Is Dark Matter the origin of the $B\to K \nu\bar\nu$ excess at Belle~II?

• DOI: 10.48550/arxiv.2502.04900
• Publication Date: 2025-02-07
• Authors: Lorenzo Calibbi; Tong Li; Lopamudra Mukherjee; Michael A. Schmidt
• Keywords: Bar (unit)

We present two models of dark matter~(DM) that can provide a natural explanation the excess \mbox{$B^+\to K^+ +\,\text{invisible}$} events with respect to Standard Model~(SM) prediction for \nu\bar\nu$}, which has been reported by Belle~II collaboration. Interactions between and visible sector are mediated an axion-like particle (ALP) in one case, kinetic mixing photon SM second case. Both encompass light fermion singlet as DM candidate account observed relic abundance through, respectively, freeze-in freeze-out production mechanism, while simultaneously explaining excess.