Search for Supersymmetry with the CMS - Detector Aachen 3a SUSY Group: Markus Merschmeyer, Arnd Meyer, Prof. Thomas Hebbeker, Holger Pieta, Daniel Teyssier 29. August 2007
Supersymmetry SUSY at CMS Computing, Software, and Analysis challenge (CSA07) Outlook
SM works well on most known physical phenomena, but there are some questions: Why strong interaction strong and the weak interaction weaker? Why does mass spectrum of fermions stretch over almost six orders of magnitudes between the e and the top-quark? Is there a unification coupling? What is dark matter? Theory for gravity?
Supersymmetry approach: Find an operator Q with Q fermion >= boson > and Q boson >= fermion > every SM particle has a supersymmetric partner (sparticle) SUSY particle has a spin difference S = 1/2 particle mass = sparticle mass? sparticles should have been found, but haven t symmetry must be broken (masses differ) many new free parameters
Minimal Supersymmetric Standard Model (MSSM) minimal number of new particles: one for each SM-particle more then 100 new free parameters R-Parity conserved lightest supersymmetric particle (LSP) stable, neutral dark matter? Some parameters restricted e.g.: Lepton-mixing has not been observed µ e + γ no large electric dipole moments of electrons or muons only 22 free parameters left
SM Spin 1/2 ( el,r ν ( el ul,r d L,R ), ), ( µl,r ν ( µl cl,r s L,R ), ), ( τl,r ν ( τl tl,r b L,R ) ) Susy Particle Spin 1 ) ) (ẽl,r ( µl,r,, ν el ν µl ) ( cl,r, (ũl,r d L,R ), s L,R ( τl,r ν τl ) ) ( t L,R b L,R SM Spin 1,0 neutral bosons: γ, Z, h, H, A charged bosons: W ±, H ± gluon: g Susy Particle Spin 1/2 neutralinos: χ 0 1, χ0 2, χ0 3, χ0 4 charginos: χ ± 1, χ± 2, χ± 3, χ± 4 gluino: g
Minimal Supergravity (msugra) L SUSY invariant under local gauge transformations naturally leads to gravitino (S=3/2) and graviton (S=2) further restriction: only 5 free parameters They are with unification of: gaugino masses, sfermion an Higgs boson masses, trilinear coupling: m 0 common boson mass m 1/2 common gaugino mass A 0 universal trilinear coupling sign(µ) sign of Higgs mixing tan(β) ratio of vacuum expectation values for Higgs fields
Benchmark Points Still 5 free parameter, how to scan this big space? choose some points, influenced by other experiments e.g. LEP, cosmic exclusion limits from WMAP easier comparison between other experiments
Benchmark Points low mass Points LM high mass points HM low crossection
LM points 1-9: between σ =6.24 pb (LM6) and 40.5 pb (LM1), (LO pythia) HM points: between σ =0.045 pb (HM1) and 0.116 pb (HM4), (LO pythia)
Supersymmetry SUSY at CMS Computing, Software, and Analysis challenge (CSA07) Outlook
The Compact Muon Solenoid (CMS) detector
Supersymmetry SUSY at CMS Computing, Software, and Analysis challenge (CSA07) Cavern lowering of 19.1. YB+2 CMS livecam 27.8. Outlook
Supersymmetry SUSY at CMS Computing, Software, and Analysis challenge (CSA07) Outlook
CMS Software (CMSSW) simulation of the detector and reconstruction of particles combining detector hits Monte Carlo input (GEN): different MC generators e.g. PYTHIA, SHERPA, cosmic muon generator... detectorsimulation with GEANT 4 (SIM) digitalization (DIGI): what the detector would have measured reconstruction (RECO): get physics objects combining several hits still under construction
Philosophy of CMSSW modular desgin control modules over configuration file path p1 = {psim} # simulation module include Configuration/EventContent/data/EventContent.cff module GEN SIM = PoolOutputModule { using FEVTSIMEventContent untracked string filename = LM5 isasdkpyt GEN SIM.root untracked PSet dataset ={ untracked string datatier = GEN SIM } } endpath outpath = {GEN SIM} schedule = {p1,outpath}
Accessing Data in the CMSSW software data (C++ objects) stored in ROOT Trees technical: access these objects over a data branch with a specified label, e.g.: Handle<MuonCollection> muonhandle; event.getbylabel( globalmuons, muonhandle); MuonCollection mouns = MuonHandle; MuonCollection::const iterator muon; for (muon = mouns.begin(); muon!= mouns.end(); ++muon){ cout << ( muon) >pt() << endl; }
Create Data Branches possibility to create new data objects e.g. isolated mouns new label = globalmuonisolated CMSSW provides tools: Producers and Filters Producer: create a new data Branch e.g. clean muons from fake muons label = cleanedmuons Filter: filter an existing data Branch e.g. make a muon cut of 10 GeV label = muonspt10
CMSSW is not complet some parts are missing or not ready have to create/filter new branches e.g do own object cleaning SUSY Tools common analysis framework for SUSY working group stay in the CMSSW framwork use CMSSW mechanisms access objects over lables as before store new objects / make them available for other modules everyone can access new data as before using lables Future: port existing tools (e.g. SUSY-Analyser) to SUSY Tools
Looking at the channel µ + missing E T (MET) + Jets Mouns have a clear siganture SUSY events have high MET from LSP many Jets in the SUSY cascades
First SUSY plots (preselection): p T (Jet) > 10GeV, η < 2.5 p T (µ) > 15GeV, η < 2.4 (Daniel Teyssier) higher p T in Jets for LM1 low energie mouns
Supersymmetry SUSY at CMS Computing, Software, and Analysis challenge (CSA07) Outlook
Testing of the CMS computing system (GRID)
Scheduled Tasks produce big MC samples run skims (create subsample) over this sample test data transfers between differents sites Goals reconstruction of events at CERN (TIER 0) at 100 Hz for 30 days data transfer from CERN to FZK Karlsruhe (TIER 1) 300 MB/s data transfer from FZK to RWTH (TIER 2) between 20-200 MB/s skims at TIER 1 Search for Supersymmetry user analysis with the CMS at TIER - Detector2, target 75000 jobs/day
MC Production Susy LM points generate low mass points LM1 - LM 11 calculate the SUSY spectrum with ISASUGRA and SOFTSUSY calculate decay widths and the branching ratios with SDECAY 100K events/point with PYTHIA Background samples QCD min 1 µ or 1 e TTbar incl WW,ZZ,WZ incl
Skiming for the SUSY working group usefull for final state µ + Jet + MET: 2 µ + 0 electrons + 2 Jets + MET (p T (e) > 5 GeV,p T (µ) > 3 GeV, p T (Jet) > 80 GeV, MET > 50 GeV) 1 µ + 1 electrons + 2 Jets + MET (p T (e) > 5 GeV,p T (µ) > 3 GeV, p T (Jet) > 80 GeV, MET > 50 GeV) 1 µ + 0 electrons + 1 Jets + MET (p T (e) > 5 GeV,p T (µ) > 3 GeV, p T (Jet) > 50 GeV, MET > 50 GeV)
Data Transfer with Phedex
Outlook keep an eye on the RWTH grid cluster, to play a big role in CSA07 work on SUSY-tools focus on a SUSY analysis (µ + Jet + MET) look at a certain LM Point work together with Model Independent Searches to be sensitive to all points?
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