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DOE OSTI · 2447635

Calculating the two-photon exchange contribution to K L → μ + μ − decay

Chao, En-Hung (ORCID:0000000152899693)·Christ, Norman (ORCID:0000000338569641)
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Abstract

We present a theoretical framework within which both the real and imaginary parts of the complex, two-photon exchange amplitude contributing to K L → μ + μ − decay can be calculated using lattice quantum chromodynamics. The real part of this two-photon amplitude is of approximately the same size as that coming from a second-order weak strangeness-changing neutral-current process. Thus a test of the standard model prediction for this second-order weak process depends on an accurate result of this two-photon amplitude. A limiting factor of our proposed method comes from low-energy three-particle π π γ states. The contribution from these states will be significantly distorted by the finite volume of our calculation—a distortion for which there is no available correction. However, a simple estimate of the contribution of these three-particle states suggests their contribution to be at most a few percent allowing their neglect in a lattice calculation with a 10% target accuracy. Published by the American Physical Society 2024

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Chao, En-Hung (ORCID:0000000152899693), Christ, Norman (ORCID:0000000338569641). 2024-09-23. Calculating the two-photon exchange contribution to K L → μ + μ − decay. https://doi.org/10.1103/physrevd.110.054514

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