Higgs portal to dark matter and decays

Aliaksei Kachanovich; Ulrich Nierste; Ivan Nišandžić

doi:10.1140/epjc/s10052-020-8240-z

EPJ

Higgs portal to dark matter and $B\rightarrow K^{(*)}$ decays

Aliaksei Kachanovich, Ulrich Nierste and Ivan Nišandžić^*

Institute for Theoretical Particle Physics (TTP), Karlsruhe Institute of Technology (KIT), Wolfgang-Gaede-Straße 1, 76131, Karlsruhe, Germany

Received: 23 March 2020
Accepted: 14 July 2020
Published online: 24 July 2020

Abstract

We consider a Higgs portal model in which the 125-GeV Higgs boson mixes with a light singlet mediator $$h_2$$

coupling to particles of a Dark Sector and study potential $b\rightarrow s h_2$ 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- $$h_2$$

vertex. We clarify this issue by calculating the b-s- $$h_2$$

vertex in an arbitrary $R_\xi$ gauge and demonstrate how the $\xi$ dependence cancels from physical decay rates involving an on-shell or off-shell $$h_2$$

. Then we revisit the $b\rightarrow s h_2$ phenomenology and point out that a simultaneous study of $B\rightarrow K^* h_2$ and $B\rightarrow K h_2$ helps to discriminate between the Higgs portal and alternative models of the Dark Sector. We further advocate for the use of the $$h_2$$

lifetime information contained in displaced-vertex data with $$h_2$$

decaying back to Standard-Model particles to better constrain the $$h_2$$

mass or to reveal additional $$h_2$$

decay modes into long-lived particles.

15th European Conference on Atoms Molecules and Photons (ECAMP)
June 30 to July 4, 2025
Innsbruck, Austria

EPJ

Higgs portal to dark matter and decays

Conference announcements

Higgs portal to dark matter and $B\rightarrow K^{(*)}$ decays