Supersymmetry at DØ and other new phenomena searches in Run II – TeVatron and DØ upgrade – Run II preliminary studies mSUGRA : squarks and gluinos jet + mET mSUGRA : squarks and gluinos jet + mET GMSB : diphotons GMSB : diphotons RPV : trileptons / likesign dileptons RPV : trileptons / likesign dileptons Extra-dimensions Extra-dimensions Auguste BESSON for the D0 collaboration PASCOS 2003

PASCOS January 2003Auguste Besson for D0 collab. 2 TeVatron upgrade Main Injector & Recycler Tevatron  p source Booster pp p CDF DØ p-pbar colliderp-pbar collider Run IIa : march 2001Run IIa : march 2001 Energy: 1.8  1.96 TeVEnergy: 1.8  1.96 TeV LuminosityLuminosity –new injector : main injector –# bunches : 6 x 6 → 36 x 36 –pbar production  –pbar recycling : Recycler (Run IIb) Fermilab

PASCOS January 2003Auguste Besson for D0 collab. 3 TeVatron upgrade (2) Run 1b Run 2a Run 2 upgrade time start p/bunch (10 11 ) pbar/bunch (10 10 ) # bunches 6 x 6 36 x x 103 bunch length (cm) time between bunch (ns) ~ # interactions/crossing crossing angle (  rad) crossing angle (  rad)00136 p/p emittance (mm mrad) 23  /13  20  /15   s (TeV) Instantaneous L (10 31 cm -2 s -1 ) Instantaneous L (10 31 cm -2 s -1 ) ∫Ldt (pb -1 /week) integrated ∫Ldt (fb -1 ) ~ 0.13 ~

PASCOS January 2003Auguste Besson for D0 collab. 4 Run IIa : current luminosity ∫L.dt on tape ∫L.dt on tape ~ 50 pb -1 (october 2002) ~ 50 pb -1 (october 2002) ~ 75 pb -1 (mid-december 2002) ~ 75 pb -1 (mid-december 2002) date Maximum Luminosity Maximum Luminosity = 3.6 x cm -2 s -1 = 3.6 x cm -2 s -1 Delivered luminosity Delivered luminosity ~ 150 pb -1 ~ 150 pb -1 (9 december 2002) week

PASCOS January 2003Auguste Besson for D0 collab. 5 The DØ collaboration ~ 650 physicists; 76 institutions; 18 countries

PASCOS January 2003Auguste Besson for D0 collab. 6 DØ upgrade Run IRun I -Calorimeter LAr/U, compensate Run II upgradeRun II upgrade -tracking Silicon vertex Fiber tracker -solenoid 2 T magnetic field -Preshower -Muons detector -Electronics - Trigger system

PASCOS January 2003Auguste Besson for D0 collab. 7

MSSM / mSUGRA productionCross-sections Run II preliminary study: squarks/gluinos

PASCOS January 2003Auguste Besson for D0 collab. 9 Susy production Neutralinos/charginosNeutralinos/charginos –trilepton channel –dilepton channel sleptons cross-section small.sleptons cross-section small. squarks/gluinossquarks/gluinos –jet + mET –single  + jets + mET stops and sbottomstops and sbottom b 1  b  2 0   1 0 e + e - ~ ~ ~

PASCOS January 2003Auguste Besson for D0 collab. 10 cross-section (mSUGRA) For m 1/2 > 100 GeV and m 0 > 100 GeV pair production of Charginos/Neutralinos Charginos/Neutralinosdominates m 1/2 is the crucial parameter m 0 = 100 tan  = 5  < 0 m 1/2 (GeV) Cross-section (pb) ±0±0±0±0 squarks 00000000 ±±±±±±±± sleptons A 0 = 0; m 0 = 100; tan  = 5;  < 0

PASCOS January 2003Auguste Besson for D0 collab. 11 Cross-section (squarks) squark productions dependsquark productions depend ‘’only’’ on their mass tan  = 5;  < 0; A 0 = 0 Cross-section Squark-squark + Squark-antisquark Squarks dominate Cross-section (pb) squark mass (GeV) m 0 (GeV) m 1/2 (GeV)

PASCOS January 2003Auguste Besson for D0 collab. 12 squarks and gluinos Final StateFinal State >=2 jets + mET PRL 83, 4937 (1999) no EWSB Run I tan  = 2;  < 0; A 0 = 0 D0 Run II preliminary 2 jets mET D0 Run II preliminary  (jet1-jet2) - MC.  Data L ~ 6 pb -1 significant cuts: mET, pTjets scalar sum of ET acoplanarity

GMSB framework Run II preliminary study: di-photons + mET

PASCOS January 2003Auguste Besson for D0 collab. 14 GMSB Minimal Model of Gauge Mediation (MGM) 6 parameters :Minimal Model of Gauge Mediation (MGM) 6 parameters :  effective visible sector SUSY breaking parameter N number of messenger M m mass scale of messengers tan  ratio of v.e.v. of the 2 higgs doublets sign(  ) sign of mixing parameter of higgsinos C G ratio of the messenger sector SUSY breaking order parameter to the intrinsic SUSY breaking parameter –NLSP nature. either:  0 1, stau, slepton, squark, etc. –lifetime of NLSP –signature:  +mET; l  l  +mET ;     +mET, monojet Fermilab Run II workshop: Baer et al. hep-ph/ Baer et al. hep-ph/

PASCOS January 2003Auguste Besson for D0 collab. 15 Neutralino NLSPNeutralino NLSP Final state:Final state:  + mET + X N = 1; M m = 2   ; tan  =15;  > 0 BackgroundBackground W ,Wj,Zee,tt,WW,WZ,etc. Cuts: pT  > 20 GeV, track vetoCuts: pT  > 20 GeV, track veto  (Jet,mET)>0.5 M   GeV, vertex mET > 25 GeV di-photons + mET Run I D0. PRL 80, 3, 442 (1998) Run II preliminary: D0 Run II preliminary Expected Bkd 1.0  0.3 Data2 8.7  1.2 pb -1 - MC. + Data

R-Parity violated (RPV) consequences LSP decay LSP decay Run II preliminary study: like sign dileptons trileptons

PASCOS January 2003Auguste Besson for D0 collab. 17 SUSY potential:SUSY potential:  i,j,k = 1,2,3 (family indices)  = 45 new Yukawa couplings.  Lepton ( and ’) or Baryon ( ’’) number not conserved  define R-parity : discrete quantum number B= Baryon #, L=Lepton #, S=spin B= Baryon #, L=Lepton #, S=spin R p = +1  SM particle R p = +1  SM particle R p = -1  SUSY particle R p = -1  SUSY particle With R p = (-1) 3B+2S+L R-parity

PASCOS January 2003Auguste Besson for D0 collab. 18 R-p conserved:R-p conserved: -LSP stable and candidate for dark matter -Susy particles pair produced R-p violated: B or L not conservedR-p violated: B or L not conserved Lightest Susy Particle (LSP) decays eitherLightest Susy Particle (LSP) decays either - inside the detector (with or without a displaced vertex) -outside the detector Susy signature can be very differentSusy signature can be very different –Less missing Et –More leptons ( or ’) and jets ( ’ or ’’) Single Susy particle production is possibleSingle Susy particle production is possible -via ’ or TeVatron -cross-section  ( ’ ijk ) 2 q g q _ q ~ q ~ _ (+1) (-1) (+1) (-1) R-parity: consequences

PASCOS January 2003Auguste Besson for D0 collab. 19 RPV example: ’ 122 couplings ’ 122 L 1 Q 2 D 2 ’ 122 L 1 Q 2 D 2 Via ’ 122Via ’ 122 (+ cplx. conjugate) _ OR

PASCOS January 2003Auguste Besson for D0 collab. 20 ’ 122 : like sign dileptons ’ 122 : like sign dileptons Final stateFinal state 2 likesign e  + 4 jets Backgd: Drell-Yan, Zee, tt,Backgd: Drell-Yan, Zee, tt, e+efake, wrong sign assignment pT el > 15 GeVpT el > 15 GeV A 0 = 0 ;  < 0 ; tan  = 2 D0, Phys. Rev. Lett. 83, 4476 (99) Run I Run IIa simulation D0 Run II preliminary 2 like sign leptons + >= 1 jets SM backgd 0.1  0.1 Instrumental 2.8  1.3 Data2 D0 Run II preliminary jet multiplicity for dielectrons events m 0 (GeV) m 1/2 (GeV) L = 9.7  1.4 pb -1 - MC. + Data

PASCOS January 2003Auguste Besson for D0 collab. 21 coupling: trilepton channel coupling: trilepton channel Dominant coupling 121, 122 or 233Dominant coupling 121, 122 or 233 LSP  2 charged leptons + 1 LSP  2 charged leptons + 1 Backgd: Drell-Yan, tt, Z ,Backgd: Drell-Yan, tt, Z , misidentification of jets as electrons, cosmic  Final State :  eee,ee ,e ,  + missing ET e e e SM backgd 0.9  0.2 Instrumental 1  0.3 Data2 e e  SM backgd 0.13  0.08 e +  + e fake 0.6  0.2 e + e + cosmic   Data1 D0 Run II preliminary L = 5.2  0.8 pb -1

Large Extra Dimensions

PASCOS January 2003Auguste Besson for D0 collab. 23 Large extra dimensions Virtual gravitonVirtual graviton –Planck scale Ms final state final state ee, ,  ee, ,  Instrumental - Inst. + S.M. backgd + Data Run I Limit: (95% C.L.) Ms(GRW) > 1.2 TeV Run II preliminary: Ms(GRW) > 0.92 TeV L = 9.9 pb -1 diEM Mass (GeV) cos  * S.M. Data E.D. signal QCD

PASCOS January 2003Auguste Besson for D0 collab. 24 di-photon candidate D0 Run II preliminary ET 1 (GeV) ET 2 1111 2222 cos  * M  mET

PASCOS January 2003Auguste Besson for D0 collab. 25 Conclusion D0 detector: upgrade is a successD0 detector: upgrade is a success tremendous effort on calibration, comissioning, instrumental backgd, particle ID, etc. first new phenomena analysis underwayfirst new phenomena analysis underway –many exciting channels Luminosity large progress during the last monthsLuminosity large progress during the last months –now: ~ 50 pb -1 on tape –~ 200 pb -1 in summer 2003 –First Run II limits in the coming months. (better than the Run I results) Stay tuned !

Back up

PASCOS January 2003Auguste Besson for D0 collab. 27 SUSYSUSY - 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 modelsIn most of the models - SUSY particles are pair produced - The lightest SUSY particle (LSP) is stable and escape from detector. SUSY framework

PASCOS January 2003Auguste Besson for D0 collab. 28 2,3 and 4 body decays of stop

PASCOS January 2003Auguste Besson for D0 collab. 29 RPV Experimental constraints Indirect limits via low energy processesIndirect 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 GeV2  limits for m = 100 GeV (limits often linear in mass) Stronger limitsStronger limits on products of coupling - proton decay : ’’ 11k. ’ 11k < ’’ 11k. ’ 11k < Barger et al. Phys.Rev. D40 (89) Ledroit, Sajot GDR-S-008 (98) Allanach et al., PRD 60 (99) ~ u u d u dkdkdkdk ~ d _ e+e+ p

PASCOS January 2003Auguste Besson for D0 collab. 30 Resonant production : dimuons channel Dominant coupling ’ 211Dominant coupling ’ 211  resonant prod via RPV  Decay of LSP via RPV Backgd : tt, Z+2jets, WW+jetsBackgd : tt, Z+2jets, WW+jets Cuts : pT   20 GeV ; pT jets  20 GeVCuts : pT   20 GeV ; pT jets  20 GeV Scalar ET  50 GeV ;  R  jets  0.5 u 1o1o ~  LL ~ d _  u d Final State :  2  + 2 jets  u d d 1-1- ~ ++  ~ d _ l - l W - 1o1o ~ _ _

PASCOS January 2003Auguste Besson for D0 collab. 31 Dimuons in m 0 -m 1/2 plane Run I:Run I: L = 94  5 pb -1 Events observed = 5 Expected Background = 5.34  0.07 A 0 = 0 ;  < 0 ; tan  = % conf. level Run II: Run II: (Fast simulation) ’ 211 =0.05 ’ 211 =0.05 preliminary Déliot et al., EPJ C 19 (01) 155 A 0 = 0 ;  < 0 ; tan  = 2

PASCOS January 2003Auguste Besson for D0 collab. 32 m e1e2e3 = 85.2 GeV/c 2 ME T =10.7 GeV m e2e3 = 63.5 m e1e3 = 10.8 m e1e2 = 55.7 e3e2e1 E T = 13.2 GeV p T = 15.1 GeV  = 1.06  = 5.72 Charge = -1 E T = 13.9 GeV p T = 10.9 GeV  =  = 2.80 Charge = +1 E T = 17.9 GeV p T = 0.52 GeV  = 0.43  = 5.42 Charge = +1 D  Run 2 Preliminary Electrons Trilepton events are classical SUSY signature Electron eee candidate event

PASCOS January 2003Auguste Besson for D0 collab. 33 ME T =31.8 GeV m  = 41.5 GeV/c 2 2222 1111e p T = 9.82 GeV  =  = 2.88 Charge = 1 p T = 28.2 GeV  =  = 6.20 Charge = -1 E T = 19.2 GeV  = 0.40  = 0.63 No track match Muon Electron ME T Muon system Muon e  candidate event D  Run 2 Preliminary D0 Run II preliminary

PASCOS January 2003Auguste Besson for D0 collab. 34 ee  candidate event D0 Run II preliminary