  A search for new heavy resonances decaying to a pair of Higgs bosons (HH) in
proton-proton collisions at a center-of-mass energy of 13 TeV is presented.
Data were collected with the CMS detector at the LHC in 2016-2018,
corresponding to an integrated luminosity of 138 fb$^{-1}$. Resonances with a
mass between 0.8 and 4.5 TeV are considered using events in which one Higgs
boson decays into a bottom quark pair and the other into final states with
either one or two charged leptons. Specifically, the single-lepton decay
channel HH $\to$ $\mathrm{b\bar{b}}$WW$^*$ $\to$ $\mathrm{b\bar{b}}\ell\nu
q\bar{q}'$ and the dilepton decay channels HH $\to$ $\mathrm{b\bar{b}}$WW$^*$
$\to$ $\mathrm{b\bar{b}}\ell\nu \ell\nu$ and HH $\to$
$\mathrm{b\bar{b}}\tau\tau$ $\to$ $\mathrm{b\bar{b}}\ell\nu\nu \ell\nu\nu$ are
examined, where $\ell$ in the final state corresponds to an electron or muon.
The signal is extracted using a two-dimensional maximum likelihood fit of the H
$\to$ $\mathrm{b\bar{b}}$ jet mass and HH invariant mass distributions. No
significant excess above the standard model expectation is observed in data.
Model-independent exclusion limits are placed on the product of the cross
section and branching fraction for narrow spin-0 and spin-2 massive bosons
decaying to HH. The results are also interpreted in the context of radion and
bulk graviton production in models with a warped extra spatial dimension. The
results provide the most stringent limits to date for X $\to$ HH signatures
with final-state leptons and at some masses provide the most sensitive limits
of all X $\to$ HH searches.

High Energy Physics - Experiment