  A hypothetical scalar mixed with the standard model Higgs appears in few
contexts of new physics. This study addresses the question what mass range is
in the reach of $14$ TeV LHC given different magnitudes of mixing angle
$\alpha$, where event simulations are based on production from vector boson
fusion channel and decays into SM leptons through ${\rm WW}$ or ${\rm ZZ}$. It
indicates that heavy scalar mass up to $539$ GeV and $937$ GeV can be excluded
by integrated luminosity of $300$ $\rm{fb}^{-1}$ and $3000$ $\rm{fb}^{-1}$
respectively for $\sin^{2}\alpha$ larger than $0.04$.
