Search for a light charged Higgs boson decaying to a W boson and a CP-odd Higgs boson in final states with e$\mu\mu$ or $\mu\mu\mu$ in proton-proton collisions at $\sqrt{s} =$ 13 TeV
Phys.Rev.Lett. 123 (2019) 131802, 2019.
The collaboration

Abstract (data abstract)
A search for a light charged Higgs boson ($\mathrm{H^{+}}$) decaying to a W boson and a CP-odd Higgs boson (A) in final states with $\mathrm{e}\mu\mu$ or $\mu\mu\mu$ is performed using data from pp collisions at $\sqrt{s}=13$ TeV, recorded by the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 fb$^{-1}$. In this search, it is assumed that the $\mathrm{H}^{+}$ boson is produced in decays of top quarks, and the A boson decays to two opposite-charge muons. The presence of signals for $\mathrm{H}^{+}$ boson masses between 100 and 160 GeV and A boson masses between 15 and 75 GeV is investigated. No evidence for the production of the $\mathrm{H^{+}}$ boson is found. Upper limits at 95% confidence level are obtained on the combined branching fraction for the decay chain, $\mathrm{t}\to\mathrm{bH^{+}}\to\mathrm{bW^{+}A}\to\mathrm{bW^{+}}\mu^{+}\mu^{-}$, of $1.9\times10^{-6}$ to $8.6\times10^{-6}$, depending on the masses of the $\mathrm{H^{+}}$ and A bosons. These are the first limits for these decay modes of the $\mathrm{H^{+}}$ and A bosons.

Version 2 modifications: As a result of the journal reviews, the upper limits are now given on the product of branching fractions, B(t->bH+)*B(H+->WA)*B(A->mumu). In the version prior to the review, B(t->bH+) was given, assuming B(H+->WA)=1 and B(A->mumu)=3e-4. Hence, only the way the measurements are presented has changed.