The Forward Physics Facility at the High-Luminosity LHC

Abstract

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF’s physics potential.

Probing right-handed neutrinos dipole operators

“…FACET [61], FASER 2 [62,63], MAPP [64,65] and SHiP [66,67]. In addition, we will also discuss constraints from cosmology and astrophysics.…”

“…In this section we study the prospects for detection of long-lived RH neutrinos at the proposed future experiments SHiP [66] and FASER 2 [62,63]. These experimental facilities have the capability to probe long-lived particles in a variety of hidden sector models [63,93].…”

“…The FASER collaboration has proposed to build a suite of forward detectors to be placed within the LHC environment along the beam axis, nearby the ATLAS experiment [63]. These experiments are dedicated to study several interesting topics, as the properties of neutrinos, QCD in the forward regime and new physics beyond the SM, including dark sectors.…”

Searching for a single photon from lightest neutralino decays in R-parity-violating supersymmetry at FASER

“…Long-lived particles (LLPs) have in recent years received increased attention [40][41][42][43][44][45]. LLPs are predicted in a wide range of BSM models such as split SUSY, RPV-SUSY, a class of portal-physics models [axion-like particles (ALPs), heavy neutral leptons, a dark Higgs scalar, dark photons], and models of neutral naturalness -which are often related to the non-vanishing neutrino masses or dark matter.…”

Anomalous and axial Z′ contributions to g−2

“…It is also worth mentioning that studying anomalous U(1)s is very timely due to upcoming experiments. The Forward Physics Facility (FPF) is planned to operate near the ATLAS interaction point during the LHC high-luminosity era [135]. It will investigate long-lived particles that might escape the apparatus, and new abelian gauge fields have a prominent position in these searches.…”