New Physics in $b \to s \mu^+ \mu^-$ after the Measurement of $R_{K^*}$

Understand

The recent measurement of $R_{K^*}$ is yet another hint of new physics (NP), and supports the idea that it is present in $b\to s\mu^+\mu^-$ decays.

• We perform a combined model-independent and model-dependent analysis in order to deduce properties of this NP.
• Like others, we find that the NP must obey one of two scenarios: (I) $C_9^{\mu\mu}({\rm NP}) < 0$ or (II) $C_9^{\mu\mu}({\rm NP}) = - C_{10}^{\mu\mu}({\rm NP}) < 0$.
• A third scenario, (III) $C_9^{\mu\mu}({\rm NP}) = - C_{9}^{\prime \mu\mu}({\rm NP})$, is rejected largely because it predicts $R_K = 1$, in disagreement with experiment.