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arXiv · hep-ph/9403390

$K_{l4}$ - Decays Beyond One Loop

J. Bijnens·G. Colangelo·J. Gasser
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Abstract

The matrix elements for $K\rightarrow ππłν$ decays are described by four form factors $F,G,H$ and $R$. We complete previous calculations by evaluating $R$ at next-to-leading order in the low-energy expansion. We then estimate higher order contributions using dispersion relations and determine the low-energy constants $L_1,L_2$ and $L_3$ from data on $K_{e4}$ decays and on elastic pion scattering. Finally, we present predictions for the slope of the form factor $G$ and for total decay rates.

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J. Bijnens, G. Colangelo, J. Gasser. 1994-03-30. $K_{l4}$ - Decays Beyond One Loop. https://doi.org/10.1016/0550-3213(94)90634-3

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