Hunting New Animalcula with Rare K and B Decays

Abstract

We summarize the recent strategy for an efficient hunting of new animalcula with the help of rare K and B decays that avoids the use of the $V_{cb}$ and $V_{ub}$ parameters that are subject to tensions between their determinations from inclusive and exclusive decays. In particular we update the values of the $V_{cb}$-independent ratios of various K and B decay branching ratios predicted by the Standard Model. We also stress the usefulness of the $V_{cb}-\gamma$ plots in the search for new physics. We select the magnificant seven among rare K and B decays that should play a leading role in the search for new physics due to their theoretical cleanness: $B^{+}\to K^{+}(K^{\ast })\nu \bar{\nu }$ and $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ measured recently by Belle II and NA62, respectively, $K_L\to {\pi }^0\nu \bar{\nu }$ investigated by KOTO and also $B_{s,d}\to {\mu }^{+}{\mu }^{-}$ and $K_S\to {\mu }^{+}{\mu }^{-}$ measured by the LHCb, CMS and ATLAS experiments at CERN. %

Comments: 14 pages, 3 Figures,Talk given at QCD@Work 2024, Trani, June 2024. arXiv admin note: substantial text overlap with arXiv:2307.15737 V2: new references added, Comments at the end of section 3 and in the item 7 of the Summary added