Probing Muonic Forces and Dark Matter at Kaon Factories

Understand

Rare kaon decays are excellent probes of light, new weakly-coupled particles.

• If such particles $X$ couple preferentially to muons, they can be produced in $K\to \mu \nu X$ decays.
• In this letter we evaluate the future sensitivity for this process at NA62 assuming $X$ decays either invisibly or to di-muons.
• Our main physics target is the parameter space that resolves the $(g-2)_\mu$ anomaly, where $X$ is a gauged $L_\mu-L_\tau$ vector or a muon-philic scalar.