Regular Article - Theoretical Physics
Higgs portal to dark matter and decays
Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1, 76131, Karlsruhe, Germany
* e-mail: email@example.com
Accepted: 14 July 2020
Published online: 24 July 2020
We consider a Higgs portal model in which the 125-GeV Higgs boson mixes with a light singlet mediator coupling to particles of a Dark Sector and study potential decays in the Belle II experiment. Multiplying the gauge-dependent off-shell Standard-Model b-s-Higgs vertex with the sine of the Higgs mixing angle does not give the correct b-s- vertex. We clarify this issue by calculating the b-s- vertex in an arbitrary gauge and demonstrate how the dependence cancels from physical decay rates involving an on-shell or off-shell . Then we revisit the phenomenology and point out that a simultaneous study of and helps to discriminate between the Higgs portal and alternative models of the Dark Sector. We further advocate for the use of the lifetime information contained in displaced-vertex data with decaying back to Standard-Model particles to better constrain the mass or to reveal additional decay modes into long-lived particles.
© The Author(s), 2020