Electroweak Penguin: b → s$$\ell \ell $$, Anomalie s, Z’

In Sect. 2.2, we discussed the effects of the \(b\rightarrow s\bar{q}q\) electroweak penguin interfering with the strong penguin and tree amplitudes. The quintessential electroweak penguin would be \(b\rightarrow s\ell ^+\ell ^-\) decay, or \(b\rightarrow s\nu \nu \) that has no photonic contribution. We now discuss how the study of these processes, present already in SM, could help us probe New Physics. Besides presenting some background development, we begin with the forward-backward asymmetry \(A_\mathrm{FB}(B\rightarrow K^*\ell ^+\ell ^-)\) as a probe of the bsZ vertex, and the subsequent unfolding of the \(P_5^\prime \) and \(R_{K^{(*)}}\) anomalies. We comment briefly on a possible \(Z^\prime \) boson as a source for generating effective \([\bar{s}b][\bar{\ell }\ell ]\) (and \([\bar{s}b][\bar{\nu }\nu ]\)) four-fermi interactions. The \(b\rightarrow s\nu \nu \) process has the same signature as \(b\rightarrow s+\) nothing. A later chapter extends the signature as a probe of light Dark Matter