Dark matter particle spectroscopy at the LHC: generalizing MT2 to asymmetric event topologies

• Published in: The journal of high energy physics Vol. 2010; no. 4
• Main Authors: Konar, Partha, Kong, Kyoungchul, Matchev, Konstantin T., Park, Myeonghun
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 21.04.2010; Springer Nature B.V
• Subjects: Asymmetry; Children; Classical and Quantum Gravitation; Dark matter; Elementary Particles; High energy physics; Large Hadron Collider; Particle decay; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Relativity Theory; String Theory; Subsystems; Topology; Transverse momentum; Supersymmetry Phenomenology
• ISSN: 1029-8479
• DOI: 10.1007/JHEP04(2010)086

We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem M T2 variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different “children” particles. In this more general approach, the endpoint M T2 ( max ) of the M T2 distribution now gives the mass of the parent particles as a function of two input children masses and . We propose two methods for an independent determination of the individual children masses M ( a ) c and M ( b ) c . First, in the presence of upstream transverse momentum PUTM the corresponding function is independent of PUTM at precisely the right values of the children masses. Second, the previously discussed M T2 “kink” is now generalized to a “ridge” on the 2-dimensional surface . As we show in several examples, quite often there is a special point along that ridge which marks the true values of the children masses. Our results allow collider experiments to probe a multi-component dark matter sector directly and without any theoretical prejudice.