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arXiv · 1805.08189

Towards a viable scalar interpretation of $R_{D^{(*)}}$

Sean Fraser·Carlo Marzo·Luca Marzola·Martti Raidal·Christian Spethmann
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Abstract

Recent measurements of semileptonic B-meson decays seemingly imply violations of lepton flavor universality beyond the Standard Model predictions. With three-level explanations based on extended Higgs sectors being strongly challenged by the measurements of the $B_c^-$ lifetime, new theories invoking leptoquark or vector fields appear as the only feasible answer. However, in this work we show that simple scalar extensions of the Standard Model still offer a possible solution to the $B$ physics puzzle, owing to sizeable loop-level corrections which mimic the effects of new vector contributions. Considering a simplified model characterised by a charged and a neutral scalar particle, we verify the compatibility of the observed $R_{D^{(*)}}$ signal with the relevant collider bounds. We also study an embedding of the simplified model into a three-Higgs-doublet framework, and investigate its main phenomenological constraints.

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Sean Fraser, Carlo Marzo, Luca Marzola, Martti Raidal, Christian Spethmann. 2018-05-21. Towards a viable scalar interpretation of $R_{D^{(*)}}$. https://doi.org/10.1103/physrevd.98.035016

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