of far-forward experiments characterized by different detection techniques, kinematical acceptance and purpose, is a possibility also under discussion. In this contribution I discuss some of the BSM and SM signals and backgrounds at the FPF, mainly focusing on QCD-related aspects.