Explaining the $$R_K$$ RK and $$R_{K^*}$$ RK∗ anomalies
Abstract Recent LHCb results on $$R_{K^*}$$ RK∗ , the ratio of the branching fractions of $$B \rightarrow K^* \mu ^+ \mu ^-$$ B→K∗μ+μ- to that of $$B \rightarrow K^* e^+ e^-$$ B→K∗e+e- , for the dilepton invariant mass bins $$q^2 \equiv m_{\ell \ell }^2 = $$ q2≡mℓℓ2= [0.045–1.1] GeV$$^2$$ 2 and [1.1...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2017-10-01
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| Series: | European Physical Journal C: Particles and Fields |
| Online Access: | http://link.springer.com/article/10.1140/epjc/s10052-017-5282-y |
| Summary: | Abstract Recent LHCb results on $$R_{K^*}$$ RK∗ , the ratio of the branching fractions of $$B \rightarrow K^* \mu ^+ \mu ^-$$ B→K∗μ+μ- to that of $$B \rightarrow K^* e^+ e^-$$ B→K∗e+e- , for the dilepton invariant mass bins $$q^2 \equiv m_{\ell \ell }^2 = $$ q2≡mℓℓ2= [0.045–1.1] GeV$$^2$$ 2 and [1.1–6] GeV$$^2$$ 2 show approximately $$2.5 \sigma $$ 2.5σ deviations from the corresponding Standard Model prediction in each of the bins. This, when combined with the measurement of $$R_K \, (q^2=[1-6]\, \mathrm GeV^2)$$ RK(q2=[1-6]GeV2) , a similar ratio for the decay to a pseudo-scalar meson, highly suggests lepton non-universal new physics in semi-leptonic B meson decays. In this work, we perform a model independent analysis of these potential new physics signals and identify the operators that do the best job in satisfying all these measurements. We show that heavy new physics, giving rise to $$q^2$$ q2 independent local 4-Fermi operators of scalar, pseudo-scalar, vector or axial-vector type, is unable to explain all the three measurements simultaneously, in particular $$R_{K^*}$$ RK∗ in the bin [0.045–1.1], within their experimental $$1\sigma $$ 1σ regions. We point out the possibility to explain $$R_{K^*}$$ RK∗ in the low bin by an additional light ($$\lesssim \, 20 \, {\mathrm{MeV}}$$ ≲20MeV ) vector boson with appropriate coupling strengths to ($$\bar{b} \, s$$ b¯s ) and ($$\bar{e} \, e$$ e¯e ). |
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| ISSN: | 1434-6044 1434-6052 |