  We demonstrate the ability to measure the CP-phase of a Higgs boson state by
looking at the decays of heavy, Majorana neutrinos in the process $pp \to H \to
N N$ at the LHC. This is shown for signals with both opposite-sign ($l^{\pm}
l^{\mp} W^{\pm} W^{\mp}$) and same-sign ($l^{\pm} l^{\pm} W^{\mp} W^{\mp}$)
leptonic final states. These signals are investigated in the general framework
of a sequential fourth generation of fermions with an additional right-handed
neutrino. Such a scenario would naturally give rise to heavy Majorana neutrinos
as well as significant enhancements to Higgs production via gluon fusion due to
the contributions of the new, heavy quark states running in the fermion loops.
Combined with the low background inherent to a same-sign lepton signal, this
could be a useful way to investigate the CP-nature of a Higgs boson state at
the LHC.
