Diquark Explanation of $b\to s\ell^+\ell^-$

Le résumé fourni par la source

The discrepancies between $b\to s\ell^+\ell^-$ data and the corresponding Standard Model predictions point to the existence of new physics with a significance at the $5σ$ level. While previously a lepton flavour universality violating effect was preferred, the new $R(K^{(*)})$ and $B_s\toμ^+μ^-$ measurements are now compatible with the Standard Model, favouring a lepton flavour universal beyond the Standard Model contribution to $C_9$. Since heavy new physics is generally chiral, and because of the stringent constraints from charged lepton flavour violation, this poses a challenge for model building. In this article, we point out a novel possibility: a diquark, i.e. a coloured scalar, induces the Wilson coefficient of the $(\bar s γ^μP_L b) (\bar c γ_μP_L c)$ operator at tree-level, which then mixes into $O_9$ via an off-shell photon penguin. This setup allows for a lepton flavour universal effect of $C_9\approx-0.5$, without violating bounds from $ΔM_s$, $ΔΓ$, $B\to X_sγ$ and $D^0-\bar D^0$ mixing. This scenario predicts a small and negative $C_9^{\prime}$ and a light diquark, preferably with a mass around $500\,$GeV, as compatible with the CMS di-di-jet analysis, and a deficit in the inclusive $b\to c\bar c s$ rate.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.