Probing the type-II seesaw mechanism through the production of Higgs bosons at a lepton collider

We investigate the production and decays of doubly-charged Higgs bosons for the Type-II seesaw mechanism at an $e^{+}{e}^{-}$ collider with two center of mass energies, $\sqrt{s}=380\mathrm{GeV}$ and 3 TeV, and analyze the fully hadronic final states in detail. Lower mass ranges can be probed during the 380 GeV run of the collider, while high mass ranges, which are beyond the 13 TeV Large Hadron Collider discovery reach, can be probed with $\sqrt{s}=3\mathrm{TeV}$. For such a heavy Higgs boson, the final decay products are collimated, resulting in fat-jets. We perform a substructure analysis to reduce the background and find that a doubly-charged Higgs boson in the mass range 800–1120 GeV can be discovered during the 3 TeV run, with integrated luminosity $\mathcal{L}\sim 95{\mathrm{fb}}^{-1}$ of data. For 380 GeV center of mass energy, we find that for the doubly-charged Higgs boson in the range 160–172 GeV, a $5\sigma$ significance can be achieved with only integrated luminosity $\mathcal{L}\sim 24{\mathrm{fb}}^{-1}$. Therefore, a light Higgs boson can be discovered immediately during the run of a future $e^{+}{e}^{-}$ collider.

Figure 1

The Feynman diagram for $H^{++}{H}^{--}$ pair-production and its subsequent decays into gauge bosons.

Figure 2

The production cross-section at $e^{+}{e}^{-}$ collider. The center of mass energies are $\sqrt{s}=380\mathrm{GeV}$ and 3 TeV. For comparison, we also show the cross section at 13 TeV LHC. The pair-production cross section increases by a factor of two, if CLIC uses 80%, and 30% beam polarization for electron and positron beam.

Figure 3

The normalized distribution of the transverse momentum and the pseudorapidity for the produced $H^{\pm \pm }$.

Figure 4

The Feynman diagram for $H^{++}{H}^{--}$ pair-production and its subsequent decays to 4 fat-jet.

Figure 5

The $p_T$ distribution of the leading and 4th leading fat-jets. For signal, we consider $M_{H^{\pm \pm }}=1120\mathrm{GeV}$.

Figure 6

The $H_T$ distribution of the jets at the partonic level. We consider three illustrative benchmark points $M_{H^{\pm \pm }}=800$, 1120, and 1400 GeV.

Figure 7

The $\mathrm{\Delta }{R}_{WW}$ distribution of the different $W^{\pm }$, produced from the doubly charge Higgs $H^{\pm \pm }$. The $W$’s in this figure are $p_T$ ordered.

Figure 8

The invariant mass of the fat-jet(leading and 4th leading) constructed using subjets four momentum. For signal, we consider $M_{H^{\pm \pm }}=1120\mathrm{GeV}$.