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Chiral Perturbation Theory at Two Loops and the Measurement of $V_{us}$

Johan Bijnens
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Abstract

I give an overview of the calculations done in three-flavour Chiral perturbation theory at next-to-next-to-leading order with an emphasis on those relevant for an improvement in the accuracy of the measurement of $V_{us}$. It is pointed out that all needed low energy constants can be obtained from experiment via the scalar form-factor in $K_{\ell3}$ decays

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Johan Bijnens. 2003-04-30. Chiral Perturbation Theory at Two Loops and the Measurement of $V_{us}$. https://arxiv.org/abs/hep-ph/0304284

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