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Andreas Crivellin, M. Kirk
Abstract
The discrepancies between $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ data and the corresponding Standard Model predictions point to the existence of new physics with a significance at the $5\ensuremath{\sigma}$ level. While previously a lepton flavor universality violating effect was preferred, the new $R({K}^{(*)})$ and ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ measurements are now compatible with the Standard Model, favoring a lepton flavor 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 flavor violation, this poses a challenge for model building. In this article, we point out a novel possibility: a diquark, i.e., a colored scalar, induces the Wilson coefficient of the $(\overline{s}{\ensuremath{\gamma}}^{\ensuremath{\mu}}{P}_{L}b)(\overline{c}{\ensuremath{\gamma}}_{\ensuremath{\mu}}{P}_{L}c)$ operator at tree-level, which then mixes into ${O}_{9}$ via an off-shell photon penguin. This setup allows for a lepton flavor universal effect of ${C}_{9}\ensuremath{\approx}\ensuremath{-}0.5$, without violating bounds from $\mathrm{\ensuremath{\Delta}}{M}_{s}$, $\mathrm{\ensuremath{\Delta}}\mathrm{\ensuremath{\Gamma}}$, $B\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ and ${D}^{0}\ensuremath{-}{\overline{D}}^{0}$ mixing. This scenario predicts a small and negative ${C}_{9}^{\ensuremath{'}}$ and a light diquark, preferably with a mass around 500 GeV, as compatible with the CMS di-dijet analysis, and a deficit in the inclusive $b\ensuremath{\rightarrow}c\overline{c}s$ rate.