1. Sparticle reconstruction in dilepton final state M. Chiorboli, M. Galanti & A. Tricomi University & INFN Catania CMS Physics Review I. SUSY/BSM CERN, 20-21 September 2004

2. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Topology 2 high p t isolated leptons OS (leptons = e, ) 2 high p t (b) jets missing E t SM bkg: tt, Z+jet, W+jet, ZZ, WW, ZW, QCD jets Reconstruction of sbottoms, squarks and gluinos p p b(q)

3. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Mass reconstruction: what can be done End-point analysis: from global fit End-point analysis: from global fit Sparticle masses Sparticle masses 1 mass determination 1 mass determination Mass peak reconstructions Mass peak reconstructions p p b(q)

4. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Mass reconstruction: what exists p p b b At the end-point: Model dependence: assumed to be known Jet association 10 fb -1 sbottom sbottom chain Kinematical peculiarities can be exploited

5. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Edge analysis In sequential decays many other edges and thresholds can be extracted In sequential decays many other edges and thresholds can be extracted This was first pioneered by ATLAS This was first pioneered by ATLAS Several interesting development by Luc (see his talk ) Several interesting development by Luc (see his talk ) Combining all these information Combining all these information sparticle masses p p b(q)

6. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Plan for the new analysis TO DO LIST Status Parton level studies to exploit the feasibility of the methods (Pythia+Isajet) work in progress Fast simulation study to understand the CMS capability to reconstruct sparticles in the dilepton channel (FAMOS) playing and familiarizing with FAMOS Full simulation & reconstruction detailed study @ mSUGRA point LM1 detailed study @ mSUGRA point LM1 background study: tt, Z+jet, W+jet… background study: tt, Z+jet, W+jet… tool optimization: tool optimization: jet calibration jet calibration b tagging b tagging mass fit mass fit All to be done

7. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Present work: parton level studies Generator: Generator: 100K events with Pythia 6.224 + Isajet 7.69 100K events with Pythia 6.224 + Isajet 7.69 No particular problem encountered No particular problem encountered Lucs suggestion seems promising Lucs suggestion seems promising i.e. M ll vs M llq i.e. M ll vs M llq M lq for different M ll cuts M lq for different M ll cuts M ll vs. M llq

8. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM What is needed Signal Signal ~ 600k events for 10 fb -1 @LM1 ~ 600k events for 10 fb -1 @LM1 to be produced to be produced Bkg: tt, Z+jet, W+jet, qcd Bkg: tt, Z+jet, W+jet, qcd most important tt most important tt from past fast simulation studies Z+jet, W+jet, qcd… seem negligible from past fast simulation studies Z+jet, W+jet, qcd… seem negligible something already in production (~ 600k tt events) something already in production (~ 600k tt events)

9. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Main systematics End-point analysis End-point analysis jet resolution jet resolution knowledge of theoretical shapes knowledge of theoretical shapes Sparticle peak reconstruction Sparticle peak reconstruction uncertainty on the 1 mass from end-point analysis uncertainty on the 1 mass from end-point analysis dilepton window dilepton window jet association (how to be model independent?) jet association (how to be model independent?)

10. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Manpower Institution Institution Catania Catania People involved People involved Massimiliano Chiorboli (Post-Doc) Massimiliano Chiorboli (Post-Doc) Mario Galanti (PhD student) Mario Galanti (PhD student) Alessia Tricomi (Researcher) Alessia Tricomi (Researcher) Is enough? Is enough? it should be if no delay from HW production it should be if no delay from HW production

11. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM Summary & Plans Topology: Topology: Generators: Pythia 6.224+Isajet 7.69 Generators: Pythia 6.224+Isajet 7.69 Analysis @ point LM1: Analysis @ point LM1: Parton level studies: feasibility of edge determinations Parton level studies: feasibility of edge determinations Fast simulation: first studies with FAMOS (just started) Fast simulation: first studies with FAMOS (just started) Full simulation: OSCAR+ORCA Full simulation: OSCAR+ORCA Second stage: study CMS capability to reconstruct sparticles in dilepton channel with FAMOS in other benchmark points Second stage: study CMS capability to reconstruct sparticles in dilepton channel with FAMOS in other benchmark points Important tools: Important tools: b tagging (already involved in algo studies) b tagging (already involved in algo studies) jet calibration jet calibration Main bkg: tt Main bkg: tt

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13. Alessia Tricomi University & INFN Catania PRS Physics Review I: SUSY/BSM How to distinguish the two leptons Luc suggestion