Resonant Higgs boson pair production in the $hh\rightarrow b\bar{b} \; WW \rightarrow b\bar{b} \ell^+ \nu \ell^- \bar\nu$ decay channel

Adding a scalar singlet provides one of the simplest extensions of the Standard Model. In this work we briefly review the latest constraints on the mass and mixing of the new Higgs boson and study its production and decay at the LHC. We mainly focus on double Higgs production in the $hh \rightarrow b \bar{b} WW \rightarrow b \bar{b} \ell^+ \nu \ell^- \bar{\nu}$ decay channel. This decay is found to be efficient in a region of masses of the heavy Higgs boson of 260 - 500 GeV, so it is complementary to the 4$b$ channel, more efficient for Higgs bosons having masses greater than 500 GeV. We analyse this di-leptonic decay channel in detail using kinematic variables such as $M_{\rm T2}$ and the $M_{\rm T2}$-assisted on-shell reconstruction of invisible momenta. Using proper cuts, a significance of $\sim$ 3$\sigma$ for 3000 fb$^{-1}$ can be achieved at the 14 TeV LHC for $m_H$ = 260 - 400 GeV if the mixing is close to its present limit and ${\rm BR}(H \rightarrow hh) \approx 1$. Smaller mixing values would require combining various decay channels in order to reach a similar significance. The complementarity among $ H \rightarrow hh$, $ H \rightarrow ZZ$ and $ H \rightarrow WW$ channels is studied for arbitrary ${\rm BR}(H \rightarrow hh)$ values.