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arXiv · 2605.04137

CP asymmetries in charged meson decay to two pions

Yuval Grossman·Zoltan Ligeti·Yosef Nir
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Abstract

We study the CP asymmetries in $B^+$, $D^+$, and $K^+$ decays into $\pi^+\pi^0$. These asymmetries are commonly known to vanish in the isospin limit. We clarify what is meant by the term ``isospin limit" in this context. We provide a unified formalism to discuss these asymmetries, and develop an understanding of how various suppression factors distinguish between them qualitatively. We estimate the size of the asymmetries in the Standard Model: $A_{CP}(B^+\to\pi^+\pi^0)\sim 3\times10^{-3}$, $A_{CP}(D^+\to\pi^+\pi^0)\sim 10^{-5}$, and $A_{CP}(K^+\to\pi^+\pi^0)\sim 10^{-6}$

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Yuval Grossman, Zoltan Ligeti, Yosef Nir. 2026-05-05. CP asymmetries in charged meson decay to two pions. https://arxiv.org/abs/2605.04137

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