Implications of $b\to s\ell^+\ell^-$ constraints on $b\to s\nu\bar\nu$ and $s\to d\nu\bar\nu$

International audienceWe investigate the consequences of deviations from the Standard Model observed in $b\to s\mu\mu$ transitions for flavour-changing neutral-current processes involving down-type quarks and neutrinos, under generic assumptions concerning the structure of New Physics. We derive the relevant Wilson coefficients within an effective field theory approach respecting the SM gauge symmetry, including right-handed currents and assuming a flavour structure based on approximate $U(2)$ symmetry, and only SM-like light neutrinos. We discuss correlations among $B \to K^{(*)} \nu \bar \nu$ and $K\to \pi \nu \bar \nu$ branching ratios in the case of linear Minimal Flavour Violation and in a more general framework, highlighting in each case the role played by various New Physics scenarios proposed to explain $b\to s\mu\mu$ deviations. This talk is based on arXiv:2005.03734