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Search for Extra-Dimensions at LHC

Search for Extra-Dimensions at LHC. Ilya Korolkov (IFAE/ATLAS). Outline Search for Large Extra-Dimensions (LED). KK Graviton Direct Production -> missing Et KK Graviton Virtual Exchange -> Drell-Yan, … 1/TeV Model. Z/ γ KK excitations -> multi-TeV resonances

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Search for Extra-Dimensions at LHC

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  1. Search for Extra-Dimensions at LHC Ilya Korolkov (IFAE/ATLAS) • Outline • Search for Large Extra-Dimensions (LED). • KK Graviton Direct Production -> missing Et • KK Graviton Virtual Exchange -> Drell-Yan, … • 1/TeV Model. • Z/γ KK excitations -> multi-TeV resonances • Search for Randall-Sundrum Signals (RS). • KK Graviton -> TeV resonances • Radion -> Higgs-’like’ signature • Search for Extra Dimensions and Something. • LED and Unification -> αsrunning • Summary.

  2. LED Signatures at LHC. Virtual Production Direct Production … Gravity propagates in the flat, compactified EDs, boundary conditions in the EDs give rise to the periodic wave function: KK modes in 4D of the Graviton -> Direct or Virtual production of Gravitons KK modes give extra contribution to SM cross-sections, a graviton can be connected to any vertex or propagator of the SM

  3. LED: Search for KK Graviton, Direct Production.(ATLAS studies) L. Vacavant and I. Hinchliffehep-ex/0005033, J. Phys., G : 27 (2001) no.8, pp.1839-50 -1 fb Signature: jet + missing Et Bgds: jZ(->vv), jW(->lv) Cross-section from [hep-ph/9811291] -> implemented in ISAJET ATLFAST signal and bgd simulations Selection: Trigger optimization Isolated lepton veto (eff~98%) Central jet (|eta|<2.5) Large missing Et Data Sample: 100 ( = 1 year HL)

  4. LED. Search for KK Graviton, Direct Production.(ATLAS studies) cont’d. L. Vacavant and I. Hinchliffehep-ex/0005033, J. Phys., G : 27 (2001) no.8, pp.1839-50 -1 fb Studies: Smax > 5 >100 signal evts (50 LL) Et cut > 1 TeV Disentangle Md and δ is difficult -> run LHC at different energy At 10TeV, need 5% accuracy on Cross-section ratio -> at least 50 are needed

  5. LED. Search for KK Graviton Virtual Exchange. (ATLAS studies/ ll+X, γγ+X final states)V. Kabachenko, A. Miagkov, A. ZeninATL-PHYS-2001-012 -1 fb Signature: deviation of DY from the SM Cross-section from [hep-ph/0003306] Full expression for the summed G(k) propagator (numerical calculations) Bgd: SM ATLFAST++ simulations Selection: Pt(ll)>50GeV, |eta|<2.5 m0<Mll<0.9Ms Data Sample: 10, 100 pp-> γγ+X gives similar results ll+X, γγ+X Somewhat better sensitivity than direct production

  6. 1/TeV Model Signatures at LHC. Gravity propagates in LEDs and SM gauge fields and Gravity propagate in the <small> (~1/TeV) ED -> 4d KK excitations of gauge fields -> distortion of EW parameters <- constraints from LEP: Mc>4TeV -> direct production of Z(k), gamma(k)

  7. 1/TeV Model. Search for Z/γ KK excitations. (ATLAS studies/ ee, μμ final states)G. Polesello and G. Azuelos hep-ph/0204031 Mc = 4TeV -1 fb Mee(GeV) Assumptions: one <small> dimension compactified on S1/Z2 orbifold all SM fermions on same fixed point m(k)^2=m0^2+(kMc)^2 m1~4TeV, m2~8TeV (out of reach) Signature: pp -> Z1/γ1 -> ee/μμ Bgds: jZ(vv), jW(l v) Matrix elements from [hep-ph/9909232] -> implemented in PYPHIA ATLFAST simulations Selection: Pt(l)>20GeV, |eta|<2.5 Isolated leptons Mll>1TeV Studies reach from peak region: 100 , sign>5, at least 10 events Mc up to 5.8TeV can be probed optimal reach if no resonance is seen, likelihood analysis can be performed on mass spectrum to infer on the compactification mass Mc up to 9.5TeV can be probed (ee only)

  8. Signatures in Randall-Sundrum Model at LHC. brane <warped> metric of only one ED -> 4D KK excitations Graviton and Higgs-’like’ Radion scalar stabilizes the size of ED Phenomenology narrow resonance coupling to gg enhanced other branching modified may mix with the SM Higgs φ -> hh (unlike SM Higgs) Unknown Parameters mass scale Λ mφ ξ – mixing parameter

  9. RS. Search for KK Graviton excitations. (ATLAS studies / ee final state)B.C. Allanach, K. Odagiri, M.A. Parker, B.R. Webber ATL-PHYS-2000-029 exp. resolution -1 fb Assumptions: k/Mpl = 0.01 => smallest coupling, narrow resonance, m1=1.5TeV Signature: G - >ee(best resolution) Bgds: SM HERWIG generator ATLFAST simulations Selection: Isolated lepton veto Central jet (|eta|<2.5) Data sample 100 Studies maximum reach in the test model: 0.5 TeV < m1 < 2.08TeV Note: study is not limited to the RS model, if: resonances narrower than exp. Resolution resonances are well spaced

  10. RS. Search for KK Graviton excitations. (ATLAS studies) cont’d. B.C. Allanach, K. Odagiri, M.A. Parker, B.R. Webber ATL-PHYS-2000-029 Unique feature of Graviton: spin 2 ( contrary to Z’) -> Likelihood functions for two hypotheses: DY only (spin 1) test model + DY #events is increased until spin-1 hypothesis is ruled out -> test model spin-1 is ruled out at CL90% up to m1=1.72TeV

  11. RS. Search for KK Graviton excitations. (example from the CMS studies) M.C, Lemaire, J.P. Pansart, B.Fabbro, A. Van Lysebetten, G.Wrochna (CMS note in preparation) G->μμ G->ee -1 fb Assumptions: k/Mpl = 0.01 => smallest coupling, narrow resonance m1=1.5TeV Signature: G -> ee, μμ Bgds: SM PYPHIA 6.203 generator CMSJET simulations Data sample 100 Studies maximum reach in the test model at 5σ level m1 < 2.0TeV (ee only) Notes: CMS and ATLAS can explore the whole region of interest. The similarities in the results for two detectors are due to the similarities in the MC specifications.

  12. RS. Search for Radion. (ATLAS studies) G. Azuelos, D. Cavalli, H. Przysiezniak, L. Vacavant hep-ph/0204031 -1 fb Assumptions: Λ = 1TeV, ξ = 0 Signature re-interpretation of SM Higgs results φ->γγ, φ->ZZ -> 4l Bgds: SM PYTHIA+HDECAY+ATLFAST Data sample: 100 Studies:

  13. Search for Radion. (ATLAS) cont’d G. Azuelos, D. Cavalli, H. Przysiezniak, L. Vacavant hep-ph/0204031 -1 fb Assumptions: Λ = 1TeV, ξ = 0, mφ = 300CeV, mh = 125GeV Signature direct decay φ -> hh -> γγbb Bgds: SM PYTHIA+HDECAY+ATLFAST Selection: two isolated photons, |eta|<2.5 two jets, |eta|<2.5 one is b-taged Studies Minimum integrated luminosity ( ) needed Maximum reach @95% in Λ, for ξ = 0

  14. Gauge Coupling Unification (within LED).(the LHC studies) C.Balazs, B.Laforge hep-ph/0110217 Principle: KK excitations of gauge bosons => power low contribution to the running of gauge coupling => acceleration of running => unification can be brought down to ~30TeV. deviations from expected shape of di-jet cross-section Framework: [hep-ph/9803446] n EDs, size~0.1/TeV fermions in 4D, gauge bosons and gluons in the bulk below 1/size~10TeV MSSM+KK excitations Signature di-jet cross-section (σ~αs^2 at LO, no other couplings) 560<Pt(jet)<5000GeV KK excitations contribute less than 1% below 10TeV MSSM MGUT=1016 GeV MSSM + XD as MGUT~30000 GeV For (4+2) D and R=1/10000 GeV-1

  15. Gauge Coupling Unification (within LED).(the LHC studies) cont’d C.Balazs, B.Laforge hep-ph/0110217 significance Miniman observed di-jet mass Reachable 1/R (GeV) for different number of extra dimensions forNsmax> 5 [pessimistic case in bracket]

  16. Summary. Biased selection of ED studies with ATLAS: Large Extra Dimensions: Direct/Virtual KK Graviton elastic scattering, black holes (not covered in this talk) 1/TeV Models: Z/γ KK excitations, αsrunning. Randall-Sundrum: KK Graviton (direct/virtual), Radion Certainly, the first year of LHC will be very exciting.

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