Sparticle reconstruction in dilepton final state
description
Transcript of Sparticle reconstruction in dilepton final state
Sparticle reconstruction Sparticle reconstruction in dilepton final statein dilepton final state
M. Chiorboli, M. Galanti & A. M. Chiorboli, M. Galanti & A. TricomiTricomi
University & INFN CataniaUniversity & INFN Catania
CMS Physics Review I. SUSY/BSMCERN, 20-21 September 2004
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
TopologyTopology
2 high pt isolated leptons OS
(leptons = e,)
2 high pt (b) jets
missing EtSM bkg: tt, Z+jet, W+jet, ZZ, WW, ZW, QCD jets
g~ pp
b(q)02
~
Reconstruction of sbottoms, squarks and Reconstruction of sbottoms, squarks and gluinosgluinos
p
p
g~
b~
b(q)
b(q)
01
02
~)~(
~qqbb
01
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Mass reconstruction: what can be doneMass reconstruction: what can be done
End-point analysis: from global End-point analysis: from global fitfit Sparticle massesSparticle masses 1 1 mass determinationmass determination
Mass peak reconstructionsMass peak reconstructions
p
p
g~
b~
b(q)
b(q)
01
02
~
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Mass reconstruction: what existsMass reconstruction: what exists
p
p
g~
b~
b
b
01
02
~
p
M
M1p
01
02
At the end-point:At the end-point:
Model dependence:
assumed to be known
Jet association
01
M
10 fb-1
sbottomsbottom
10 fb-1
sbottom sbottom chainchain
Kinematical Kinematical peculiarities can be peculiarities can be
exploitedexploited
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Edge analysisEdge analysis
In sequential decays many In sequential decays many other edges and thresholds can other edges and thresholds can be extractedbe extracted
This was first pioneered by This was first pioneered by ATLASATLAS
Several interesting Several interesting development by Luc (see his development by Luc (see his talktalk))
Combining all these Combining all these informationinformation
sparticle masses sparticle masses
p
p
g~
b~
b(q)
b(q)
01
02
~
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Plan for the new analysisPlan for the new analysisTO DO LISTTO DO LIST StatusStatusParton level studies to exploit the Parton level studies to exploit the feasibility of the methods feasibility of the methods (Pythia+Isajet) (Pythia+Isajet)
work in progresswork in progress
Fast simulation study to understand Fast simulation study to understand the CMS capability to reconstruct the CMS capability to reconstruct sparticles in the dilepton channelsparticles in the dilepton channel (FAMOS) (FAMOS)
playing and familiarizing playing and familiarizing with FAMOSwith FAMOS
Full simulation & reconstructionFull 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 calibrationjet calibration
b taggingb tagging
mass fitmass fit
All to be doneAll to be done
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Present work: parton level studiesPresent work: parton level studies
Generator: Generator: 100K events with 100K events with
Pythia 6.224 + Isajet Pythia 6.224 + Isajet 7.69 7.69
No particular problem No particular problem encounteredencountered
Luc’s suggestion Luc’s suggestion seems promisingseems promising i.e. Mi.e. Mllll vs M vs Mllqllq
MMlqlq for different M for different Mllll cuts cuts
Mll vs. Mllq
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
What is neededWhat is needed
SignalSignal ~ ~ 600k events for 10 fb600k events for 10 fb-1 -1 @LM1@LM1 to be producedto be produced
Bkg: tt, Z+jet, W+jet, qcdBkg: tt, Z+jet, W+jet, qcd most important ttmost important tt from past fast simulation studies Z+jet, from past fast simulation studies Z+jet,
W+jet, qcd… seem negligibleW+jet, qcd… seem negligible something already in production (something already in production (~ ~
600k tt events)600k tt events)
10tan
0
)(
60
250
00
21
A
sign
m
m
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Main systematicsMain systematics
End-point analysisEnd-point analysis jet resolutionjet resolution knowledge of theoretical shapesknowledge of theoretical shapes
Sparticle peak reconstructionSparticle peak reconstruction uncertainty on the uncertainty on the 11 mass from end- mass from end-
point analysispoint analysis dilepton windowdilepton window jet association (how to be model jet association (how to be model
independent?)independent?)
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
ManpowerManpower
InstitutionInstitution CataniaCatania
People involvedPeople 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 it should be if no delay from HW
productionproduction
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
Summary & PlansSummary & 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 determinationsParton 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+ORCAFull simulation: OSCAR+ORCA Second stage: study CMS capability to reconstruct sparticles Second stage: study CMS capability to reconstruct sparticles
in dilepton channel with FAMOS in other benchmark pointsin 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: ttMain bkg: tt
01
02
02
~ ;b(q))q~(b~
);~(~~ qqbbg
backupbackup
PRS Physics Review I: SUSY/BPRS Physics Review I: SUSY/BSMSM
Alessia TricomiUniversity & INFN Catania
How to distinguish the two leptonsHow to distinguish the two leptons
Luc suggestion