1 / 20

Search for Extra-Dimensions at the LHC

Search for Extra-Dimensions at the LHC. Bertrand Laforge LPNHE Paris CNRS/IN2P3 – Universités Paris 6&7 On behalf of the ATLAS and CMS collaborations. Theoretical Framework Search for Large Extra-Dimensions Search for Randall-Sundrum signals Search for Extra-Dimensions and Unification

britany
Download Presentation

Search for Extra-Dimensions at the LHC

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-Dimensions at the LHC Bertrand Laforge LPNHE Paris CNRS/IN2P3 – Universités Paris 6&7 On behalf of the ATLAS and CMS collaborations • Theoretical Framework • Search for Large Extra-Dimensions • Search for Randall-Sundrum signals • Search for Extra-Dimensions and Unification • Supersymmetry and XD • Conclusion Moriond QCD 2002, Les arcs

  2. Motivations Interests of introducing extra dimensions : • Hierarchy question compactified space-time structure new theorical frameworks (strings, branes, M-theory) • Why Gravitational Interaction is so weak ? Natural with XD ! • XD make possible the unification of interactions at few TeV • Give a lot of work to all physicists (theory&experiment) new ideas, new tools Models and effects Investigated in ATLAS and CMS • Large Extra dimension Model (Flat geometry) • Tev-1 Extra dimension Model • Randall Sundrum (Warped Metric) • Test of coupling unification at low energy

  3. SM 4-brane Large Extra Dimension Antoniadis, Benakli and Quiros Phys.Lett.B331:313-320 (1994) Arkani-Hamed, Dimopoulos and Dvali Phys. Lett B429, 263(1998) Et al. • Gravity becomes strong at a TeV scale : graviton in all D • d Extra Dimensions compactified on a d-torus (same Rc for the d XD) – This is a FLAT geometry - • Boundary conditions in the extra dimensions give rise to periodic wave functions : KK modes in 4D of the graviton • Mn = M0 + n/RC • M2Plank = MDd+2 x RCd Plank Mass is an effective Scale • If MD = 1 TeV then R ~1 mm (for d=2) • KK modes give extra-contribution to SM cross-sections, a graviton can be connected to any vertex or propagator of the SM : bulk Holds only for Flat geometry not for Warped one Curled XD effect through Virtual exchange or Direct production of graviton KK modes

  4. SM y=0 4-brane y = prc Plank Brane : Gravity is strong Randall-Sundrum Model(1 extra dimension…) Randal, Sundrum, PRL 83, 3370 (1999) • Metric depends on where one stands on the XD coordinate y (warped geometry) : Distances shrinks with y : Lp = Mplank exp(-kprc) ~ TeV(no hierarchy) Mplank/Mew  krc~11-12 Graviton resonances in 4D : Mn = xn k exp(-kprc) with J1(xn)=0 [Bessel] = xn (k/Mplank) Lp

  5. Large Extra DimensionSearch for Single Jet + Ptmiss(Direct Graviton production) Isajet + ATLFAST Signal : direct Graviton + 1 jet production Main background : jet + Z(W) [Z nn,Wln] L.Vacavant, I. Hinchliffe (J. Phys. G: Nucl. Part. Phys. 27 (2001) 1839-1850)

  6. 3 years low lumi : 30 fb-1 1 year high lumi : 100 fb-1 Large Extra DimensionSearch for Single Jet + Ptmiss(2) Results S>50 events, Signif.max>5 MDmax= 7.7, 6.2, 5.2 for d=2,3,4 S>100 events, Signif.max>5 MDmax= 9.1, 7.0, 6.0 for d=2,3,4 (100 fb-1)

  7. Large Extra DimensionATLAS Sensitivity to di-photon and di-lepton processes Kabachenko, Miagkov, Zenin (ATL-PHYS-2001-012) pp  l+l- +X Mmin 5 s Selection : Pt>50 GeV |h|<2.5 pp  gg +X 5 s 100 fb-1 Results for the 2 Combined channels d 10 fb-1

  8. Large Extra DimensionTeV-1 Extra Dimension G. Azuelos, G. Polesello (Les Houches 2001 Workshop Proceedings) Fermions are open strings excitations with ends stuck to our brane but gauge Bosons could also propagate in the bulk. If no resonance is seen, likehood analysis can be performed on mass spectrum to infer the compactification mass Search for KK excitations of Z, g, … MC Experiments # Exp. M = 6.045 TeV DM = 205 GeV 100fb-1 100fb-1

  9. Search for Graviton Resonances in ATLAS (1) B.C. Allanach, K. Odagiri, M.A. Parker, B.R. Weber (JHEP 09 (2000) 019 – ATL-PHYS-2000-029) Generic Search for any Model with Narrow Gravitons gg (qq)  G  e+e- Signal can be seen for M in the range [0.5, 2.08]TeV for worse Randal Sundrum Scenario (k/Lp=0.01) M=1.5 TeV 100fb-1 Experimental resolution

  10. Angular distributions Search for Graviton Resonances in ATLAS (2) B.C. Allanach, K. Odagiri, M.A. Parker, B.R. Weber (JHEP 09 (2000) 019 – ATL-PHYS-2000-029) Signature : graviton has spin 2 gg (qq)  G  e+e- M=1.5 TeV 100fb-1 Calculations made using HELAS customed for spin-2 ATLAS can distinguish spin 2 vs 1 up to 1.72 TeV

  11. CMS Graviton SearchRS scenario (1) M.C. Lemaire, J.P. Pansart, B. Fabbro ,A. Van Lysebetten, G. Wrochna (CMS note in preparation) s evolution with coupling Virtual exchange of Graviton : - Decay to e+e- preliminary Generation of Randall Sundrum graviton with Pythia 6.203 decaying in electron positron pair and detector simulation with CMSJET

  12. CMS Graviton SearchRS scenario (2) k/Mpl = 0.01 Worse case K factor= 1.38 from comparison of Pythia Drell-Yan cross-sections with CDF data 1 TeV 2 TeV C = 0.01 C = 0.01 e+e- Channel • With 100 fb-1 CMS experiment should be able to see the Randall Sundrum graviton at the 5s level for masses up to 2000 GeV for the weakest coupling (c=k/Mpl = 0.01). • For c=0.2, 4 TeV can be reached Mee Mee C = 0.01 1 TeV m+m- Channel also investigated

  13. CMS Graviton SearchRS scenario (3) CMS Note 2002/03 (to be released very soon) Ideal Detector Phenomenological Bounds CMS can explore the whole ROI 3 TeV CMS Detector  acceptance and resolution effects can be important

  14. Search of Radion in R.S. G.Azuelos,D.Cavalli,L.Vacavant,H.Przysiezniak (Les Houches Workshop 2001 Proc.) Graviscalar Radion Graviton Field New Mecanism to stabilize XD radius rc !!! Goldberger & Wise Phys. Rew. Lett. 83, 4922 (1999) ADDITIONAL BULK SCALAR !  acquires a mass  likely to be lighter than the J=2 KK excitations  radial excitations of compactified dim.

  15. Radion search ATLAS Analysis RS Radion Main Features : -  and SM Higgs mix: -   hh, unlike SM Higgs - partial widths scale like -2 for =0 - narrow resonance - gg coupling enhanced SM Higgs + Radion (no mixing) • Parameters Of The Model • m :mass :scale • :-H mixing mh=125 GeV/c2 =1TeV SM Higgs Want to know more? Giudice,Rattazzi,Wells, hep-ph/002178 Goldberger,Wise,PLB 475(2000)275

  16. Simulation Results ( Using a modified version of Hdecay) 100fb-1, = 0,  = 1(10) TeV   S/B~10(.1) for 80<m<160GeV/c2   ZZ(*)S/B~100(1) for 200<m<600GeV/c2 ->hh->bb max=4.6TeV for m= 300 GeV/c2 and max=5.7TeV for m= 600 GeV/c2 ->hh->bb Requiring a minimum of 10 evts and S/B5: max=1.05TeV for m= 300 GeV/c2 and max=1.4TeV for m= 600 GeV/c2 Uncertainties in background considerably affect observability of this channel when m= 300 GeV/c2

  17. -1 -1 -1 as ai ai Test of Unification at low Scale (1) C.Balazs, B. Laforge [Phys. Lett. B 525 (2002) 219-224] Introduction of extra dimensions to solve the hierachy problem • unification of couplings at MGUT << 1016 GeV • Gauge Bosons can propagate in the Bulk • Modification of RGE (E. Dudas, R. Dienes, T. Ghergetta, hep/ph 9803466 and hep/ph9807522) How can we be experimentally sensitive to unification ? • Look at violation of the expected ([MS]SM) RGE through high statistics [MS]SM channels MSSM MGUT=1016 GeV MSSM + XD MGUT~30000 GeV For (4+2) D and R=1/10000 GeV-1

  18. Data analysis at LHC Results for ATLAS 100 fb-1 This is NOT a resonance This is NOT a resonance

  19. ( ) SUSY & XD K. Assamagan, A. Deandrea [Atlas Phys. Note in preparation] H+/-t+/-nL,R • Model with a Higgs Doublet • Singlet neutrino can go in XD • polarisation measurable using • pn decay, (pp/Et-jet dist.) Sensitive variable :H+/- transverse mass and t polarisation(one of the 2 polarisations is strongly suppressed in MSSM and enhanced if n in the bulk with XD)

  20. Conclusion • XD : a chance to understand the Hierachy problem as a space-time structure • XD : a chance to observe signs of coupling unifications at low scale (few TeV) • XD : a lot new ideas and contacts between Theorists & experimentalists • ATLAS and CMS analyses cover a large part of the different ideas proposed to investigate if XD really exist. These searches need : • A good Et measurement • A good Energy and angular reconstruction for high Pt leptons and jets • A good Identification of photons (capability to reject p0) • A good b-tagging Expected Detector performance should enable to observe XD at a few TeV Scale We are ready to face the next ideas to be tested What’s Next : black holes ?

More Related