2026/06/24(Wed) 11:00 -12:30 五樓第一會議室 5F, 1st Meeting Room
Title
Discriminating the Dark Matter Spin at a Muon Collider via the Higgs Portal
Speaker
Dr. Jinheung Kim (Korea Institute for Advanced Study, South Korea)Abstract
Dark matter (DM) remains one of the central puzzles in particle physics, and the minimal Higgs portal is among the most widely studied frameworks for it: simple, yet flexible enough to accommodate DM candidates of various spins. While such minimal models are tightly constrained by the observed relic abundance and direct detection, these constraints can be relaxed or even evaded once the dark sector has a richer structure. In that case only a subset of the dark-sector states shows up at colliders, so the collider phenomenology is well approximated by the minimal Higgs portal, and discriminating the DM spin becomes a direct window into the structure of the hidden sector.
In this talk, I will explore the spin-discrimination potential of the Higgs portal at a multi-TeV muon collider (MuC). There, DM is produced through off-shell Higgs bosons in vector boson fusion, with the invariant mass of the DM pair as the key observable: the off-shell Higgs width scales linearly in this invariant mass for fermion DM (FDM) but cubically for vector DM (VDM), imprinting distinct recoil-mass distributions. I will describe how a single neural network, trained on a signal sample uniform in recoil mass, can suppress the SM background across all benchmarks and both scenarios, and how a binned log-likelihood-ratio test exploits the spectral shape to map out the reach. Putting these together, I will show that the MuC can not only discover Higgs portal DM over a broad range of mixing angles and mediator masses, but also discriminate the fermion and vector scenarios across a sizable region of parameter space, turning the DM spin into a concrete experimental target and, through it, a probe of the underlying dark sector.
Language
演講語言 (Language): in English