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CMS Physics Review I. SUSY/BSM CERN, 20-21 September 2004. Sparticle reconstruction in dilepton final state. M. Chiorboli, M. Galanti & A. Tricomi University & INFN Catania. Topology. Reconstruction of sbottoms, squarks and gluinos. b(q). p. b(q). p. 2 high p t isolated leptons OS
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CMS Physics Review I. SUSY/BSM CERN, 20-21 September 2004 Sparticle reconstruction in dilepton final state M. Chiorboli, M. Galanti & A. Tricomi University & INFN Catania
Topology Reconstruction of sbottoms, squarks and gluinos b(q) p b(q) p • 2 high pt isolated leptons OS (leptons = e,m) • 2 high pt (b) jets • missing Et SM bkg: tt, Z+jet, W+jet, ZZ, WW, ZW, QCD jets PRS Physics Review I: SUSY/BSM
End-point analysis: from global fit Sparticle masses c1 mass determination Mass peak reconstructions p b(q) b(q) p Mass reconstruction: what can be done PRS Physics Review I: SUSY/BSM
p b 10 fb-1 b p sbottom chain Kinematical peculiarities can be exploited 10 fb-1 sbottom Mass reconstruction: what exists At the end-point: Model dependence: assumed to be known Jet association PRS Physics Review I: SUSY/BSM
p b(q) b(q) p Edge analysis • In sequential decays many other edges and thresholds can be extracted • This was first pioneered by ATLAS • Several interesting development by Luc (see his talk) • Combining all these information sparticle masses PRS Physics Review I: SUSY/BSM
Plan for the new analysis PRS Physics Review I: SUSY/BSM
Present work: parton level studies • Generator: • 100K events with Pythia 6.224 + Isajet 7.69 • No particular problem encountered • Luc’s suggestion seems promising • i.e. Mll vs Mllq • Mlq for different Mll cuts Mll vs. Mllq PRS Physics Review I: SUSY/BSM
What is needed • Signal • ~ 600k events for 10 fb-1 @LM1 • to be produced • Bkg: tt, Z+jet, W+jet, qcd • most important tt • from past fast simulation studies Z+jet, W+jet, qcd… seem negligible • something already in production (~ 600k tt events) PRS Physics Review I: SUSY/BSM
Main systematics • End-point analysis • jet resolution • knowledge of theoretical shapes • Sparticle peak reconstruction • uncertainty on the c1 mass from end-point analysis • dilepton window • jet association (how to be model independent?) PRS Physics Review I: SUSY/BSM
Manpower • Institution • Catania • People involved • Massimiliano Chiorboli (Post-Doc) • Mario Galanti (PhD student) • Alessia Tricomi (Researcher) • Is enough? • it should be if no delay from HW production PRS Physics Review I: SUSY/BSM
Summary & Plans • Topology: • Generators: Pythia 6.224+Isajet 7.69 • Analysis @ point LM1: • Parton level studies: feasibility of edge determinations • Fast simulation: first studies with FAMOS (just started) • Full simulation: OSCAR+ORCA • Second stage: study CMS capability to reconstruct sparticles in dilepton channel with FAMOS in other benchmark points • Important tools: • b tagging (already involved in algo studies) • jet calibration • Main bkg: tt PRS Physics Review I: SUSY/BSM
How to distinguish the two leptons Luc suggestion PRS Physics Review I: SUSY/BSM