2025/03/24 by Bolton, Patrick D., Fajfer, Svjetlana, Kamenik, Jernej F. +1 · 3 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2503.19025
Motivated by a recent Belle~II measurement that suggests an excess in the rare decay B → K E\rm miss, and building upon our recent differential decay rate likelihood analysis of the existing experimental information, we investigate possible new physics (NP) scenarios in which light invisible states participate in flavour-changing b → s transitions. In particular, we consider the total and differential B→ K^* E\rm miss decay rates and K^* polarisation effects in each NP scenario preferred by the B→ K E\rm miss measurement. We show that future measurements of these B → K^* E\rm miss observables will offer decisive discrimination among the different NP explanations. Our results highlight the strong complementarity of the rare semi-invisible b-hadron decay observables, and underline the importance of analysing their momentum transfer spectra when probing extensions of the Standard Model that feature new light degrees of freedom.