The Precision Determination of Invisible-Particle Masses at the LHC

Abstract

We develop techniques to determine the mass scale of invisible particles pair-produced at hadron colliders. We employ the constrained mass variable m_2C, which provides an event-by-event lower-bound to the mass scale given a mass difference. We complement this variable with a new variable m_2C,UB which provides an additional upper bound to the mass scale, and demonstrate its utility with a realistic case study of a supersymmetry model. These variables together effectively quantify the `kink' in the function Max m_T2 which has been proposed as a mass-determination technique for collider-produced dark matter. An important advantage of the m_2C method is that it does not rely simply on the position at the endpoint, but it uses the additional information contained in events which lie far from the endpoint. We found the mass by comparing the HERWIG generated m_2C distribution to ideal distributions for different masses. We find that for the case studied, with 100 fb^-1 of integrated luminosity (about 400 signal events), the invisible particle's mass can be measured to a precision of 4.1 GeV. We conclude that this technique's precision and accuracy is as good as, if not better than, the best known techniques for invisible-particle mass-determination at hadron colliders.

20 pages, 11 figures, minor corrections

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Cited by in corpus (12)

• Using Subsystem MT2 for Complete Mass Determinations in Decay Chains with Missing Energy at Hadron Colliders
• Minimal Kinematic Constraints and MT2
• \sqrt{s}_min: a global inclusive variable for determining the mass scale of new physics in events with missing energy at hadron colliders
• Using kinematic boundary lines for particle mass measurements and disambiguation in SUSY-like events with missing energy
• Handling jets + missing E_T channel using inclusive mT2
• Precise reconstruction of sparticle masses without ambiguities
• Mass determination in sequential particle decay chains
• Precision Determination of Invisible-Particle Masses at the CERN LHC: II
• Effects of QCD radiation on inclusive variables for determining the scale of new physics at hadron colliders
• A Simple Mass Reconstruction Technique for SUSY particles at the LHC
• Determining Reheating Temperature at LHC with Axino or Gravitino Dark Matter
• Mass Determination of New Particle States