Introduction:

The aim of the FPC is to provide a phenomenological framework to the experimental searches for feebly-interacting particles. The framework is organized along three main physics topics:

1) Ultra-light FIPs (< 1 eV): this includes axion/ALP phenomenology, ultra-light Dark Matter candidates and connection to gravitational waves and astroparticle/cosmology bounds.

2) Light (MeV-GeV) dark matter: this includes searches at accelerator-based experiments, direct detection experiments, including inputs from astroparticle and cosmology;

3) Right handed neutrinos in low-scale (< EW scale) seesaw models and their connection to active neutrino physics.

The framework comprises a set of benchmarks representatives of large classes of models. The list of benchmarks is evolving following the fast theoretical progress.  The framework allows  results from different areas of research (particle physics at accelerator-based experiments, active neutrino physics, dark matter direct and indirect detection, astroparticle and cosmology, etc.) to be compared against each other and to identify still uncovered regions of parameter space.

List of current theoretical benchmarks for FIPs:

- The FPC benchmarks currently in use are based on the portal formalism, introduced in Section 2 and detailed in Section 9 of the PBC BSM Working Group report, https://arxiv.org/pdf/1901.09966.pdf.

- Evolution of these benchmarks are discussed in Section 2.6, 3.8, 4.4, 5.6 for Vector, Pseudo-scalar, Scalar and Fermion portals, respectively, of the recent FIPs 2020 Workshop Report, https://arxiv.org/pdf/2102.12143.pdf.

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