Improved mass measurement using the boundary of many-body phase space

Abstract

We show that mass measurements for new particles appearing in decay chains can be improved by determining the boundary of the available phase space in its full dimensionality rather than by using one-dimensional kinematic features for each stage of the cascade decay. This is demonstrated for the case of one particle decaying to three visible and one invisible particles in a two-stage cascade, but our methods also apply to a more general set of decay topologies. We show that not only mass differences, but also the overall scale of masses can be determined with high precision without having to rely on cross section information. The improvement arises from the properties of the higher dimensional phase space itself, independent of the matrix element for the decay, and it is not weakened by the presence of intermediate on-shell particles in the cascade. Our results are particularly significant for the case of low signal statistics, a distinct possibility for new physics searches in the near future.

37 pages, 10 figures. References added, discussion of simplifying assumptions expanded, minor modifications in the text. Matches journal version

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Cited by in corpus (10)

• Using Energy Peaks to Measure New Particle Masses
• Detecting kinematic boundary surfaces in phase space: particle mass measurements in SUSY-like events
• Identifying Phase Space Boundaries with Voronoi Tessellations
• Enhancing the discovery prospects for SUSY-like decays with a forgotten kinematic variable
• Singularity Variables for Missing Energy Event Kinematics
• Multi-Dimensional Phase Space Methods for Mass Measurements and Decay Topology Determination
• Finding Wombling Boundaries in LHC Data with Voronoi and Delaunay Tessellations
• Discovering New Physics with Voronoi Tessellations
• Applying Machine Learning Techniques To Intermediate-Length Cascade Decays
• Could $M_{T2}$ be a singularity variable?