Search for Resonant Slepton Production with DØ

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1 Overview Search for Resonant Slepton Production with DØ Christian Autermann, III. Phys. Inst. A, RWTH Aachen Event Topology Data Selection and Efficiencies Control Plots Selection Optimization Preliminary Exclusion Limits Outlook Supported by Christian Autermann DPG Berlin,

2 R-parity Violating Supersymmetry R - parity : W W R/ P = = W 2 MSSM ijk R P + i = ( ) W j R/ P k 3B+ L+ 2S ' λ L L E + λ L Q D + ijk i S is the particle spin, B is the baryon number, L is the lepton number j k '' λ ijk U i D j D k R-parity violating extension of the MSSM i,j,k =,2,3 generation indices production ± χ, χ Resonant production via λ 2 of smuon or sneutrino µ,ν µ µ,ν µ Chiral superfields: L: lepton doublet superfield Q: quark doublet superfield D: down-like quark singlet superfield λ, λ`, λ``: Yukawa couplings Christian Autermann DPG Berlin,

3 Slepton Decay Channels Final State consists of 2 jets and up to two muons or missing E T Huge background from multi-jet processes Need to select events with at least 2 muons µ µ d u 2 Muon Channels: Golden channel if l is a muon No ν, no missing E T Possible to reconstruct the neutralino and the slepton mass But only 25% branching ratio u ν µ d ν µ Other channels with MET and a second muon from cascade processes Not possible to reconstruct the slepton mass and not necessarily the neutralino mass. But higher branching ratio Christian Autermann DPG Berlin,

4 Data Sample & Preselection Data from April 22 August 24 good recorded Luminosity: 347 pb - (preliminary) Preselection Sample Any Dimuon trigger has fired Veto against cosmic muons (Scintillator timings) 2 good muons with pt > 2 GeV, pt > 8 GeV central track match & isolation for both muons events, expected background: 2 984±67(stat)±54(syst) event Corrected for - Dimuon Trigger efficiency - Isolation efficiencies - Track finding & matching - Muon reconstruction efficiencies - Muon momentum smearing - Jet energy scale - Monte Carlo LO NNLO cross section Christian Autermann DPG Berlin,

5 Data Consistency: Preselection () number of events /.8 GeV Reconstructed Z-mass Statistics Data Signal, point # QCD from Data inv. di-muon mass [GeV] tt->ll tt->l+jet Y Y s 2 s WW->µνµν WZ incl. ZZ incl. 5-5GeV 5-6GeV 4 5-6GeV 5 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV 5-6GeV 5 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV Dominant SM MC is Z/γ µµ QCD is estimated from Data by a) using data events with like-sign, nearly isolated muons b) data events with b-tag Best agreement with method (b). Signal x Other considered but negligible SM backgrounds: ttbar ll, ttbar ljet Z ττ Y(s), Y(2s) W µν ZZ, WZ, WW Christian Autermann DPG Berlin,

6 Data Consistency: Preselection (2) Transverse Momentum of jet Reconstructed χ nd Mass with 2 µ number of events /.5 GeV data Statistics Data Signal, point # QCD from Data signal x tt->ll tt->l+jet 5-5GeV Z/γ GeV 4 5-6GeV 5 6-3GeV 4 Z/γ 5-6 GeV Z/γ ->µµ 6-3GeV GeV 25-5GeV Z/γ ->µµ 5-GeV QCD, b-tag data 5-6GeV 5 tt ll Ys 2 Ys WW->µνµν WZ incl. ZZ incl. 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV number of events / 8. GeV data signal x Statistics Data Signal, point # QCD from Data tt->ll tt->l+jet Z/γ ->µµ 5-6GeV 4 Z/γ GeV 5 6-3GeV 4 Z/γ 5-6 GeV QCD tt ll Z/γ ->µµ 6-3GeV GeV Ys 2 Ys WW->µνµν WZ incl. ZZ incl. 25-5GeV 5-GeV 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV jet p T [GeV] inv. mass of µ 2, jet, jet 2 [GeV] Signal x Signal x Christian Autermann DPG Berlin,

7 Corrections & Efficiencies 2µ Trigger Jet energy scale Data eff. MC correction factor 92.8 ± 6.8 % f( p T, η, φ, jet, ME T ) f(p T,η,φ, ME T ) f(p T,η,φ, ME T ) jet jet jet jet jet jet correction factor.8 Di-muon Trigger Efficiency Muon pt smear. f(p T muon ).6 mean.928 ±.68 NNLO MC x-sec. corr. f( inv. µ mass ).4.2 di-µ trigger eff. ± σ syst. error µ reconstr. Data eff. 9.3 ±.2% MC factor.974 ±.26 stat. uncertainty [GeV] µ 2 p T medium µ 97. ±.%.6 ±.6 µ track µisolation 99.8 ±.% 94.4 ±.2%. ±..988 ±.2 Total muon efficiency: 8 ± 5 % Christian Autermann DPG Berlin,

8 2D Cuts Final selection Final signal selection on Preselection & with di-jets: slepton neutralino mass plane channel separation several other 2D cuts in planes with -di-µ mass - missing E T - R(µ µ 2 ) -µ p T +µ p T - inv. di-jet mass - sum of jet p T - R(jet jet 2 ) Each 2D cut is done when the signal efficiency purity is larger than a certain limit. [GeV] inv. mass of µ 2, jet, jet 2 Reconstructed Slepton & Neutralino Mass inv. mass of µ, µ 2, jet, jet 2 [GeV] Christian Autermann DPG Berlin, channel with MET Statistics Data Signal, point # QCD from Data Signal tt->ll tt->l+jet 5-6GeV 4 5-6GeV 5 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV 6-3GeV 4 6-3GeV GeV 25-5GeV 5-GeV Ys 2 Ys WW->µνµν WZ incl. ZZ incl. golden channel High signal purity can be achieved Strong dependence on msugra point All cut parameters for each 2D cut and each msugra point are optimized

9 Data Consistency (3) Cut Flow An exemplary cutflow for the SUSY point m =2 GeV, m /2 =243 GeV: Jet cuts 2D cuts Christian Autermann DPG Berlin,

10 Preliminary Results 44 points in total Good agreement between data and SM at all points Bayesian 95%CL Excl. Limits using Poisson statistics λ 2 =.7 only relevant for cross section, not for kinematics fixed msugra param.: A = sign µ = - tan β = 5 Christian Autermann DPG Berlin,

11 Exclusion Contour in m m /2 plane A =, tanβ=5, sign(µ)=, λ 2 =.7 [GeV] m / τ is LSP 95% CL Exclusion Contour Gen. points (excluded) Gen. points (not excluded) preliminary χ= GeV χ=65 GeV χ higgsino higgs mass mass mixing, µ µ [GeV] 5 l=3 GeV l=2 GeV [GeV] m 6 Christian Autermann DPG Berlin,

12 Limit vs. neutralino mass Fixed parameters: A =, sign(µ)=, tan β = 5, λ 2 =.7 limit,σ [pb] 3 25 Slepton mass = 2 GeV D RunII preliminary σ tot, l=2gev, tan(β)=5 σ, l χ +l Limit 95% CL, λ 2 =.7 limit,σ [pb] Slepton mass = 3 GeV D RunII preliminary σ tot, l=3gev, tan(β)=5 σ, l χ +l Limit 95% CL, λ 2 = Not allowed Not allowed 5 Excluded Neutralino mass χ [GeV] Excluded Neutralino mass χ [GeV] Christian Autermann DPG Berlin,

13 Limit vs. slepton mass Fixed parameters: A =, sign(µ)=, tan β = 5, λ 2 =.7 limit,σ [pb] 3 25 Neutralino mass = 65 GeV D RunII preliminary σ tot, χ =65GeV, tan(β)=5 σ, l χ +l Limit 95% CL, λ 2 =.7 limit,σ [pb] 4 2 Neutralino mass = GeV D RunII preliminary σ tot, χ =GeV, tan(β)=5 l χ σ, +l Limit 95% CL, λ 2 = Not allowed Not allowed 5 Excluded Slepton mass l [GeV] 2 Excluded Slepton mass l [GeV] Christian Autermann DPG Berlin,

14 Conclusions Search for RPV SUSY through the LQD coupling λ 2 Well understood 2 muon preselection sample All efficiencies and systematic errors measured Efficient 2D final selection cuts Comparison with other algorithms like Neural Nets Improved limits compared to DØ Run I Cover more space in the m m /2 plane Publish Results Christian Autermann DPG Berlin,