A singular way to search for heavy resonances in missing energy events

Chan Beom Park

doi:10.1007/jhep07(2020)089

Abstract

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.

Highlights

The novel singularity variable has a direct correlation with the mass scale of the resonance, so it can greatly help distinguish the new physics signal from backgrounds
The algebraic singularity method was proposed from the observation that the projected visible phase space can have singularities in the presence of missing energy
The singularity variables have been devised to capture such singular features, and they implicitly provide the mass spectrum information of intermediate resonances and invisible particles in the final state. It has been outlined the prescriptions for deriving the singularity variables for various event topology with missing energy [4]

Summary

Kinematic singularity of the antler decay topology

The phase space is the hypersurface of the final-state particle momenta, subject to the kinematic constraints like energy-momentum conservation and on-shell mass relations. It is clear that kinematic variables would be more useful if they enable us to directly deduce the mass scale of heavy resonances by identifying the positions of the peak or edge of their distributions To derive such a kinematic variable, we review the singularity variable for the antler decay topology at first. Note that the two distributions overlap only at the true MX value It means that if a unique solution for eq (2.10) exists for given events, it corresponds precisely to the resonance mass. The blue distribution is obtained by assuming that the longitudinal momentum QL is known, while the red one is by setting QL = 0 when computing the variables The latter corresponds to ∆(A0T) or MA(0T)

Searching for heavy Higgs bosons decaying into a top pair

Findings

Conclusions