Search for R-parity Violation at D

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Search for R-parity Violation at DØ
on behalf of the DØ collaboration
Frédéric Déliot CEA-Saclay, France
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Search for R-parity Violation at DØ

• introduction
• the TeVatron and the DØ experiment
• R-parity violation
• pair production R?p LSP decay
• dilepton signal via ? ?
• trilepton signal via ?
• top decays via ? or ? ?
• sparticule resonant production
• resonant slepton production ?
• resonant stop production ?

? new results included
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The TeVatron
Run duration center of mass energy integrated luminosity
RunI 1992-1996 1.8 TeV 0.13 fb-1
RunIIa 2001-2003 2.TeV 2 fb-1
RunIIb 2004-2007 2.TeV 15 fb-1

• RunII 2 new accelerators
• (3.3 km ring)
• Main injector (injector to the TeVatron, p
  production)
• recycler (p recycling ring)

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The DØ Detector

• DØ upgrade for RunII
• new tracking system (Si tracker, fiber tracker)
• central solenoid
• preshower
• new forward muon system

• DØ in RunI
• central detector (drift chambers, transition
  radiation detector)
• no central magnetic field

• compact and hermetic Ar-U calorimeter
• muon system with iron toroid

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R-parity
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R-parity Violation

• experimental consequences of R?p
• B and/or L violation
• LSP can decay with or without displaced vertices
• sparticules can be produced resonantly
• usual search hypothesis
• mSUGRA with ?01 as LSP and R?p
• similarly to Yukawa couplings hierarchy, only
  one R?p coupling dominates
• if R?p coupling large enough, resonant
  production
• otherwise pair production R?p does not affect
  branching ratios except for LSP decay

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Limits on R-parity Violation Couplings
Dreiner, hep-ph/9707435 Ledroit, Sajot, GDR-S-008

• indirect limits via low energy processes
• (assuming a single dominant R?p)
• neutrinoless double-beta decay
• charged-current universality constraints
• e-?-? universality
• ??-e scattering
• AFB
• atomic parity violation

2 ? limits for m 100GeV
ijk ?ijk ijk ?'ijk ijk ?'ijk ijk ?'ijk ijk ?"ijk
121 0.05 111 5.2 10-4 211 0.06 311 0.12 112 10-6
122 0.05 112 0.02 212 0.06 312 0.12 113 10-5
123 0.05 113 0.02 213 0.06 313 0.12 123 1.25
131 0.07 121 0.04 221 0.18 321 0.52 212 1.25
132 0.07 122 0.04 222 0.18 322 0.52 213 1.25
133 0.006 123 0.04 223 0.18 323 0.52 223 1.25
231 0.07 131 0.04 231 0.18 331 0.58 312 0.50
232 0.07 132 0.28 232 0.45 332 0.58 313 0.50
233 0.07 133 1.4 10-3 233 0.15 333 0.58 323 0.50
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Pair Production Dielectron Channel
DØ, PRL 83 (99) 4476

• All pair production processes considered
• dominant coupling one of the six ?1jk (j1,2
  k1,2,3)
• LSP decay to 1 electron and 2 jets (close to its
  production)
• channel ? 2 electrons ? 4 jets
• background Drell Yann, tt, Z????ee,
  misidentification of jets as electrons

RunI Results Lint 99 ? 4.4 pb-1 Events
observed 2 Expected Bkg 1.8 ? 0.2 ? 0.3
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?1jk Dielectron Channel in Run I
A00, ?lt 0, tan ? 2
A00, ?lt 0, tan ? 6
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Dielectron Channel in RunII
A00, ?lt 0, tan ? 2
Lint 2 fb-1 , ?s2 TeV Scenario I
extrapolation from RunI Scenario II electrons
misidentification reduced by a factor 2 due to
central magnetic field
Mg ? 500 GeV Mq ? 400 GeV
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Pair Production Dimuon Channel
DØ, preliminary

• All pair production processes considered
• dominant coupling
• same analysis as previously with a dominant
  ?2jk
• channel ? 2 muons ? 4 jets
• background Drell Yann, tt, Z???jets, Z??????,
  WW???

Run I Results Lint 77.5 ? 4 pb-1 Events
observed 0 Expected Bkg 0.18 ? 0.031 ? 0.02
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?2jk Dimuon Channel
RunII, 2 fb-1
RunI
A00, ?lt 0, tan ? 2
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Pair Production Multilepton Channel
DØ, PRL 80 (98) 1592

• dominant coupling ?121 ,?122 or ?233
• LSP decay to 2 charged leptons and a neutrino
• channel reinterpretation of search for ?1?
  ?20 production
• 4 different final states ? eee, ? ee?, ? e??, ?
  ??? E?t
• background Drell Yann, tt, Z????ee,
  misidentification of jets as electrons

Run I Results
?
eee ee? e?? ???
Lint 97.8 ?5.2 97.8 ?5.2 93.1 ?4.9 78.3 ?4.1
Obs evts 0 0 0 0
Bkg 0.34 ?0.07 0.61 ?0.36 0.11 ?0.04 0.20 ?0.04
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?ijk Multilepton Channel in Run I
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Top Decay via R?p
Abraham et al., PRD 63 (01) 34011

• dominant coupling ?331
• pp ? tt with one t ? bd?01 (?01 decays
  outside the detector) and t ? Wb ? l?b
• channel 1 lepton, 3 jets with 2 b-tagged E?t
• background tt, Wbbj

RunII ?s2 TeV, Lint 2 fb-1
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Top Decay via R?p
Han et al., PLB 476 (00) 79

• dominant coupling ?333
• pp ? tt with one t ? ?b?01 (?01 decays in or
  outside the detector)
• channel same signal as H? ?b? detection
  optimized for SM tt analysis ? disappearance
  experiment
• background tt, Wjets

long lived LSP
Indirect 2 ? limit for m 100 GeV ?333 0.58
for M? 70 GeV, ?333 lt 0.94 at 95 CL RunII
(2fb-1) ?333 lt 0.38
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Resonant Production

• at hadronic colliders, resonant production via
  ? or ?
• via ? resonant slepton production (?,?)
• via ? resonant squark production (t)
• generally assumed that those sparticles decay
  via Rp conserved couplings
• cascade to LSP which decays into the detector or
  outside the detector depending on the dominant
  coupling considered

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Resonant Slepton Production
Déliot et al., EPJ C 19 (01) 155

• dominant coupling ?
• chargino or neutralino singly produced
• 4 possible channels

?(?) in pb
?2110.09, ?lt 0, tan ? 2
?(?) in pb
m0
m0
M2
M2
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Resonant Production Dimuon Channel
DØ, preliminary

• dominant coupling ?211
• resonant ? or ?? production
• channel ? 2 muons ? 2 jets
• background tt, Z2jets, WWjets

Run I Results Lint 94 ? 5 pb-1 Events
observed 5 Expected Bkg 5.34 ? 0.07
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Resonant ?211 Dimuon Channel in Run I
A00, ?lt 0, tan ? 2
?s1.8 TeV Exclusion contours at 95 CL down to
?211 0.07 and m0? 200 GeV m1/2 ? 220 GeV
Indirect 2 ? limit for m 100 GeV ?211 0.06
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Resonant ?211 in RunII Trilepton Channel
Déliot et al., EPJ C 19 (01) 155
search for trilepton channel via resonant
sneutrino production
?s2 TeV, A00, ?lt 0, tan ? 1.5
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RunII Trilepton Channel Mass Reconstruction

• allow mass reconstructions
• simulation M?0177.7 GeV, M?1158.3 GeV,
  M?236 GeV
• 2 jets and softer muon M?0171 GeV (?9)

Lint 10fb-1 ?211 0.09
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Resonant ?211 in RunII Dimuon Channel
search for dimuon channel via resonant smuon
production
Lint 2fb-1, ?211 0.05 A00, ?lt 0, tan ? 1.5
Lint 10fb-1 ?211 0.05
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Resonant Squark Production
Berger et al., PRD 63 (01) 115001

• dominant coupling ?3jk
• resonant stop production, decay to b ?1 and
  ?01 decays outside the detector
• channel 1 b-tagged jet, 1 e or 1 ? E?t
• background Wc, Wj with c or j that mimics a b,
  Wbb, Wcc, single top via Wg

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Resonant ?3jk in Run I
?s1.8 TeV, Lint 110pb-1
Indirect 2 ? limit for m 100 GeV ?312
0.50
for Mt 255 GeV, ?312 lt 0.08 at 95 CL
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Resonant ?3jk in RunII
?s2 TeV, Lint 2 fb-1
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Conclusion

• DØ searches for R-parity violation in RunI
• large number of R?p couplings explored
• ? No sign of R?p SUSY found
• DØ RunII will provide a wide range of improved
  coupling limits and a great discovery potential
• ? 20 ? more luminosity (2003)
• 10 more energy
• improved detectors
• ? large increase on R?p coupling and mass
  sensitivity