Improved transverse-mass variable for detecting Higgs-boson decays intoZpairs

A promising decay mode for detecting heavy Higgs bosons at a supercollider is H→ZZ →($l^{+}$ $l^{\mathrm{-}}$)(νν¯), with one Z detected by $e^{+}$ $e^{\mathrm{-}}$ or ${\mu }^{+}$ ${\mu }^{\mathrm{-}}$ decay and the other decaying to undetected neutrinos. Such events peak versus the transverse mass of the detected Z. We show there is an even sharper peak versus the two-body transverse mass, incorporating the missing transverse momentum carried by the second Z boson.