2025/07/02 by Reuven Balkin, Balkin, Reuven, Stefania Gori +3 · 1 citation
Physics and Astronomy · Computer Science · #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Computational Physics and Python Applications
paper · pdf · doi:10.48550/arxiv.2507.01947
We analyze the three-body decays of the long-lived neutral kaon KL → ππa, where a is an axion-like particle (ALP), and compare them to the two-body decay KL → π0 a. While the latter requires both flavor violation (FV) and CP violation (CPV), the former can proceed via FV alone, allowing the ratio of decay rates to serve as a probe of CPV of the underlying UV theory. We emphasize the importance of weak-interaction-induced contributions, often neglected in recent calculations. We explore both minimal and non-minimal flavor-violating scenarios, and identify classes of models where ALP production from neutral three-body decays is comparable to - or even dominates over - the two-body decay, despite its reduced phase space. Finally, we discuss the phenomenological implications of our results and show how these decays can provide complementary probes of ALP couplings beyond those accessible via charged kaon channels.