Analysis of $B\to KM_X$ and $B\to K^* M_X$ decays in scalar- and vector-mediator dark-matter scenarios

TL;DR

This paper investigates $B$ meson decays involving missing energy, proposing that these could be explained by dark matter particles mediated by scalar or vector bosons, and offers methods to distinguish the mediator's nature.

Contribution

It introduces a framework to analyze $B$ decay widths to identify whether a scalar or vector mediator is responsible for dark matter interactions.

Findings

Decay width analysis can differentiate scalar from vector mediators.

The proposed method provides a straightforward way to identify the mediator's nature.

Dark-matter fermion pair production explains the excess in $B$ decay missing-energy events.

Abstract

The surprising excess of missing-energy events far beyond all standard-model expectations in the weak decays of the charged ground-state $B^+$ meson into some charged strange meson, rather recently observed by the Belle-II experiment, may (easily) be explained by the decay of the $B$ meson into the strange meson and a pair of dark-matter fermion and antifermion, mediated by an (intermediate) scalar or vector boson. Thorough inspections of both the total and the differential widths of these decays provide, among others, a simple means for the (straightforward) discrimination of such mediator boson's scalar or vector nature.