∆Ms theory precision confronts flavour anomalies

Abstract

Abstract Based on recent HQET sum rule and lattice calculations we present updated Standard Model predictions for the mass differences of neutral B mesons: $$ \varDelta {M}_s^{\mathrm{SM}}=\left({18.4}_{-1.2}^{+0.7}\right){\mathrm{ps}}^{-1} $$ Δ M s SM = 18.4 − 1.2 + 0.7 ps − 1 and $$ \varDelta {M}_d^{\mathrm{SM}}=\left({0.533}_{-0.036}^{+0.022}\right){\mathrm{ps}}^{-1} $$ Δ M d SM = 0.533 − 0.036 + 0.022 ps − 1 study their impact onnew physics models that address the present hints of anomalous data in b → sℓℓ transitions. We also examine future prospects of further reducing the theory uncertainties and discuss the implications of a 2025 scenario with $$ \varDelta {M}_s^{\mathrm{SM}\;2025}=\left(18.4\pm 0.5\right) $$ Δ M s SM 2025 = 18.4 ± 0.5 ps −1. In particular, the latter yields upper bounds M Z′ ≲ 9TeV and $$ {M}_{S_3}\lesssim 30\mathrm{TeV} $$ M S 3 ≲ 30 TeV for the minimal Z′ and S 3 lepto-quark explanations of the b → sℓℓ anomalies, respectively.