Rare Kaon EFT Study

Rare kaon decays with invisible final states provide a clean probe of short-distance flavour-changing neutral currents and of possible light hidden-sector degrees of freedom. This project investigates K⁺ → π⁺ + invisible modes from the perspective of differential information rather than only total rates, using EFT/WET descriptions of s → d + invisible transitions as the starting point. The aim is to quantify how vector, scalar, tensor, sterile-neutrino, LNC/LNV, and Dirac/Majorana scenarios modify experimentally accessible spectra such as pion momentum and missing mass, and to assess how much of this information survives realistic NA62/KOTO-II-like binning.

The initial objective is exploratory: reproduce known K⁺ → π⁺ ν ν̄ spectra, map selected BSM/invisible scenarios onto differential templates, and identify whether charged and neutral kaon measurements offer complementary shape sensitivity. The intended outcome is either a compact reinterpretation framework useful for NA62/KOTO-II-style analyses, a focused charged–neutral comparison, or a documented negative result showing that existing binning and observables do not preserve enough model-discriminating information for a useful standalone study.

Page last updated on June 12, 2026