1. SUSY particles searches with R-parity violation at DØ, Tevatron
SUSY particles searches with R-parity violation at DØ, Tevatron. (λ121 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 λ121 coupling
i) Production: Rp conserved  pair of Charginos-Neutralinos, mainly Z* f W* f
Production of a pair of
ii) Decay: Rp violated with λ121 coupling  Decay of the neutralinos into leptons. eμ ee
Final state: eeee, eeeμ, or eeμμ
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 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.
Zee, Zμμ, Zττ between 5 and 1960 GeV,
WWlυlυ, 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 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 = 250
m1/2 = 195
tanβ = 5
μ < 0
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

5. A 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 understanding of 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 + 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 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)
Σbkg
DATA
(310 pb-1)
0.7 ± 0.4 (stat) ± 0.2 (sys)
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 : 238 pb-1
(*)
(*)
(*) W.Beenakker et al PRL 83 (1999) 3780
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

10. Anne-Marie Magnan --- LPSC Grenoble
Present preliminary limits: more luminosity (310 pb-1) and better selection cuts
tanβ = 5, A0 = 0
Theoretical x-sect
σ95 experimental limit
m0 = 100 GeV
m0 = 250 GeV
m0 = 500 GeV
μ < 0
Not yet approuved
249 GeV
μ > 0
Not yet approuved
271 GeV
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

11. Limits we can obtain in (m0,m1/2) , and on Mχo1
Susygen (scan) v , suspect v2.3
m0 (GeV)
m1/2 (GeV)
m0 (GeV)
m1/2 (GeV)
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

12. Anne-Marie Magnan --- LPSC Grenoble
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:
λ133 , μ > 0
Theoretical x-sect
σ95 experimental limit
m0 = 50 GeV, tanβ=5
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

13. Results 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 λ121 coupling
Dilepton Invariant mass with
m0 = 200, m1/2 = 700.
Selection: at least 3 leptons (e, μ) and 2 jets (pTe > 20 GeV, pTμ > 10 GeV, pTjets > 50 GeV.)
tanb = 2, μ < 0
Lint = 10 fb-1.
5-sigma reach contour for λ223 = 0.06 (lower curve)
and λ121 = 0.05 (upper curve).
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

15. Conclusion 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. Anne-Marie Magnan --- LPSC Grenoble
Backup
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

17. Tevatron and DØ detector
s = ~2 TeV
Time between collisions = ~400 ns.
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

18. Central detectors view
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble

19. Anne-Marie Magnan --- LPSC Grenoble
Some 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)
25/11/2004 Euro-GRD Supersymmetry
Anne-Marie Magnan --- LPSC Grenoble