  The phase space of visible particles in missing energy events may have
singularity structures. The singularity variables are devised to capture the
singularities effectively for given event topology. They can greatly improve
the discovery potential of new physics signals as well as to extract the mass
spectrum information at hadron colliders. Focusing on the antler decay topology
of resonance, we derive a novel singularity variable whose distribution has
endpoints directly correlated with the resonance mass. As a practical
application, we examine the applicability of the singularity variable to the
searches for heavy neutral Higgs bosons in the two-Higgs doublet model.
