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Search for Extra-Dimensions at pp and ep Colliders

Search for Extra-Dimensions at pp and ep Colliders. _. Eric Kajfasz, CPPM/D0 kajfasz@cppm.in2p3.gov for the CDF, D0, H1 and Zeus collaborations. Extra Dimensions: Outline. Extra Dimension Models and Signatures studied at CDF & D0 Run II, H1 and ZEUS

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Search for Extra-Dimensions at pp and ep Colliders

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  1. Search for Extra-Dimensionsat pp and ep Colliders _ Eric Kajfasz, CPPM/D0 kajfasz@cppm.in2p3.gov for the CDF, D0, H1 and Zeus collaborations Eric Kajfasz, CPPM/D0

  2. Extra Dimensions: Outline • Extra Dimension Models and Signatures studied at CDF & D0 Run II, H1 and ZEUS • Preliminary results on virtual graviton/gauge boson exchange and direct graviton emission • Summary and Conclusions • Why ED? • come “naturally” with string theory • provide mechanism to explain why MEW << MPL • ... Eric Kajfasz, CPPM/D0

  3. Extra Dimensions: Models Explored focus on n extra dims in models where SM fermions live on a D3-brane: • Large Extra Dimensions (LED) Arkani-Hamed,Dimopoulos,Dvali Phys Lett B429 (98) • MPL ~ 1019GeV • n >= 2 compact and flat - MS : string/fundamental scale M2PL ~ Rn MSn+2 => MS can be lowered to TeV scale • gravitons propagate in the bulk => Kaluza-Klein tower G(k) • can’t resolve successive modes (0.01eV:n=2; 1MeV:n=3; 100MeV:n=6) => expect: • virtual exchange of graviton KK modes • real graviton emission • TeV-1 Extra Dimension (TeV-1) Dienes,Dudas,Gherghetta Nucl Phys B537 (99) • MC : compactification scale (~ TeV) • gauge fields can propagate in the bulk => KK towers of gauge bosons • modes with nearly equal energy spacing ~TeV • lower GUT scale by changing running of the couplings => expect: • resonances at high energies (LHC ...) • virtual exchange (Hera, Tevatron) Eric Kajfasz, CPPM/D0

  4. Extra Dimensions: Models Explored ... y=0 y=Rp y • Warped Extra Dimension (RS) Randull,Sundrum Phys Rev Lett 83 (99) • ED of size R, highly curved, compactified on S1/Z2 orbifold: y = Rf. • Zero mode graviton G(0) localized at the Planck-brane (y = 0) • SM fields localized on TeV-brane (y = Rp) • metric: ds2 = e-2kRfhmndxmdxn – R2df2k: curvature scalefor kR ~ 11-12, Lp = MPLe-kRp~ TeV • consistency => 0.01 < k/MPL < 0.1 • Gravitons propagate in the bulk => KK tower G(n) of modes of mass mn = xnke-kRp(xn: 1st Bessel func. zeros i.e. 3.83, 7.02, 10.17, ...)=> well separated modes • Lp = m1MPL/(kx1) => model characterized by m1 and k/MPL • => Look for first graviton resonance Eric Kajfasz, CPPM/D0

  5. Extra Dimensions: Topologies Explored KK ee, mm, gg q _ _ q q KK e e p jet Exchange Virtual Gravitons (LED,TeV-1,RS) Tevatron Hera G jet(s) + MET g + MET Emission of Real Gravitons (LED) q g(jet),g Tevatron Eric Kajfasz, CPPM/D0

  6. Large Extra DimensionsVirtual Graviton Exchange _ _ _ f f f G(n) g/Z G(n) f f f G(n) G(n) G(n) dilepton channel (Tevatron) SM SM diphoton channel (Tevatron) DIS channel (Hera) SM Eric Kajfasz, CPPM/D0

  7. Large Extra DimensionsVirtual Graviton Exchange s = sSM + hGsint + hG2sKK • Effect of ED parameterized by a single variable: • different formalisms have different definitions of MS: • Hewett: (Hewett, Phys Rev Lett 82, 4765 (99) )F = 2l/p with l = ± 1 • GRW: (Giudice, Rattazzi, Wells, hep-ph/9811291)F = 1 • HLZ: (Han, Lykken, Zhang, hep-ph/9811350)F = log(MS2/s) for n = 2F = 2/(n-2) for n > 2 hG= F/ MS4 Eric Kajfasz, CPPM/D0

  8. Large Extra Dimensions: Virtual Graviton Exchange ee • 2 isolated e’s, ET> 25 GeV • e’s coming from luminous region • MET significance cut • eCC = 92.4 ± 0.4% eCP = 79.2 ± 0.5% • for Mee > 350 GeV: Nexp = 4.6, Nobs = 8 • Mee distrib. used in binned likelihood => Limits on hG=l/MS4 CC+CP 95% CL limits on MS (TeV) Mee C(entral): |h|<1 P(lug) : 1<|h|<3 Eric Kajfasz, CPPM/D0

  9. Large Extra Dimensions: Virtual Graviton Exchange diEM • diEM = combine ee and gg • 2 EM objects, ET > 25 GeVwith track isolation • overall ID efficiency: 85 ± 1 % • for MdiEM > 350 GeV:Nexp = 9.7 (1.6 QCD), Nobs = 8 • Systematics: ~ 12% 200pb-1 CC-CC + CC-EC signal for hG = 0.6 D-Y+ direct gg + QCD QCD CC-CC + CC-EC CC: |h|<1.1 EC: 1.5<|h|<2.4 Eric Kajfasz, CPPM/D0

  10. Large Extra Dimensions: Virtual Graviton Exchange Run II Run I+II diEM • Data agree with SM predictions => • MdiEM vs|cosq*| distrib. usedin 2D Binned Likelihood • =>Set limits on hG alone orin combination with Run I results • => give 95% CL limits on MS (TeV) • Most stringent constraints on LED for n > 2 to date among all experiments. 200pb-1 Eric Kajfasz, CPPM/D0

  11. Large Extra Dimensions: Virtual Graviton Exchange mm • 2 m’s with PT > 15 GeV • isolated, |h|<2.0 • cosmic veto • Mmm > 50 GeV • for Mmm > 300 GeV:Nexp = 6.4 and Nobs = 5 • Systematics: ~ 13% D0 RunII Preliminary Mmmvs|cosq*| distr. used in 2D Binned Likelihood => Set limits on hG => 95% CL limits on MS (TeV) 250pb-1 Eric Kajfasz, CPPM/D0

  12. Large Extra Dimensions:HERA Virtual Graviton Exchange G(k) Virtual exchange in t-channel interferes with Deep Inelastic Scattering (DIS) Small contribution ~ O(1%) from eg -> eg G(k) exchange affects the Q2 distribution at high Q2 Compare ds/dQ2 to what is expected from SM Q2 = (k-k’)2 = -q2 ,KK Eric Kajfasz, CPPM/D0

  13. Large Extra Dimensions: Virtual Graviton Exchange DIS c2 fit of ds/dQ2 no deviation from SM => Set limits on hG => 95% CL limits on MS (TeV) Hewett formalism Eric Kajfasz, CPPM/D0

  14. Large Extra Dimensions: Virtual Graviton Exchange DIS ds/dQ2 used in binned likelihood => Set limits on hG => 95% CL limits on MS (TeV) • Hewett formalism: • l = - 1 : MS > 0.79 TeV • = + 1 : MS > 0.78 TeV Eric Kajfasz, CPPM/D0

  15. Large Extra Dimensions:Direct Graviton Emission MS (K = 1) n jet(s)+MET • Graviton produced along with a jet disappears in the bulk, undetected => mono-jet like topology with high MET • Nexp = 100.2 ± 6.3 (stat) ± 7.5 (theo) + 50 - 30 (JES) • Nobs = 63 (~ 5% efficiency) • Final Selection: • MET > 150 GeV • PT(jet1) > 150 GeV, |h| < 1 • PT(jet2) < 50 GeV • Df(MET,jet1) > 30o limits on MS ~ 660-680 GeV 85pb-1 QCD MC SM bkg: mostly Z->nn+jet(s) updated analysis with 200pb-1 and new JES in process ... n = 6 and MS = 0.7 TeV Eric Kajfasz, CPPM/D0

  16. TeV-1 Extra Dimension:Virtual Exchange of Z/g KK states (> 1 EM w/ track match) same procedure as for LED analysis but with virtual Z/g KK states effects parameterized by:hC = p2/3MC2 Nexp = 12.1 (4.3 QCD), Nobs = 9 => Limit set as done for LED:hC < 2.63 TeV-2 => MC > 1.12 TeV @ 95% CL D0: ee 200pb-1 signal for hC = 5 TeV-2 QCD D-Y+ QCD H1: DIS KK states modify the Z/g propagators: 1/Q2 -> 1/Q2 + hC 1/(Q2+MZ2) -> 1/(Q2+MZ2) + hC Fit to e+p and e-p data => MC > 1.0 TeV @ 95% CL LEP from combined precision EW measurements: MC > 6.6 TeV Eric Kajfasz, CPPM/D0

  17. RS Extra Dimension • Graviton KK states well separated => resonant graviton search: • CDF analyses: • ee and mm: binned likelihood method • gg: counting limits using 3s mass window around resonance • D0 analysis: • diEM: using 3s mass window method Eric Kajfasz, CPPM/D0

  18. RS Extra Dimension ee, mm, gg • mm: • 2 isolated m’s w/ PT>20GeV • |hm1| <1, |hm2|<1.5 • cosmic veto  ee  • gg: • 2 isolated g’s w/ ET>15GeV • CC • ee: • 2 isolated e’s w/ ET>25GeV • CC or CP data agree with expected SM bkg ... Eric Kajfasz, CPPM/D0

  19. RS Extra Dimension ee, mm, gg • cross-section limits computed from binned likelihood (ee,mm) and 3-s mass window (gg) • compare to R-S cross-section for different values of the k/MPL parameter.  ee  => exclusion contour plot ... Eric Kajfasz, CPPM/D0

  20. RS Extra Dimension ee, mm, gg Lower limits on MG (GeV) for k/MPL = 0.1 • Further improvement can be achieved by: • using mass window method for dilepton channels • combining channels Eric Kajfasz, CPPM/D0

  21. RS Extra Dimension diEM same diEM data set as for LED search 200pb-1 CC-CC + CC-EC signal RS Graviton MG = 300 GeV D-Y+ direct gg + QCD QCD 785 GeV data agree with expected SM background => set limits with mass window method Eric Kajfasz, CPPM/D0

  22. Summary MS (K = 1) n Eric Kajfasz, CPPM/D0

  23. Conclusions • Tevatron, CDF&D0 working well • CDF&D0 have by now each ~ 450pb-1 on tape • Tevatron and HERA are great tools to start looking for ED’s • Very competitive results and even most stringent limits are starting to come out • There is still room for improvement, so stay tuned. • However, for the final word on some models, we may very well need to wait for LHC ... Eric Kajfasz, CPPM/D0

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