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ED@LHC

Extra Dimensions @ the LHC. ED@LHC. M ü ge Karag ö z Ü nel CERN 24 th Jan 2008. Based on a talk given in 2007, so most ATLAS and TeV results not updated. Sorry!. History Illustrated. 1915. 1925. 1687. ED@LHC. ~1960. Extra Dimensions. Not a new idea!

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ED@LHC

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  1. Extra Dimensions @ the LHC ED@LHC Müge Karagöz Ünel CERN 24th Jan 2008 Based on a talk given in 2007, so most ATLAS and TeV results not updated. Sorry!

  2. History Illustrated 1915 1925 1687 ED@LHC ~1960

  3. Extra Dimensions • Not a new idea! • Kaluza and Klein tried to unify electromagnetism and General Relativity in the ‘20s by adding a 4th spatial dimension • In late ‘90s, models attempt to solve the hierarchy problem (MPl >> MEW) • A lot of variations since then… • Searches at current colliders boomed.. ED@LHC

  4. Obtain size of the ED (compactification radius) from the gravitational potential (Gauss’ law) MPl ~ 1019 GeV, MPl(4+n)~MEW “Modifying” Gravitational Law • n=1 R~1013 cm: deviations of Newtonian gravity over solar distances; excluded. • n=2 (R~ 100m - 1mm): within reach, ruled out by Eot-Wash table-top (<150m) • n>2, gravity modified at distances we can probe at colliders. ED@LHC • Assume MPl(4+n) ~ mEW,

  5. Large Extra Dimensions (LED, ADD): n > 0 (n > 2), compactified, flat Graviton in bulk Could be as large as 0.1mm TeV-1 ED (DDG): n ≥ 1 (n = 1) Gauge bosons in bulk as well Warped Extra Dimensions (RS): n = 1, highly curved 2-branes solution: RS1 k/MPl, k: curvature, warp factor Universal Extra Dimensions (UED): n = 1, flat, MUED: only1 ED KK-number conservation All SM particles in the bulk Lots of KK spectra Searches Concentrated on Arkani-Hamed, Dimopoulos, Dvali Phys Lett B429 (98) Dienes, Dudas, Gherghetta Nucl Phys B537 (99) ED@LHC Randall, Sundrum Phys Rev Lett 83 (99) Appelquist, Cheng, Dobrescu Phys. Rev. D 64 (01)

  6. Bosonic KK modes: simpler signatures Virtual or resonance exchange ll  ZZ qq Large ED (ADD): • Graviton in bulk • DY interference, or missing ET ED@LHC TeV-1 ED (DDG): • Gauge Bosons and Higgs in bulk • spin-1 KK resonances • DY interference Warped ED (RS): • Graviton resonances jet+MET +MET emission Universal ED (UED): • spin-1 KK resonances

  7. Effective s for continuum G SMint sHewett Large Extra Dimensions (ADD) • Flat large EDs generate tower of KK gravitons with mass splitting ~ 1/RC continuum of graviton states • SM fields localized within 3D-brane • Size of ED determined by the fundamental scale MD and # ED Signatures: • Virtual production with DY interference  excess above continuum • Real graviton emission with jet or photon ED@LHC n<=2 ruled out (by Eot-Wash) MD < 1TeV ruled out by Tevatron

  8. Randall Sundrum (Type I) Brane metric scales as function of bulk position Coupling constant: c= k/MPl, k: curvature scale Well separated narrow-width graviton mass spectrum with masses mn=kxnekrcπ (J1(xn)=0) c>0.1 forbidden TeV Planck Bulk (y) Warped Extra Dimensions ED@LHC

  9. From Tevatron to LHC Most stringent limits to date from colliders: • CDF : k/MPl= 0.1, mG > 889 GeV (comb gg +ee) • D0 : k/MPl = 0.1, mG > 865 GeV (diEM) ED@LHC • But we huge BSM reach increase from 2TeV to 14 TeV!

  10. Di-photon/dilepton invariant mass Manageable backgrounds Min invariant mass cut extends reach Signal SM Belotelov et al., CMS PTDR 2006 Virtual Exchange Searches (LED) ED@LHC Kabachenko et al. ATL-PHYS-2001-012 • 2 OS muons & Mμμ>1 TeV • Bkgrd: mainly Irreducible DY • PYTHIA + CTEQ6L, Kf=1.38 CMS 5s Sensitivity for n=6..3 • 1 fb-1: ~4.0-5.5 ТеV • 100 fb-1: ~5.5-8.2 ТеV ATLAS Sensitivity for n=5..2 100fb-1: MD ~6.3-7.9 TeV

  11. L.Vacavant, I.Hinchcliffe J. Phys G 27 (01) LED from Graviton Emission pp→jet+G Signature: high ET jet + MET (from escaping G) Bkgrnd: irreducible jet+Z/W via invisible decays ED@LHC ATLAS sensitivity in 100 fb-1 CMS sensitivity pp→g + G MD= 1– 1.5 TeV, n<7, 1 fb-1 2 - 2.5 TeV, n<7, 10 fb-1 3 - 3.5 TeV, n<6,100 fb-1 much lower rates than mono-jet signature Signature: high-pT photon + MET Bkgrnd: irreducible Zγ → , and reducible fakes CMS NOTE 2006/129 Rates for MD≥ 3.5TeV are too low for 5σ discovery with systematics

  12. Allanach et al, hep-ph 0006114 M=1.5, 1.75, 2 TeV No Kf for signal SM WED RS1 Searches ATLAS Spin exploitation • Use cosq* distribution of the dilepton system • Determine Spin-2 nature of graviton at 90% C.L. up to MG = 1720 GeV with 100 fb-1 CMS PTDR results • Use ll and gg: B(G->gg) = 2* B(G->ee/mm) • Reach in ee and gg similar (unmanageable gg bkgrnd) (also not enough stats) • CMS can detect at 5s up to 1.8 TeV (c=0.01) and 3.8 TeV (c=0.1) with 100 fb-1 • Uncertainties’ effect in mass ~150 GeV ED@LHC

  13. ppZ(1 ) /g(1)e+e- Azuelos, Polesello EPJ D C39 Sup.2 (04) Clerbaux et al, 06 TeV-1 Searches in Dileptons • 1 ED with small enough compactification for gauge bosons to travel in bulk • All fermions localized at a fixed point (M1) • destructive interference with SM GB • cKK = √2 cSM • q and l at opposite points (M2) • constructive interference • V(k) appear as resonances: Mk = √(M02+k2/R2), k=1,2,… • search for anomaly/bump in dilepton invariant mass ED@LHC • ATLAS5s reach in Mll (fast simulation): MC = 5.8 TeV in 100 fb-1 • If no peak, limit ~13 TeV in 300 fb-1 • CMS5s reach in Mee (full simulation): MC = 6.0 TeV in 80 fb-1 Z(1) can be discriminated from Z’ for up to ~5 TeV with 300fb-1

  14. J Aguilar Is it a Z’ or RS Graviton? ED@LHC Handles: • Mass little info about models (unless blessed enough to observe series of KK bumps) • Cross section info about couplings • BR test couplings & universality (G has well-defined ratio between ll/gg/ZZ and Z’ has no gg coupling ) • Angular distribution/asymmetries spin and couplings (even then various Z’ are not easy to tell)

  15. 4 TeV 6 TeV ATLAS W(1) Searches TeV-1 searches in lepton+MET • Feasibility using fast simulation for • Search for a peak in MT(ln) • Analysis challenges: • MET measurement, • for muons, the edge washed out. • In 100 fb-1 • detect a peak, if MC(= R-1)<6 TeV • fermionic couplings measured, if MC <~ 5 TeV • If none observed, • use -ve interference with SM W (en only) • a limit of MC < 11.7 TeV Polesello, Patra EPJ Direct C 32 Sup.2 (04) ED@LHC

  16. Formation MBH = √S Parton Rs Parton Webber et al, 2005 Those m-Blackholes Arise from models with ED Could be produced when ECM > MPl Need QT of gravity as MBH approaches MPl σ ~ πRS2 ~ 1 TeV-2 ~ 10-38 m2 ~ O(100)pb LHC  Black Hole Factory, rates as high as 1Hz! ED@LHC Nick Brett If the impact parameter of a 2-parton collision < Schwarzschild radius Rs, then a black hole with MBH is formed. BH from LED, possible from RS as well

  17. Distinguishing features High Multiplicity, ΣET, Sphericity, MPT Democratic Decay Theory estimates limit systematics Charybdis event generator Decay Harris, et al. JHEP05 (2005) 053 6.1 TeV MBH J. Tanaka , “Search for Black Holes”, 24/05/03 Athens m-Blackhole Detection at ATLAS BH lifetime ~ 10-27 – 10-25 seconds! Decays with equal probability to all particles via Hawking Radiation (roughly a blackbody spectrum) evaporates into (hadron : lepton)= (5 : 1) accounting for t, W, Z and H decays ED@LHC Giddings,Thomas PRD65(2002)056010 N=6 gives a larger yield than n=2 “I have never won the national lottery, so go for it!” – anony, on BH threat from LHC!

  18. SM particles propagate in bulk with 1 ED KK-parity conservation Leads to stable LKP as DM candidate Pair of KK modes, no virtual KK modes  Limits are weaker due to small cross sections 600 570 g1 1 Q1 Z1 L1 Minimal Universal ED ED@LHC CMS g1g1/G1Q1/Q1Q1 analysis: • 4 low-pT isolated leptons (2 pairs of OS same flavour) l + m jets (m=4,3,2) + MET (from 2 undetectedg1) • Irreducible background: tt + m jets, 4 b-jets, ZZ, Zbb • Discovery reach: MC ~600 GeV for 1 fb-1 LEP + TeVatron limits: MC > 300-400 GeV

  19. Beauchemin, Azuelos ATL-PHYS-PUB-2005-003 Signal BG MKK=1.3TeV 200 600 1000 1400 MET (GeV) Thick brane Universal ED • Thick brane solutions: One UED embedded in (SUSY) LED • Gravity-matter interactions break PKK • Pair of KK partons decaying to SM parton+graviton: g1/g1->q/g+G • Measure excess of dijets with large MET • Main backgrounds: dijets + Z/W decaying invisibly ED@LHC Sensitivity: • if MC = 1.3 TeV, clear probing with 6 pb-1 • 5σ up to 2.7 TeV with 100 fb-1

  20. q Q q Z 1 1 ( ) ~ ± l near c 0 m l 2 ( ) 1 ~ m l far g m l 1 ~ c 0 1 Is it SUSY or UED? SUSY ~ ED@LHC UED Matchev UED decays are similar to SUSY: how to separate? • Look for 2nd level KK modes (SUSY has none) - might be too heavy to observe • UED KK states are same spin of SM particles (SUSY are not) - use dilepton invariant mass - use asymmetry in lq mass • use q or qbar, near and far lepton invariant mass • Success of method SUSY point dependent • Expected to work at 100-150 fb-1

  21. RS with Custodial Symmetry • Favourite model building in warped space • Gauge hierarchy problem, unification • Fermion masses (localizations in the bulk) • Dark Matter candidate, “LZP”, CHAMP-like signatures • Ingredients of model building: • embed into SU(2)LxSU(2)RxU(1) (hep-ph/0612048) • Additional custodial symmetry in SU(2)LxSU(2)R to protect EW observables (Z→bb) • Light degenerate KK fermions (“custodians”) with no zero modes bR,L,Q = 2/3, -1/3, 5/3 ED@LHC • Strategy: • KK quarks searches and related signatures through multi-W events of bR decays • Uncommon in SUSY searches • Stay as inclusive as possible • Multi-W events are generally interesting (WW scattering etc..)

  22. Signature: 4W + 2b-jets Production & Decay ED@LHC • Strong interaction pair production dominates • Simulate tW decay modes of bR, Scale up for total rate • In 10fb-1 of data 22k tW from q5/3 at 500 GeV • Count Ws in hadronic decays • Overwhelming background: ttbar

  23. ED spectra is much wider now wrt a few years ago. If ED exists at the TeV scale, we will be able to observe inclusive signatures. CMS and ATLAS reaches for KK resonances are similar. With < 60 fb-1 LHC is expected to completely cover the RS1 region of interest. Many exclusive studies will be carried out with few fb-1 data… Blackholes may be the “smoking gun” from early data as well as resonances. Conclusions ED@LHC

  24. Flatland: A Romance of Many DimensionsWith Illustrationsby the Author, A SQUARE[Edwin Abbott Abbott] Dedication ToThe Inhabitants of SPACE IN GENERALAnd H.C. IN PARTICULARThis Work is DedicatedBy a Humble Native of FlatlandIn the Hope thatEven as he was Initiated into the MysteriesOf THREE DimensionsHaving been previously conversantWith ONLY TWOSo the Citizens of that Celestial RegionMay aspire yet higher and higherTo the Secrets of FOUR FIVE OR EVEN SIX DimensionsThereby contributingTo the Enlargement of THE IMAGINATIONAnd the possible DevelopmentOf that most and excellent Gift of MODESTYAmong the Superior RacesOf SOLID HUMANITY ED@LHC

  25. BACKUP ED@LHC

  26. RS Graviton resonance search • B(G→ZZ) = 0.05 (x2 B(G→ee)) • 4 very isolated electrons in ZZ • consistent with null observation at MG > 500 GeV • not yet sensitive for limits, need more luminosity Tevatron: Other Signatures LED Graviton emission search • Monojet + MET • Backgrounds: Z→nn+jets, W→ln+jets, QCD dijet. • Expected 819±71, Observed 779. • LEP still better at low MD and n ED@LHC

  27. M mew b Pl PP Motivations Ilustrated ED@LHC

  28. 22 m 46 m the Detectors ED@LHC Tracker:s/pT 1.5 10-4 pT 0.005 EM Cal:/E  3%/E(GeV)  0.5% Hadron Cal:/E  100% / E(GeV)  5% Mu Spec: s/pT 5% at 1 TeV/c (from Tracker) • Inner Tracking(||<2.5, 2T solenoid) : • Silicon pixels and strips • Transition Radiation (e/ separation) • Calorimetry (||<5) : • EM : Pb-LAr, Accordion shape • HAD: Fe/scintillator (centr), Cu/W-LAr (fwd) • Muon Spectrometer (||<2.7, 4T toroid) : • air-core toroids with muon chambers • Tracking (||<2.5, 4T solenoid) : • Silicon pixels and strips • Calorimetry (||<5) : • EM : PbWO4 crystals • HAD: brass/scintillator (centr+ end-cap), Fe/Quartz (fwd) • Muon Spectrometer (||<2.5) : • return yoke of solenoid with mu chambers

  29. C = 0.01 (coupling constant) (1-5 fb-1) First data C =0.1 Long term S Ferrag Mc= 6 TeV 2,4,6 ED Dimuon Mass How well do we know? The apparatus: • Detector effects need to be understood • 5 discovery reach for RS gravitons in mm needs ~50% less data if alignment is optimal! ED@LHC The theory: • For LED, PDF uncertainties claimed to cancel reach above MC=4TeV • NLO corrections ~1.6

  30. First Physics Run in 2008 How many events per experiment at the beginning ? l  e or  Assumed selection efficiency: W l, Z ll : 20% tt  l+X : 1.5% (no b-tag, inside mass bin) ~ 105 J/Psi  + Y ll similar statistics to CDF, D0 today ED@LHC + lots of min-bias and jets (107 events in 2 weeks of data taking if 20% of trigger bandwidth allocated) 1 fb-1  6 month at 1032, =50% 5 fb-1  3 month at 1032 and 3 month at 1033, =50% 10 pb-1 1 month at 1030 and < 2 weeks at 1031,=50% 100 pb-1 few days at 1032 , =50% F. Gianotti, Ichep06 • Large statistics of EW sample in a few weeks!

  31. Gokhan Unel, Athens07 RS ED & Z(n) ED@LHC

  32. Experimental Bounds on MD [TeV] at 95% CL ED@LHC Karina F. Loureiro, C2CR07

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