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arXiv · 1610.08761

Measuring the Breaking of Lepton Flavour Universality in $B\to K^*\ell^+\ell^-$

Nicola Serra·Rafael Silva Coutinho·Danny van Dyk
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Abstract

We propose measurements of weighted differences of the angular observables in the rare decays $B \to K^*\ell^+\ell^-$. The proposed observables are very sensitive to the difference between the Wilson coefficients $\mathcal{C}_9^{(e)}$ and $\mathcal{C}_9^{(\mu)}$ for decays into electrons and muons, respectively. At the same time, the charm-induced hadronic contributions are kinematically suppressed to $\lesssim 7\% (4\%)$ in the region $1\,$GeV$^2 \leq q^2 \leq 6\,$GeV$^2$, as long as LFU breaking occurs only in $\mathcal{C}^{(\ell)}_{9}$. This suppression becomes stronger for the region of low hadronic recoil, $q^2 \geq 15\,$GeV$^2$.

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Nicola Serra, Rafael Silva Coutinho, Danny van Dyk. 2016-10-27. Measuring the Breaking of Lepton Flavour Universality in $B\to K^*\ell^+\ell^-$. https://doi.org/10.1103/physrevd.95.035029

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