Implications of B+→K+νν¯ under rank-one flavour violation hypothesis

mardi 1 avr. 2025, 11:00 → 12:00 Europe/Paris

Salle de Sommets

Claudio Toni

We study the implications of the observed excess at Belle-II under the assumption of Rank-One Flavour Violation, i.e. that New Physics couples to a single specific direction in flavour space. By varying this direction we perform analyses at the level of the low-energy EFT, the SMEFT, and with explicit mediators such as leptoquarks and colorless vectors. Among the various mediators, the scalar leptoquarks ${\tilde{R}}_2$ and $S_1$ offer the best fits of the Belle-II excess, while being consistent with the other bounds. On the other hand, colorless vectors are strongly constrained by meson mixing and resonance searches. In all cases we find that a flavour alignment close to the third generation is generically preferred.