Searching for di-Higgs signatures of light charged scalars

A bstract The excess in $$ t\to b\overline{b}c $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>t</mml:mi> <mml:mo>→</mml:mo> <mml:mi>b</mml:mi> <mml:mover> <mml:mi>b</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>c</mml:mi> </mml:math> observed by ATLAS points towards a charged Higgs boson with a mass around 130 GeV, consistent with the expectations from the B anomalies, i.e. $$ {R}_{D^{\left(\ast \right)}} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>R</mml:mi> <mml:msup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mo>∗</mml:mo> </mml:mfenced> </mml:msup> </mml:msub> </mml:math> and b → sℓ + ℓ − data. As a non-minimal flavour structure is required for an explanation of these observables, this points towards a two-Higgs-doublet model with generic Yukawa couplings. Such a scenario predicts a sizable cross section for the pair production of the charged Higgs at the Large Hadron Collider, which can be tested by recasting SM di-Higgs searches. While the predicted event rate is even higher than the one of SM Higgs pair production, the smaller efficiency (w.r.t. SM Higgs pair production) reduces the signal yield. Nonetheless, dedicated searches can probe most of the interesting parameter space and lead to a discovery with Run-3 or High-Luminosity LHC data.