Prospects for searches of b → sν ν ¯ $$ b\to s\nu \overline{\nu} $$ decays at FCC-ee

Abstract We investigate the physics reach and potential for the study of various decays involving a b → sν ν ¯ $$ b\to s\nu \overline{\nu} $$ transition at the Future Circular Collider running electron-positron collisions at the Z-pole (FCC-ee). Signal and background candidates, which involve inclusive Z contributions from b b ¯ $$ b\overline{b} $$ , c c ¯ $$ c\overline{c} $$ and uds final states, are simulated for a proposed multi-purpose detector. Signal candidates are selected using two Boosted Decision Tree algorithms. We determine expected relative sensitivities of 0.53%, 1.20%, 3.37% and 9.86% for the branching fractions of the B 0 → K ∗ 0 ν ν ¯ $$ {B}^0\to {K}^{\ast 0}\nu \overline{\nu} $$ , B s 0 → ϕν ν ¯ $$ {B}_s^0\to \phi \nu \overline{\nu} $$ , B 0 → K S 0 ν ν ¯ $$ {B}^0\to {K}_S^0\nu \overline{\nu} $$ and Λ b 0 → Λ ν ν ¯ $$ {\Lambda}_b^0\to \Lambda \nu \overline{\nu} $$ decays, respectively. In addition, we investigate the impact of detector design choices related to particle-identification and vertex resolution. The phenomenological impact of such measurements on the extraction of Standard Model and new physics parameters is also studied.