We reviewed CDF and D0 searches for R-parity violation supersymmetry in
leptons involved final states using up to 344+-21 pb-1 Tevatron Run II data of
ppbar collisions at sqrt{s} = 1.96 TeV. All the results were in good agreement
with the standard model expectations. No evidence of new physics was observed.
However, owing to the improvement on detectors, energy and luminosity from Run
I to Run II, the limits for the existence of R-parity violation supersymmetry
have been greatly advanced.Comment: EPS HEP2005 conference proceeding

/Wisconsin U., Madison

Chuang, Shan-Huei

English

arXiv

We reviewed CDF and D0 searches for R-parity violation supersymmetry in leptons involved final states using up to 344 {+-} 21 pb{sup -1} Tevatron Run II data of p{bar p} collisions at {radical}s = 1.96 TeV. All the results were in good agreement with the Standard Model expectations. No evidence of new physics was observed. However, owing to the improvement on detectors, energy and luminosity from Run I to Run II, the limits for the existence of R-parity violation supersymmetry have been greatly advanced

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Search for RPV Scalar Leptons at TevatronShan-Huei Chuang  †University of Wisconsin - Madison, USAE-mail: schuang@fnal.govWe reviewed CDF and DO searches for R-parity violation supersymmetry in leptons involvedfinal states using up to 344  21 pb  1 Tevatron Run II data of pp̄ collisions at  s  1  96 TeV. Allthe results were in good agreement with the Standard Model expectations. No evidence of newphysics was observed. However, owing to the improvement on detectors, energy and luminosityfrom Run I to Run II, the limits for the existence of R-parity violation supersymmetry have beengreatly advanced.International Europhysics Conference on High Energy PhysicsLisboa, PortugalJuly 21st - 27th 2005Speaker.†On Behalf of the CDF and D O Collaborationsc	Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/FERMILAB-CONF-05-548-ESearch for RPV Scalar Leptons at Tevatron Shan-Huei Chuang1. IntroductionAlthough the Standard Model (SM) has been remarkably successful in describing presentlyknown phenomena there are arguments to consider it as a low-energy effective, hence the con-struction of its extensions to high energies. Supersymmetry (SUSY) is the most appealing SMextension. Mainly motivated by the cancellation of quadratic divergences in scalar boson massloop corrections, SUSY postulates such a symmetry that every fermion has a bosonic superpartnerand every boson has a fermionic superpartner [1]. The R parity is defined as R    1  3B  L  2J .R  1 for the Standard Modelmost SUSY models. SUSY by itself does not impose R parity conservation. In a minimalR parity violation ( 	R ) SUSY model the gauge invariance of the minimal supersymmetric extensionof Standard Model (MSSM) allows the following additional Yukawa couplings in the Lagrangian: 	R   λi jkLiL jĒk  λ i jkLiQ jD̄k  λ  i jkD̄iD̄ jŪk  (1.1)where i  j  k are family indices [2]. The λ and λ  terms violate lepton number (LNV) and theλ   terms violate baryon number (BNV). Proton decay via squark d̃2 forbids the co-existence ofLNV and BNV but not either one. In analogy to the standard Yukawa couplings one expects ahierarchical structure among the 	R couplings and hence the lightest superparticle (LSP) to decaydominantly into one of the 45 	R channels.2. Search for R-parity Violation Decay of SneutrinoCDF searched in 344  21 pb  1 Run II data for high mass resonance decaying into an electronplus a muon and interpreted the results in the context of 	Rλ 311 production and λ132 decay of dd̄ ν̃τ  eµ [3]. The high pt eµ signature let in little SM backgrounds. The search used high pt lepton)2 (GeV/cµeM50 100 150 200 250 300 3502Events/ 5 GeV/c-210-110110210Data µe→ν∼2Mass = 200 GeV/c = 0.05132λ=0.16311’λτ τ →Z ttDibosonFakes-1CDF Run 2 Preliminary, 344 pbFigure 1: The mass spectrum of data observa-tion vs SM expectation, showing good agree-ment. The ν̃τ signal contribution is hypothetical.triggers and selected events with Ne  1 and Nµ 1, requiring each lepton to have pt  20 GeV andbe isolated and each lepton pair to be close atbeam axis with ∆z0  5 cm and have oppositesigns of charge. Signal and SM backgrounds (ex-cept QCD) were modeled using PYTHIA (jet data)with the h0SM particle being a functional substitutefor ν̃τ . See Figure 1. Uncertainties on acceptanceincluded 9.2% due to MC generator, 3.2% due tomomentum resolution and 2.4% due to parton dis-tribution function; on backgrounds the largest wasthe 16% from QCD. Observing no excess in data95% CL limits of ν̃τ production cross-section aswell as of λ 311 and of λ132 were set. See Figure 2.3. Search for RProduction and Decay of Slepton via the LQD̄ Coupling λ 211D 	O searched in 154  10 pb  1 Run II data for the resonant production of µ̃ which leads toa final state with two muons and two jets and the advantage of all the masses reconstructable,2Search for RPV Scalar Leptons at Tevatron Shan-Huei Chuang)2 (TeV/cµeM0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45132λ0.0050.010.0150.020.0250.030.0350.040.0450.05 :311’λ0.1600.1280.0960.0640.032-1CDF Run 2 Preliminary, 344 pb)2 (TeV/cµeM0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45311’λ0.020.040.060.080.10.120.140.16 :132λ0.0500.0400.0300.0200.010-1CDF Run 2 Preliminary, 344 pbFigure 2: The upper limits of λ132 for fixed λ  311 (left) and of λ  311 for fixed λ132 (right) as a function of mν̃τ .Figure 3 (left), assuming λ 211 is the dominant 	Rcoupling [4]. The search used dimuon triggers andselected events with SB-optimized mass dependent cuts: 	Et  60 GeV, 2 isolated muons withpt  µ1  µ2   21 	 25  0 	 1875  mµ̃  mχ̃01   10  GeV and pt µ1  pt µ2  60 GeV, 2 jets in η   2 andEt  j1  j2   25  15  GeV, mχ̃01 MC40  mχ̃01  mχ̃01 MC  20 GeV, mµ̃ MCmµ̃   0 	 2mµ̃ MC, rejectingZ with mµµ  91   mχ̃019  5 GeV and suppressing QCD by requiring large angle between anytwo final-state objects. Signal was modeled with SUSYGEN, scanning over 25 {m µ̃  mχ̃01 } pointswith λ 211  0 	 07  A0  0  tan β  2 and the higgsino mass mixing parameter µ  0. The only non-negligible background Z+2 j was modeled with PYTHIA. By far the largest uncertainty  30% wasdue to jet energy scale. Reasonable agreement was found for all points, e.g. expected : observed 1 	 1  0 	 4 : 2 events. Observing no excess in data 95% CL limits of µ̃ production cross-sectionand of λ 211 were set, as shown in Figure 3 (middle and right).ud-µ∼-µ01χ∼-µ+µ∼ud•211’λ• 211’λSlepton mass [GeV]160 180 200 220 240 260 280 300 320 340 [pb]σlimit / 0246810121416ExcludedRun I=0.07211’λ=75 GeV, 10χ∼,  σ=75 GeV10χ∼Limit 95%CL, D0 RunII preliminary = 0.07  211’λ   Limit for a fixed neutralino mass = 75GeV and Slepton mass [GeV]160 180 200 220 240 260 280 300 320 340211’λ coupling DLQ00.050.10.150.20.250.30.350.4Excluded=75 GeV10χ∼Limit 95%CL, D0 Run I)ν µ →π(Γ)/ν e →π(ΓD0 RunII preliminary   Limit for a fixed neutralino mass = 75GeV    Figure 3: Feynman diagram forR µ̃ production and leptonic χ̃01 decay (hadronic not drawn) via λ  211. Theµ or quark directly from the χ̃01 decay is expected to have low pt since its sparticle sister is highly virtual(left). The µ̃ production cross-section limits (middle) and the λ  211 limits (right) as a function of mµ̃ .4. Search for RPV Decay of Chargino/Neutralino into  3 Lepton Final StateD 	O has searched for 	R leptonic decays of χ̃01 via λ121, λ122, λ133 into final states that containee  , µµ  , eeτh where   e  µ  separately [5, 6, 7]. The searches commonly considered the sce-3Search for RPV Scalar Leptons at Tevatron Shan-Huei Chuangnario in which, given the 	Rcouplings have been set significantly smaller than the gauge couplingsby low-energy experiments [8], most SUSY processes conserve R parity and only LSP can 	R -decayinto SM particles. Sparticles can only be pair produced at Tevatron [1]. In the processes of pp̄ SP-pair ...  LSP-pair ...  R    ν   ν ... at least 4 leptons are in final state. Event selections went0 5 10 15 20 25 30 35 40 45 5010102103 (opposite sign) τ + reco  µiso ττMC Z  (likesign)τ + reco µiso µµMC Z Ttau pnumber of events Run II Preliminary∅DFigure 4: The pt spectrum of hadronically de-cayed tauon (τh) candidates after neural networkidentification.commonly as follow: isolated high or medium ptdielectron or dimuon with invariant mass outside ϒand Z regions, an additional low pt lepton (see Fig-ure 4), and significant 	Et presence to reduce QCDbackground; the 4th lepton was not required to in-crease signal acceptances. Signals were modeledwith SUSYGEN, scanning over 140  m1  2  280GeV. SM backgrounds (except QCD), of whichthe largest was Drell-Yan, were estimated withPYTHIA (jet data). Uncertainties on acceptanceswere driven by the 6% on luminosities; on back-grounds 60% of total were from DY and QCD.Results and related SUSY parameters are summa-rized in Table 1.int (pb  1) λ constraint tanβ m0 Nexpected : Nobserved mµ  0χ̃01mµ  0χ̃ 1mµ  0χ̃01mµ  0χ̃ 1ee  238  16 λ121=0  010 5 250 0  45  0  43 : 0 95 181 97 183µµ  160  10 λ122=0  001 5 250 0  63  1  93 : 2 84 160 90 165eeτh 199  13 λ133=0  003 10 80 1  04  1  42 : 0 66 118Table 1: Summary of theRSUSY trilepton searches, all in good agreement with the SM expectations.A0  0. The 95% CL lower mχ̃01 or mχ̃ 1 limits (GeV) for µ  0 or µ  0 are shown in the last four columns.5. ConclusionAs CDF and D 	O have searched so far there is no evidence of 	RSUSY yet. The limits ofR-parity violation supersymmetry have been either newly set or pushed way further.References[1] A Supersymmetry Primer, Stephen P. Martin, hep-ph/9709356, April 7 1999.[2] S.Dimopoulos & L.Hall, Phys.Lett.B207:210, 1988. H.Dreiner & G.Ross, Nucl.Phys.B365:597, 1991.[3] A Search for RPV Sneutrino Decay to eµ , CDF conference note 7616, 2005.[4] Search for Resonant Slepton Production via the LQD̄ Coupling λ  211, D0note4535-CONF, 2004.[5] Search for SUSY with RPV in the ee  Final State, D0note4522-CONF, 2004.[6] Search for SUSY with RPV in the µµ  Final State, D0note4490-CONF, 2004.[7] Search for SUSY with RPV in the eeτ Final State, D0note4595-CONF, 2005.[8] V.Barger et al., Phys.Rev.D40:2987’89, Phys.Rev.D50:4299’94. X.Tata et al., Phys.Rev.D51:2180’95.4

Search for RPV scalar leptons at Tevatron

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Search for RPV Scalar Leptons at Tevatron

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