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Beyond the SM model Experimental Results From LEP

Beyond the SM model Experimental Results From LEP. Corinne Goy On behalf the 4 Collaborations. H. See other talks…. Standard Model: SU(3) c SU(2) L U(1) y. EWSB. Extended Higgs sector. (. ) L. (. ) L. (. ) L. Super Sym. u d. c s. t b. W, Z, . L:.   . ) L. ) L. (.

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Beyond the SM model Experimental Results From LEP

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  1. Beyond the SM modelExperimental Results From LEP Corinne Goy On behalf the 4 Collaborations

  2. H See other talks… Standard Model: SU(3)cSU(2)LU(1)y EWSB Extended Higgs sector ( )L ( )L ( )L SuperSym u d c s t b W, Z,  L:  )L )L ( ( ( )L e e   • SO(10), E6, … : • New Fermions • Z’ R: uR,dR ,cR ,sR ,tR ,bR, eR,R ,R,eR,R,R • Compositeness: • Leptoquark • Excited fermions • Technicolor: • Technipions • Technirho ? • Extra dimensions: • Low Scale Gravity • Non commutative Geometry Unification of Everything

  3. LEP2 S max= 209 GeV Lum/exp = 700 pb-1 • Limit of sensitivity for direct searches: 0.1 pb

  4. Direct Searches @ LEP • Pair production : sensitivity up to S/2  105 GeV • Single production : sensitivity up to S  209 GeV • coupling vs. mass • Clean environment • Particle Id • b tagging, leptons, multi-jet • Tightness of detectors : • final states with missing energy :  • single  topology C.G Moriond QCD 2003

  5. Indirect Searches @ LEP • Sensitivity largely above S by looking at deviation from expectations of : Cross-sections, Asymmetries, Branching ratios, Couplings, etc • Luminosity of ~ 700 pb-1 /experiment • e+e-  qq :1%,  : 1.6 % • Theoretical precision : 1/3 of exp. error for most channels (Yellow Report CERN 2000-009, S. Jadach et al. ) Z SMqq = 1.63  C.G Moriond QCD 2003

  6. New Families : L0,L±,Nl,b’ • Heavy Isosinglet with coupling to the Z through light neutrino mixing : Ne • Heavy Isodoublet : L, L0 • Sequential/Vector /Mirror • Heavy Quarks (Sequential) Direct Search only : Favored decay: C.G Moriond QCD 2003

  7. New Families : Leptons All Limits close to the kinematical limit of 105 GeV C.G Moriond QCD 2003

  8. New Families : Quark (SM) e+ e- b’b’ bbZZ ννqqbb ννllbb Likelihood analysis for Mb’ = 100 GeV (kin. limit) ( For information CDF : ) C.G Moriond QCD 2003

  9. Extra Gauge Bosons : Z’ Indirect search with 2 fermions final states: e+e-  ff • Many extensions of SM predict additional Neutral and Charged gauge bosons: E6, L-R (× SU(2)R), Y (× U(1) ) • ZZ’ reduced to few mrad with Z peak data  set to 0 gL= gR C.G Moriond QCD 2003

  10. Excited Leptons • The existence of 3 at least families gives strong motivation for a fermionic substructure • Effective Lagrangian : • Transitions from l* to l are caracterised by a scale  and relative couplings f’/f with respect to the structure constants of SU(2)  U(1) • Hypo : f=f’ (* forbidden) or f=-f’ (l*  l forbidden)  f/ and Ml* Pair production All families Single production All families Indirect signature First family only C.G Moriond QCD 2003

  11. Excited Charged Leptons new limits for the whole data set but not combined so far. f/f’ independent limits (prel.): Ml* > 96.5/96.6/95.6 GeV Excited Neutrinos not combined so far. f/f’ independent limits (prel): M* > 101.5/101.4/91.3 GeV

  12. Leptoquarks • Effective Lagrangian that satisfies the SM framework (Buchmuller,Ruck,Wyler): • 10 species SI or VI (labeled according to spin, isospin, hypercharge) • Couplings : • to either L or R leptons exclusively : LQIR/L (Exp. limit R L=0 ) • to generations of leptons and quarks : lq (Exp. limit 12 11 , 11 21 = 0) S/2 Production independent of couplings Sensitivity to final states with  TeV Sensitivity to 11,,12 ,13 S/2 Sensitivity to 11 C.G Moriond QCD 2003

  13. An Example : S0L and 11(e-u,e-d) LEP direct search limit, within Tevatron limits in most of the cases (except with final states including ) C.G Moriond QCD 2003

  14. Limits on  vs. MLQfrom the combined LEP measurement Coupling to e-b using Rb and Afb-b excluded 0.3

  15. Technicolor Models • Technicolor models may provide an alternative mechanism to EWSB, where the symmetry is dynamically broken due to the existence of an additional QCD -like interaction (+ extension to minimal scenario) : • Technicolor Straw Man Model (TCSM) leaves few free parameters: • At LEP, sensitivity to the lowest mass bound states: • scalar Technipions : T , T0 • vector TechniRho : T0 • Transitions would be mediated by a TechniRho ( a la VDM) • e+e-  qq • e+e-  WW • e+e-  W T • e+e-  T +T- • e+e-   T0  Limits in the plane MT vs MT0 } indirect } Direct production of T  bb, bc C.G Moriond QCD 2003

  16. Technicolor Models Limits, but parameters dependant (MV and charge of the techniquarks) Combination of direct + indirect searches. Parameters independent limits in TCSM (ND 2) : MT > 79.8 GeV MT > 206.7 GeV (or MT < 90 GeV) C.G Moriond QCD 2003

  17. Single Top Production : • Proceeds via loop diagrams with cross-section < 10-9 fb • But New Physics could lead to enhancement. • Parametrised in anomalous vertices  , Z LEP improved the exclusion plotand L = 675 pb-1,S = 189 GeV,  < 0.11 pb L = 484 pb-1,S = 207 GeV,  < 0.17 pb C.G Moriond QCD 2003

  18. Extra-Dimensions • In ADD –like models of Large Extra Spatial dimensions: • An effective Planck scale MD which could be as low as 1 TeV. • The graviton is seen in our world as a superposition of massive states (G KK tower) • At LEP , GKK couples to the energy-tensor, therefore modifies unambiguously • cross-sections and asymmetries of SM model processes : • direct production : • e+e-G, ZG • depends both on MD and n extra dimensions.  : Intf sign MS cut-off ( ~ MD) C.G Moriond QCD 2003

  19. GKK Indirect Signature Ms > 1.20 TeV ( Pos. Intf) Ms > 1.09 TeV ( Neg. Intf) From the measured differential cross-section, a fit to (/Ms4) can be performed C.G Moriond QCD 2003

  20. GKK Direct Production Single  topology C.G Moriond QCD 2003

  21. Non Commutative Geometry • Select a preferred direction in space CE0, but unpredicted • NC : energy scale at which the N.C effects are visible • No full non-commutative SM exists • only Non-Commutative QED is consistently defined : NCQED LEP • NCQED depends upon: • polar angle  • azimuthal , time • orientation of the detector wrt to CE0 (,) • NC Earth rotation axis Position of Experiment (Local coordinates : , fixed,  time dependant (phase)) Space (Fixed coordinates at least for the 4 years of data taking considered) C.G Moriond QCD 2003

  22. SM Integrated over  and averaged over time. Integrated over  and averaged over time  Improved limits for some values of  using the distribution in  NC > 141 GeV independent of  and 

  23. Contact Interactions (in colors) Specific for LEP: eeee, eell, eebb, eecc C.G Moriond QCD 2003

  24. Contact Interactions (in numbers) 8 models × 9 channels × 2 limits = 144 numbers are available from LEP I spare you them all !!!! C.G Moriond QCD 2003

  25. Contact Term :  final states • From the transition e+e- From the constraint  < ~0.3:  > ~ 1 TeV NB: other parametrisation • 3 cases studied : • only electron neutrino • only tau neutrino • flavour changing neutral current Coloured region is not excluded C.G Moriond QCD 2003

  26. Triple Gauge Couplings g1z (=1)  (=1) (=0) • Due to the non abelian structure of SU(2), WWZ and WW couplings exist at tree level (and are measurable at LEP) : test of the group structure. • Possible deviation from New Physics at few 10-3 from MSSM , SO(10) Combined measurement at the % level Good agreement with SM predictions C.G Moriond QCD 2003

  27. Conclusions • We didn’t find anything where we looked! • Open minded searches : • lots of topologies looked for within or without the support of a model. • indirect constraints on several models from the precision LEP2 measurements. • Few LEP combinations to complete • Excited Leptons (charged and neutral) • Technicolor • Direct GKK Search • Era of Extra Dimensions opened • Kaluza-Klein towers in ADD models. • Non Commutative QED. C.G Moriond QCD 2003

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