Light Scalars and the Koto Anomaly.

Area of Science:

• Particle Physics
• High Energy Physics
• Beyond Standard Model Physics

Background:

• The KOTO experiment searches for rare Kaon decays.
• An excess of events in K_{L}→π^{0}νν[over ¯] has been observed.
• This excess may indicate new physics phenomena.

Purpose of the Study:

• To investigate potential explanations for the KOTO excess.
• To explore the role of weakly coupled scalars in Kaon decays.
• To test specific theoretical models, namely the minimal Higgs portal and a hadrophilic scalar model.

Main Methods:

• Theoretical analysis of scalar particle interactions.
• Model building for new physics scenarios.
• Comparison of model predictions with experimental data and constraints.

Main Results:

• Weakly coupled scalars produced from Kaon decays can explain the KOTO excess.
• The minimal Higgs portal and hadrophilic scalar models are consistent with KOTO data.
• These models satisfy existing experimental limits.

Conclusions:

• The observed KOTO excess can be attributed to new physics.
• Minimal Higgs portal and hadrophilic scalar models offer compelling explanations.
• These models provide strong motivation for further investigation of the KOTO anomaly.