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

Understand

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.