Do Higgs bosons decay into beyond-Standard-Model particles?

Determine whether the Higgs boson decays into particles not included in the Standard Model, and, if such decays occur, identify the non-Standard-Model final states responsible for these decays to clarify potential connections to dark-sector phenomena.

Background

In motivating a future collider program, the authors emphasize gaps in current knowledge about Higgs interactions, especially rare or unconventional decay modes. They note that precision measurements and high-statistics Higgs samples could reveal decays to particles outside the Standard Model, which might illuminate dark matter or other hidden-sector physics.

A tau lepton collider is proposed partly because heavier lepton beams could enhance Higgs production channels and enable sensitive searches for such non-Standard-Model decays.