Overview Search for Resonant Slepton Production with the DØ-Experiment Christian Autermann, III. Phys. Inst. A R-parity violating Supersymmetry Resonant Slepton Production and Neutralino Decay Data selection and efficiencies Control plots Preliminary Results Supported by Christian Autermann Bad Honnef, 6.-. September 24
DØ Performance Effective Luminosity used for analysis: Ldt = 54± pb -.5 fb - End of 23 shutdown Christian Autermann Bad Honnef, 6.-. September 24 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 Trilepton channel multi lepton final state Chiral superfields: L: lepton doublet superfield E: lepton singlet superfield Q: quark doublet superfield D: down-like quark singlet superfield Resonant production two muon and two jets final state Resonant production at hadronic accelerators λ, λ`, λ``: Yukawa couplings References: H. Dreiner, et.al., Search for R-Parity Violation at Run-II of the Tevatron, hep-ph/996224 N.Ghodbane, S.Katsanevas, P.Morawitz, E.Perez, SUSYGEN 3, hep-ph/999499 Christian Autermann Bad Honnef, 6.-. September 24 3
Neutralino Production & Decay resonant production decay R-parity violating production and decay Final state: two (isolated) muons two jets Other modes: sneutrino resonance 2 jets, MET & perh. µ Suppressed Modes: (not considered) neutralino pair production and decay over λ`2 t-channel slepton exchange Christian Autermann Bad Honnef, 6.-. September 24 4
Run I Exclusion Contour tan A ( β ) µ µ = = = 2. DØ Run I msugra parameters m scalar mass m /2 gauginos mass parameter A trilinear coupling term sign(µ) higgs mass mixing param. tan(β) ratio of the vacuum expect. of the neutral higgs fields m, m /2 and A are defined at the GUT scale Plots for this point, Limits for M~ χ = 75, GeV & M ~ µ = 2, 3 GeV DØ Collaboration, Phys.Rev.Letter 89 (22), hep-ex/53 Christian Autermann Bad Honnef, 6.-. September 24 5
Data Sample & Preselection Total delivered L dt = 29pb -, good & reconstructed L dt = 54pb - Data taking period April 22 September 23 Dimuon data sample ~2M events (~4% of all data) Preselection Any Dimuon trigger has fired Veto against cosmic muons (Scintillator timings) 2 muons with pt > 2 GeV, pt > 8 GeV 2 jets with pt > 5 GeV, pt > GeV 2 nd jet pt > 2 GeV OR 2 nd muon pt > 2 GeV central track match & isolation for both muons dimuon angle R µ,µ2 >. to reject QCD events 258 events (27.5 ± 8.[stat] ± 79.6[syst] expected) Christian Autermann Bad Honnef, 6.-. September 24 6
Control Plots of the Data Sample () Signal (red) is scaled up by a factor Christian Autermann Bad Honnef, 6.-. September 24 7
Control Plots of the Data Sample (2) Signal (red) is scaled up by a factor Christian Autermann Bad Honnef, 6.-. September 24 8
Dimuon Trigger Efficiency Weight all MC events according to muon (pt, η, φ), jet, MET to account for dimuon trigger inefficiencies Estimate systematic error by varying the correction factor by ± standard deviation efficiency.8.6 efficiency.4.5.2 Z/γ Z/DY * incl. MC 6-3GeV -.5 - Z/γ * Z/DY incl. MC 6-3GeV 2 3 4 5 6 7 8 9 nd 2 muon p T [GeV] -2 -.5 - -.5.5.5 2 nd 2 muon η Christian Autermann Bad Honnef, 6.-. September 24 9
Isolation Efficiency SRC track cone core i hollow cone Σ E < T E iso i p T ε Data = 8.7% ε MC = 86.9% η φ Christian Autermann Bad Honnef, 6.-. September 24
σ = k σ NLO LO Z/γ * Cross Section Cross sections from Pythia are LO. weight Z-MC events with k(m µµ ) to account for higher order corrections k-factor 2.8 Correction Factor K for LO Z/γ Z/DY * x-section NNLO k NLO = + σ 4 3 + 4 α ( 2 M S π 3 2π = k σ NNLO NNLO LO NNLO correction with CTEQ6 is used to weight the Z/γ * µµ ).6.4.2 NLO Λ + MeV NLO Λ = 29 MeV NLO Λ - MeV NNLO CTEQ6 NNLO CTEQ5 References: R. Hamberg et. al.: A COMPLETE CALCULATION OF THE ORDER ALPHA-S**2 CORRECTION TO THE DRELL-YAN K FACTOR., Nucl.Phys.B359:343-45,99 K. Hagiwara et al., Particle Data Group, Phys. Rev. D 66, (22) T. Nunneman, D Note 4476 2 * 3 (Z/γ) [GeV] M µµ Christian Autermann Bad Honnef, 6.-. September 24
Systematic Uncertainties cross sect. Uncertainty Trigger Z/γ* cross section Isolation & Tracking Jet energy scale tot. syst. error background +5.3% / 6.9% +3.% / 2.9% +3.6% / 3.6% +3% / 27% tot. syst. error signal 6% 9% 4% 8% 33% Effect on the pre-selection sample Jet Energy Scale uncertainty is the dominating systematic error (Two jets in the final state) 6.5% 3% uncertainty per jet depending on jet p T, η, φ jet p T > 25 GeV jet 2 p T > 5 GeV jet 2 p T > 2 GeV muon 2 p T > 2 GeV Christian Autermann Bad Honnef, 6.-. September 24 2
Signal MonteCarlo (SUSYGEN) Invariant mass of 2 jets and the lower energetic muon muon is from ~ χ-decay muon is from ~ µ-decay neither nor Invariant mass of 2 jets and 2 muons mass χ ~ = 2 GeV mass µ ~ = 262 GeV Generated with Susygen and passed through full detector simulation & reconstruction. Christian Autermann Bad Honnef, 6.-. September 24 3
Final Selection cut range. p T (µ ) > 2.25 GeV +.88 (M µ ~ - M χ ~ ) p T (µ )+p T (µ 2 ) > 6 GeV p T (jet ) > 25 GeV π < φ (µ,jet i ) < π +.5 < φ (µ 2,jet i ) < 2.5 9 GeV (5 GeV+M~ χ /9) < M µµ < 9 GeV+(5 GeV+M χ ~ /9) M χ ~ 4 GeV < M µ2,jet,jet2 < M χ ~ + 2 GeV M µ ~.2 M ~ µ < M µ,µ2,jet,jet2 < M µ ~ +.2 M ~ µ Christian Autermann Bad Honnef, 6.-. September 24 4
Signal Efficiencies signal efficiency [%] Constant slepton mass (2, 3 GeV) Signal Efficiency vs. Neutralino mass 6 5 4 3 Efficiency µ =2 GeV µ =3 GeV Constant Signal neutralino Efficiency mass vs. Slepton (75, mass GeV) signal efficiency [%] 8 7 6 5 4 Efficiency χ =75 GeV χ = GeV 2 4 6 8 2 4 6 Neutralino mass [GeV] 3 2 5 2 25 3 35 4 Slepton mass [GeV] The neutralino decays only with ~5% BR into two muons and two jets. Christian Autermann Bad Honnef, 6.-. September 24 5
Signal Region (m χ ~ =2GeV, m µ ~ =263GeV) Invariant dimuon mass Reconstructed smuon mass (Inv. mass of muon, muon 2, jet & jet 2 ) After all cuts for this msugra point:.±.3±.2 SM evts expected 2 data events found (4.4±.5±.8 signal events) Cut to remove the remaining Z background good agreement between data and standard model background Christian Autermann Bad Honnef, 6.-. September 24 6
Cross Section Limits limit / σ [pb] 6 4 2 Limit for a fixed neutralino mass = 75GeV and Excluded Run I λ 2 =.7 σ, χ =75 GeV, λ =.7 2 Limit 95%CL, χ =75 GeV limit / σ [pb] 6 4 2 Limit for a fixed neutralino mass = GeV and λ 2 =.7 Excluded no Run I limit σ, χ = GeV, λ 2 =.7 Limit 95%CL, χ = GeV 8 8 6 4 6 4 Control plots for this point 2 D RunII preliminary 2 D RunII preliminary 6 8 2 22 24 26 28 3 32 34 Slepton mass [GeV] 2 25 3 35 4 Slepton mass [GeV] Christian Autermann Bad Honnef, 6.-. September 24 7
Cross Section Limits limit / σ [pb] 9 8 Limit for a fixed slepton mass = 2GeV and Excluded Run I =.7 λ 2 σ, µ =2 GeV, λ 2 =.7 Limit 95%CL, µ =2 GeV limit / σ [pb] 9 8 Limit for a fixed slepton mass = 3GeV and D RunII preliminary no Run I limit =.7 λ 2 σ, µ =3 GeV, λ 2 =.7 Limit 95%CL, µ =3 GeV 7 7 6 6 5 5 4 4 3 3 2 2 D RunII preliminary 4 5 6 7 8 9 Neutralino mass [GeV] 6 8 2 4 6 Neutralino mass [GeV] Christian Autermann Bad Honnef, 6.-. September 24 8
Limits on LQD coupling λ 2 λ 2 LQD coupling.4.35.3.25 Limit for a fixed neutralino mass = 75GeV Limit 95%CL, χ =75 GeV D Run I Γ(π e ν)/γ(π µ ν) λ 2 LQD coupling.5.45.4.35.3 Limit for a fixed neutralino mass = GeV Limit 95%CL, χ= GeV no D Run I limit Γ(π e ν)/γ(π µ ν).2 Excluded.5..5 D RunII preliminary 6 8 2 22 24 26 28 3 32 34 Slepton mass [GeV].25.2.5..5 Excluded Control plots this point D RunII preliminary 2 25 3 35 4 Slepton mass [GeV] Theoretical Limit from lepton universality in the pion decay Christian Autermann Bad Honnef, 6.-. September 24 9
Limits on LQD coupling λ 2 λ 2.4 Limit for a fixed slepton mass = 2GeV Limit 95%CL, µ =2 GeV λ 2.4 Limit for a fixed slepton mass = 3GeV Limit 95%CL, µ =3 GeV LQD coupling.35.3.25.2 Excluded D Run I Γ(π e ν)/γ(π µ ν) LQD coupling.35.3.25.2 Excluded no D Run I limit Γ(π e ν)/γ(π µ ν).5.5.. Run I.5.5 D RunII preliminary 5 6 7 8 9 Neutralino mass [GeV] D RunII preliminary 6 8 2 4 6 Neutralino mass [GeV] Christian Autermann Bad Honnef, 6.-. September 24 2
Conclusions Search for RPV SUSY through the LQD coupling λ 2 in the two muons plus two jets final state Data agrees well with Standard Model expectation Exclusion limits with 95% CL have been presented, improving on Run I results Already.5 fb - data on tape: 3 times more than used for this analyses Presented at ICHEP and DPF Conference Note 4535 with more detailed information is available at http://www-d.fnal.gov/run2physics/www/results/np/np.htm Improve analysis by using more luminosity adding the neutralino (missing ET) channel Better signal selection Christian Autermann Bad Honnef, 6.-. September 24 2