$4b + X$ via electroweak multi-Higgs production as smoking gun signals for Type-I 2HDM at the LHC

Extending the Standard Model (SM) by one additional Higgs doublet leads to the Two-Higgs Doublet Model (2HDM). A specific charge assignment of the SM fermions under the $\mathbb{Z}_2$ symmetry leads to the Type-I 2HDM. A key feature of the Type-I 2HDM is that all the additional Higgs bosons can be fermiophobic, when their couplings to the SM fermions are suppressed. As a result, all the new Higgs states can be fairly light, $\sim$100 GeV or less, without being in conflict with the current data from the direct Higgs boson searches and the $B$-physics measurements. In a recent study Ref.~\cite{Mondal:2023wib}, which this proceeding is based on, we established that the new neutral as well as the charged Higgs bosons in this model can all be simultaneously observable in the multi-$b$ final state. An experimental validation of our results would be a clear indication that the true underlying Higgs sector in nature is the Type-I 2HDM.
Comment: Talk given by PS at the International Workshop on Future Linear Colliders (LCWS2024), University of Tokyo, Japan