Dark matter emission at Belle II and NA62 in the minimal flavor violation framework

Minimal flavor violation (MFV) provides a compelling framework for exploring physics beyond the Standard Model, in which new QCD-singlet fields transforming under the global <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>SU</a:mi> <a:mo stretchy="false">(</a:mo> <a:mn>3</a:mn> <a:msup> <a:mo stretchy="false">)</a:mo> <a:mn>3</a:mn> </a:msup> </a:math> quark flavor symmetry can naturally be stable and act as dark matter (DM) candidates. We show that the DM–MFV framework naturally accommodates the excess in either <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msup> <e:mi>K</e:mi> <e:mo>+</e:mo> </e:msup> <e:mo stretchy="false">→</e:mo> <e:msup> <e:mi>π</e:mi> <e:mo>+</e:mo> </e:msup> <e:mi>ν</e:mi> <e:mover accent="true"> <e:mi>ν</e:mi> <e:mo stretchy="false">¯</e:mo> </e:mover> </e:math> or <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:msup> <j:mi>B</j:mi> <j:mo>+</j:mo> </j:msup> <j:mo stretchy="false">→</j:mo> <j:msup> <j:mi>K</j:mi> <j:mo>+</j:mo> </j:msup> <j:mi>ν</j:mi> <j:mover accent="true"> <j:mi>ν</j:mi> <j:mo stretchy="false">¯</j:mo> </j:mover> </j:math> , while a unified explanation of both channels simultaneously cannot be achieved within a minimal setup containing only a single dark matter multiplet with nearly degenerate masses. Overall, our findings underscore the intricate interplay between MFV-based model building, flavored dark matter scenarios, and precision flavor experiments, highlighting flavored dark matter as a framework that is both theoretically robust and experimentally testable.