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arXiv · 2502.04900

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

Lorenzo Calibbi·Tong Li·Lopamudra Mukherjee·Michael A. Schmidt
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Abstract

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

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Lorenzo Calibbi, Tong Li, Lopamudra Mukherjee, Michael A. Schmidt. 2025-02-07. Is Dark Matter the origin of the $B\to K \nu\bar\nu$ excess at Belle II?. https://arxiv.org/abs/2502.04900

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