1 / 23

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

louisa
Télécharger la présentation

Search for Extra-Dimensions at pp and ep Colliders

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  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

More Related