New physics in $b\to s{e}^{+}{e}^{-}$?

Abstract

At present, the measurements of some observables in $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$ and $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ decays, and of $R_{K^{(\ast )}}\equiv \mathcal{B}(B\to K^{(\ast )}{\mu }^{+}{\mu }^{-})/\mathcal{B}(B\to K^{(\ast )}{e}^{+}{e}^{-})$, are in disagreement with the predictions of the standard model. While most of these discrepancies can be removed with the addition of new physics (NP) in $b\to s{\mu }^{+}{\mu }^{-}$, a difference of $>\sim 1.7\sigma$ still remains in the measurement of $R_{K^{\ast }}$ at small values of $q^2$, the dilepton invariant mass-squared. In the context of a global fit, this is not a problem. However, it does raise the question: if the true value of $R_{K^{\ast }}^{low}$ is near its measured value, what is required to explain it? In this paper, we show that, if one includes NP in $b\to s{e}^{+}{e}^{-}$, one can generate values for $R_{K^{\ast }}^{low}$ that are within $\sim 1\sigma$ of its measured value. Using a model-independent, effective-field-theory approach, we construct many different possible NP scenarios. We also examine specific models containing leptoquarks or a $Z^{\prime }$ gauge boson. Here, additional constraints from lepton-flavour-violating observables, $B_s^0$-${\bar{B}}_s^0$ mixing and neutrino trident production must be taken into account, but we still find a number of viable NP scenarios. For the various scenarios, we examine the predictions for $R_{K^{(\ast )}}$ in other $q^2$ bins, as well as for the observable $Q_5\equiv P_5^{\prime \mu \mu }-P_5^{\prime ee}$.

16 pages, 1 figure. We have added constraints from lepton-flavour-violating observables. These eliminate the scenario with only the $U_1$ leptoquark. All other scenarios are unchanged. Apr. 12: some text and references added, in particular a "Note added" regarding the new results reported at Moriond 2019

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• Unified explanation of flavor anomalies, radiative neutrino mass and ANITA anomalous events in a vector leptoquark model
• $R_K$ and $R_{K^{\ast }}$ in an Aligned 2HDM with Right-Handed Neutrinos
• What $R_K$ and $Q_5$ can tell us about New Physics in $b\to s\ell \ell$ transitions?
• The time-dependent angular analysis of $B_d\to K_S\ell \ell$, a new benchmark for new physics
• New physics in $B\to K^{\ast }{\tau }^{+}{\tau }^{-}$: A model independent analysis
• Explaining Atomki anomaly and muon $g-2$ in $U(1{)}_X$ extended flavour violating two Higgs doublet model
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• Predictions for $B_s\to {\bar{K}}^{\ast }\ell \ell$ in non-universal $Z^{\prime }$ models
• Prospects for New Physics searches with ${\Lambda }_b\to \Lambda (1520){\ell }^{+}{\ell }^{-}$ decays
• New Physics in $b\to s\ell \ell$ anomalies and its implications for the complementary neutral current decays
• A unique discrimination between new physics scenarios in $b\to s{\mu }^{+}{\mu }^{-}$ anomalies
• Investigating the effect of $U_1$ vector leptoquark on $b\to u\tau \bar{\nu }$ mediated $B$ decays
• A Family-nonuniversal $U(1{)}^{\prime }$ Model for Excited Beryllium Decays
• Discriminating 1D new physics solutions in $b\to s\ell \ell$ decays
• New physics in $b\to s{e}^{+}{e}^{-}$: A model independent analysis
• Confronting $B$ anomalies with low energy parity violation
• Charged Lepton Flavor Violation at the High-Energy Colliders: Neutrino Mass Relevant Particles