SUSY particles searches with R-parity violation at D Ø, Tevatron. (λ 121 coupling)

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


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


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


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


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 …


Plots to check our understandingPlots to check our understandingof the dataof the data

After selection of 2 tight electrons.


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.


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.


Limits for summer 04 conferences :Limits for summer 04 conferences :238 pb238 pb-1-1

(*) W.Beenakker et al PRL 83 (1999) 3780

(*) (*)


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


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


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


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.


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.


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.


BackupBackup


Tevatron and DTevatron and DØ detectorØ detector

s = ~2 TeVTime between collisions = ~400 ns.


Central detectors viewCentral detectors view


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)

Documents

SUSY particles searches with R-parity violation at D Ø, Tevatron. (λ 121 coupling)