HECA

New physics has traditionally been expected in the high-pT region at high-energy collider experiments. If new particles are light and weakly-coupled, however, this focus may be misguided: light particles are typically highly concentrated within a few mrad of the beam line. This opens up a novel direction in the LHC searches focusing on sub-GeV new particles and neutrino physics, which will be initiated by the FASER experiment during Run 3.

Astrophysical and cosmological observations from galactic to cosmological scales indicate the existence of dark matter. Nevertheless, most of its property still remain to be unknown and hence candidates range from 10^-31 to 10^50 GeV in its mass scale. Among them, the traditional dark matter candidate, so called WIMP (weakly interacting massive particle) is still attractive because its production mechanism, i.e., thermal freeze-out, naturally explains its abundance and pins down its mass scale to be 1 ~ 10^5 GeV.