25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 1
SUSY particles searches with R-parity SUSY particles searches with R-parity violation at Dviolation at DØ, Tevatron.Ø, Tevatron.
(λ(λ121121 coupling) coupling)
Introduction
Analysis
Results
Comparison with other experiments
Conclusion and prospects
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 2
Final state with Final state with λλ121121 coupling coupling
Production of a pair of 01
~
i) Production: Rp conserved pair of Charginos-Neutralinos, mainly
1~0
2~
Final state: eeee, eeeμ, or eeμμ
02
~01
~
Z* ff
1
~01
~
W* ff
ii) Decay: Rp violated with λ121 coupling Decay of the neutralinos into leptons.
01
~
121~ e
e
01
~
e
e
~
121
01
~
e
e
~
121
01
~
e
e~
121
eμ eμee ee
iii) Detector not fully efficient we search for ee+X, X = e or μ
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 3
Data sample and SM backgroundData sample and SM background
• DØ Run II DATA: from sept 2002 to june 2004
310 ± 20 pb-1. preselection : {2 EM objects pT > 7 GeV.c-1} or {1 EM + 1 μ both pT > 5 GeV.c-1.}
• Standard Model (SM) background: all processes with ee or eμ final states, generated with Pythia, Alpgen.
– Zee, Zμμ, Zττ between 5 and 1960 GeV,
– WWlυlυ, WZ, ZZ,
– W lυ
– ttbar ll,
– Υ(1s)(2s) ee, Υ(1s)(2s) μμ
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 4
Main selection criteriaMain selection criteria
- at least 3 isolated leptons between them and from jets, in fiducial zones.
- “tight” electrons: standard cuts on the shape of the cluster in EM calorimeter, requirement of a track in the inner tracking system.
- “tight” muons: identified from inner tracking system to last muon chamber.
- Triggers: one OR two EM objects, OR one muon and one EM object.
m0 = 250m1/2 = 195tanβ = 5μ < 0
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 5
A example of trigger effectA example of trigger effect
• Selection of 2 tight electrons, triggered by a jet trigger ( unbiaised sample), how many do also trig an EM or a DIEM trigger ?
• EM trigger 100% efficient after 50 GeV, 15% eff at 10 GeV.• DIEM triggers 100% efficient after 30 GeV, 50% eff at 10 GeV
we need both triggers …
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 6
Plots to check our understandingPlots to check our understandingof the dataof the data
After selection of 2 tight electrons.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 7
Cuts applied to select ee + XCuts applied to select ee + X
• Cuts to remove background:• Z, WZ, ZZ ,
cut on invariant mass of any ee pair Mee [80,100] GeV.c-2.
• Z+jets ll+jets, and a “b” jet which decays into a muon,
cut on isolation of the muon
• γ conversion in e+e-,
require hits in inner tracker layers
• We expect transverse missing energy in the signal
cut on MET > 15 GeV.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 8
Remaining events and efficienciesRemaining events and efficiencies
Zee Zττ
0.50 ± 0.35(stat) ± 0.15(sys) 0.07 ± 0.11(stat) ± 0.13(sys)
tt WW,WZ,ZZ
0.04 ± 0.03(stat) ± 0.06(sys) 0.10 ± 0.04(stat) ± 0.10(sys)
ΣΣbkgbkg DATADATA
(310 pb(310 pb-1-1))
0.7 ± 0.4 (stat) ± 0.2 (sys)0.7 ± 0.4 (stat) ± 0.2 (sys) 00
Selection efficiency on signal :
~ 14 % for μ < 0~ 13.5% for μ > 0.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 9
Limits for summer 04 conferences :Limits for summer 04 conferences :238 pb238 pb-1-1
(*) W.Beenakker et al PRL 83 (1999) 3780
(*) (*)
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 10
Present preliminary limits: more luminosity Present preliminary limits: more luminosity (310 pb(310 pb-1-1) and better selection cuts) and better selection cuts
μ < 0
Not yet approuved
249 GeV249 GeV
tanβ = 5, A0 = 0
μ > 0
Not yet approuved
271 GeV271 GeV
Theoretical x-sect σ95 experimental limit m0 = 100 GeV m0 = 250 GeV m0 = 500 GeV
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 11
Limits we can obtain in (m0,mLimits we can obtain in (m0,m1/21/2) ,) ,
and on Mand on Mχχoo11
m0 (GeV)
m1/
2 (G
eV)
m0 (GeV)
m1/
2 (G
eV)
Susygen (scan) v3.00-43, suspect v2.3
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 12
Other couplings ?Other couplings ?
• We have to set limits with λ133 coupling to be conservative studied by Anne-Catherine Le-Bihan (IReS, France) , with eeτ final states.– To see how we are sensitive at λ133 coupling with ee (e or μ)
final states:
Theoretical x-sect σ95 experimental limit m0 = 50 GeV, tanβ=5
λ133 , μ > 0
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 13
Results from other experimentsResults from other experiments
• DØ Run I : limits in (m0, m1/2), for μ < 0 and μ > 0,
tanβ = 5, 10, with λ121 and λ122 couplings.
• CDF Run I: stop mass limits λ’ couplings.
• LEP: limits on mχo1 > 39 GeV and χ±
1 > 103 GeV, for λ133 coupling, available for all λ couplings.
• H1 : limits on λ’1j1(j=1,2) vs msquarks, and in (m0,m1/2),
• CMS : preliminary study with λ121 and λ122 couplings.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 14
CMS results with CMS results with λλ121121 coupling coupling
Dilepton Invariant mass withm0 = 200, m1/2 = 700.Selection: at least 3 leptons (e, μ) and 2 jets (pTe > 20 GeV, pTμ > 10 GeV, pTjets > 50 GeV.)
5-sigma reach contour for λ223 = 0.06 (lower curve) and λ121 = 0.05 (upper curve).
tanb = 2, μ < 0Lint = 10 fb-1.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 15
Conclusion and prospectsConclusion and prospects
• Anne-Catherine Le-Bihan (IReS) is working on λ133
coupling with eeτ final states,
• Daniela Kaefer (Aachen, Germany) is also working on λ122 coupling with μμ+X (=e or μ) final states.
• We should have combined results for those 3 couplings for Winter 05 conferences.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 16
BackupBackup
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 17
Tevatron and DTevatron and DØ detectorØ detector
s = ~2 TeVTime between collisions = ~400 ns.
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 18
Central detectors viewCentral detectors view
25/11/2004 Euro-GRD Supersymmetry Anne-Marie Magnan --- LPSC Grenoble 19
Some words on R-paritySome words on R-parity
• SUSY particles production: masses and couplings depend on 5 parameters (mSugra model) :
m0 , m1/2, sign(μ), tanβ, A0.In our analysis, m0 = 250 GeV, tanβ = 5, A0 = 0.
• R-parity number : Rp = (-1)3B + 2S + L Rp = +1 for standard
particles. Rp = -1 for susy particles.
• R-parity violating superpotential: The couplings between susy and standard particles fall into three classes:
- λijk (leptonic final state),- λ’ijk (leptonic + hadronic final state)- λ’’ijk (hadronic final state).
i,j,k = e,μ,τ or (u,d), (c,s), (t,b)
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