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R-parity violation at DØ. Run I results and Run II prospects

PHENO 2002 SYMPOSIUM. R-parity violation at DØ. Run I results and Run II prospects. On behalf of the DØ collaboration Auguste Besson (ISN-Grenoble, France). R-parity violation at DØ. The TeVatron and the DØ detector R-parity violating SUSY (RPV) Pair production and RPV decays of LSP

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R-parity violation at DØ. Run I results and Run II prospects

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  1. PHENO 2002 SYMPOSIUM R-parity violation at DØ.Run I results and Run II prospects On behalf of the DØ collaboration Auguste Besson (ISN-Grenoble, France) Auguste Besson

  2. R-parity violation at DØ • The TeVatron and the DØ detector • R-parity violating SUSY (RPV) • Pair production and RPV decays of LSP •  and ’ couplings • Resonant sparticle production • ’ and ’’ couplings • Top decay via RPV • ’ and ’’ couplings • Conclusion and outlook Auguste Besson

  3. Run 1b Run 2a Run 2b #bunches 6 x 6 36 x 36 140 x 103 s (TeV) 1.8 1.96 1.96 typ L (cm-2s-1) 1.6x1030 8.6x1031 5.2x1032  Ldt (fb-1) ~ 0.13 ~ 2 ~ 15 bunch xing (ns) 3500 396 132 interactions/xing 2.5 2.3 4.8 TeVatron DØ CDF MI. + Recycler The TeVatron • Run II started March 2001 • Increased Luminosity • Main injector, Recycler • # bunches, # antiprotons • Increased Energy • 1.8 to 1.96 TeV Auguste Besson

  4. Run IIa current Luminosity • typical Luminosity • ~ 1031 cm-2s-1 • Integrated L • ~ 36 pb-1 delivered Auguste Besson

  5. The DØ upgrade • Run I • excellent calorimetry LAr/U, hermetic, compensation • Run II upgrade • New tracking Silicon tracker Fiber tracker • Central solenoid 2 Teslas - Preshower - Forward muon system - Electronics - Triggers Auguste Besson

  6. Supersymmetry • SUSY • - New symmetry between fermions and bosons • - Solves hierarchy problem • - allows convergence of coupling constants at GUT scale • - complete new spectrum of susy particles. • In most of the models • - SUSY particles are pair produced • - The lightest SUSY particle (LSP) is stable and escape from detector. Auguste Besson

  7. R-parity • SUSY potential: • i,j,k = 1,2,3(family indices)  9 + 27 + 9 = 45 new Yukawa couplings. • Lepton ( and ’) or Baryon (’’) number not conserved •  define R-parity : discrete quantum number • B= Baryon nb, L=nb Lepton nb, S=spin • Rp= +1  SM particle • Rp= -1  SUSY particle •  not excluded theoritically With Rp = (-1)3B+2S+L Auguste Besson

  8. R-parity violating : consequences • The Lightest Susy Particle (LSP) decays either • - inside the detector (with or without a displaced vertex) • outside the detector (similar to Rp conserved analysis) • Susy signature can be very different • Less missing Et • More leptons ( or ’) and jets (’ or ’’) • Single Susy particle production is possible • via ’ or ’’ @ TeVatron • LSP is not anymore a candidate for dark matter (-1) (+1) (+1) (+1) Auguste Besson

  9. RPV Experimental constraints • Indirect limits via low energy processes • e-- universality - Neutrinoless double-beta decay - Charged current universality - Top decay - Atomic parity violation - etc. • 2 limits for m = 100 GeV (limits often linear in mass) • Stronger limits on products of coupling -proton decay : ’’11k . ’11k < 10-22 ~ Barger et al. Phys.Rev. D40 (89) Ledroit, Sajot GDR-S-008 (98) Allanach et al., PRD 60 (99) ~ dk e+ _ u p d d u u Auguste Besson

  10. RPV search at DØ : hypothesis • mSUGRA framework (m0 ; m1/2 ; A0 ; sign  ; tan ) • LSP • Only one Yukawa coupling (ijk,’ijk,’’ijk) dominates • Pair production  all pair production included, then 2 LSP decay via RPV. • If RPV coupling is large  resonant production is possible Auguste Besson

  11. Pair production: dielectron channel • 2 susy particles produced  2 LSP • Dominant coupling ’1jk (j=1,2 ; k=1,2,3) • If LSP decays inside the detector: coupling not to small,(’1jk >~ 10-3) LSP  1 e + 2 jets • Background: Drell-Yan, tt, Ze+e- + jets, misidentification of jets as electrons • Cuts: pTel  15 & 10 GeV; pTjet  15 GeV; Mee  76-106 GeV Final State : 2 electrons + 4 jets _ _ Auguste Besson

  12. Dielectron channel : m0-m1/2 plane A0 = 0 ;  < 0 ; tan  = 2 D0, Phys. Rev. Lett. 83, 4476 (99) • Run I results : L = 99 pb-1 , s = 1.8 TeV - Expected Backgd : 1.8  0.2  0.3 - Events observed : 2 • Run II : L = 2fb-1, s = 2 TeV • Scenario I Extrapolation from Run I • Scenario II upgraded detector ~ mg ~ 550 GeV mq ~ 500 GeV ~ Run II : Allanach et al. hep-ph/9906224 Auguste Besson

  13. Pair production: dimuon channel • Similar analysis • Dominant coupling ’2jk • Backgd : Drell-Yan, tt, Z+jets, Z,WW + jets • Cuts : pT > 15 & 10 GeV, pTjets > 15 GeV, Scalar ET > 150 GeV, M>5GeV, Acoplanarity > 0.03 • Run I : L = 77.5  4 pb-1 Events observed = 0 Expected Background = 0.18  0.03  0.02 Final State : 2 muons + 4 jets Auguste Besson

  14. dimuon channel : m0-m1/2 plane A0 = 0 ;  < 0 ; tan  = 2 Run II (2fb-1) Run I D0, hep-ex/0111053 Submitted to PRL. Auguste Besson

  15. Pair production: multileptons channel • Dominant coupling 121, 122 or233 LSP  2 charged leptons + 1  • Backgd: Drell-Yan, tt, Z, misidentification of jets as electrons • Run I : Final State :  eee,ee,e, + missing ET D0, PRL 80, 1592 (1998) D0, Phys. Rev. D Rapid. Comm.62, 071701 (2000) Auguste Besson

  16. multileptons channel : m0-m1/2 plane • Contours : • 121, 122 or233  < 0 or > 0 tan  = 5, 10 Auguste Besson

  17. e1 e2 e3 ET = 17.9 GeV pT = 0.52 GeV  = 0.43  = 5.42 Charge= +1 ET = 13.9 GeV pT = 10.9 GeV  = -1.94  = 2.80 Charge= +1 ET = 13.2 GeV pT = 15.1 GeV  = 1.06  = 5.72 Charge= -1 me1e2 = 55.7 me1e3 = 10.8 me2e3 = 63.5 me1e2e3 = 85.2GeV/c2MET =10.7 GeV eee candidate event D Run 2 Preliminary Trilepton eventsare classical SUSY signature Electron Electrons Auguste Besson

  18. MET e 1 2 pT = 28.2 GeV  = -0.10  = 6.20 Charge = -1 pT = 9.82 GeV  = -1.48  = 2.88 Charge = 1 ET = 19.2 GeV  = 0.40  = 0.63 No track match m = 41.5 GeV/c2 MET =31.8 GeV emm candidate event D Run 2 Preliminary Muon system Electron Muon Muon Auguste Besson

  19. ~ ~ ~  1- 1o _ d Resonant production : dimuons channel • Dominant coupling ’211  resonant prod via RPV • Decay of LSP via RPV • Backgd : tt, Z+2jets, WW+jets • Cuts : pT  20 GeV ; pTjets  20 GeV Scalar ET  50 GeV ; Rjets  0.5 _ ~ 1o ~ u u d L _ _ d  u d l - d W - Final State :  2  + 2 jets l + Auguste Besson

  20. Dimuons in m0-m1/2 plane A0 = 0 ;  < 0 ; tan  = 2 preliminary • Run I: L = 94  5 pb-1 Events observed = 5 Expected Background = 5.34  0.07 95% conf. level • Run II: • (Fast simulation) • ’211=0.05 A0 = 0 ;  < 0 ; tan  = 1.5 Déliot et al., EPJ C 19 (01) 155 Auguste Besson

  21. ~ ~ ~  1- 1o _ d Resonant production : 3 leptons channel u d Final State : 3  + 2 jets l - d W - l + Mass reconstruction Fast simulation: M̃01=77.7 GeV (MC input) 2 jets and softer muon: M̃01=71 GeV (9) Lint = 10fb-1 ’211 = 0.09 A0 = 0 ;  < 0 ; tan  = 1.5 Déliot et al., EPJ C 19 (01) 155 Auguste Besson

  22. ~ 1o ~ l 1+ ~ d t W l s b Resonant Squark Production • Dominant coupling ’’3jk  Resonant stop production  Stop decays to b  to which decays outside the detector • Backgd: W+b-fake,Wbb,Wcc, single top • Cuts: pTb > 40 GeV ; pTlepton > 20 GeV;no other lepton or jet • Run I: 110 pb-1 Final State : 1 charged lepton, 1 b-jet + missing ET Berger et al.,PRD 63, 115001 (01) Auguste Besson

  23. Resonant Squark Production • Run II studies : ’’3jk , 2 fb-1 • Perspectives with Fast simulation (SHW) Berger et al.,PRD 63, 115001 (01) Auguste Besson

  24. 5.00 2.00 1.00 0.50 0.20 0.10 0.05 ’’331 150 160 170 180 190 Sbottom Mass (GeV) Top decay via RPV : Run II studies _ • ’’331 dominant coupling • tt production  t bd  t W-b lb • decays outside the detector • Backgd : tt, Wbbj • Cuts : pT> 20 GeV, || < 2.5, Rjj > 0.5 • Run II studies (fast simulation, 2fb-1) + ’’333 studies _ _ _ Final state: 1 lepton + 2 b-jets + 1 jet + ETmiss _ Han et al. Phys. Lett.B 476 79 (2000) Abraham et al. Phys.Lett.B 514 72 (2001) Eilam et al. Phys.Lett.B510227 (2001) Auguste Besson

  25. Conclusion • RUN I : many channels and couplings explored • RUN IIa : • improved detector ; Lint10 ; 10% more energy • DØ is already taking data. ~ 300 pb-1 expected at the end of 2002. ~ 2 fb-1 in 2004. • Great discovery potential both in pair/single production. No RPV signal found Auguste Besson

  26. Feynman diagrams • Via ’122 Auguste Besson

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