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Extra Dimensions and Black Holes

Extra Dimensions and Black Holes. Andy Parker Cavendish Laboratory Cambridge. Two views of the world…. Supersymmetry …. Extra dimensions…. …different scales. ….hidden perfection. Epicycles. Typical Ptolemaic planetary model Symmetry is assumed: all orbits are based on circles

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Extra Dimensions and Black Holes

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  1. Extra Dimensions and Black Holes Andy Parker Cavendish Laboratory Cambridge

  2. Two views of the world…. • Supersymmetry …. Extra dimensions…. …different scales ….hidden perfection ATLAS UK Liverpool

  3. Epicycles • Typical Ptolemaic planetary model • Symmetry is assumed: all orbits are based on circles • But the Earth is not at the centre of the circle (the eccentric) • The planet moves on an epicycle • The epicycle moves around the equant From Michael J. Crowe, Theories of the World from Antiquity to the Copernican Revolution. ATLAS UK Liverpool

  4. Supersymmetry • Conventional method to fix Higgs mass: • Invoke SUSY • Double the number of states in model • Invoke SUSY breaking • Fermion/boson loops cancel (GIM) • Higgs mass stabilised! • 105 new parameters (MSSM) • +48 more free parameters if RP not conserved => SUSY is a good pension plan for experimentalists! ATLAS UK Liverpool

  5. Extra Dimensions • Hypothesize that there are extra space dimensions • Volume of bulk space >> volume of 3-D space • Hypothesize that gravity operates throughout the bulk • SM fields confined to 3-D • Then unified field will have “diluted” gravity, as seen in 3-D • If we choose n-D gravity scale=weak scale then… • Only one scale -> no hierarchy problem! • Can experimentally access quantum gravity! • But extra dimension is different scale from “normal” ones • -> new scale to explain Extra dimensions are more of a lottery bet than a pension plan! ATLAS UK Liverpool

  6. Kaluza Klein modes • Particles in compact extra dimension: • Wavelength set by periodic boundary condition • States will be evenly spaced in mass • “tower of Kaluza-Klein modes” • Spacing depends on scale of ED • For large ED (order of mm) spacing is very small - use density of states • For small ED, spacing can be very large. M 4-D brane 1/R r Compactified dimension ATLAS UK Liverpool

  7. Why are SM fields confined to 3-D space? • Interactions of SM fields measured to very high precision at scales of 10-18 m • If gauge forces acted in bulk, deviations would have been measured • KK modes would exist for SM particles • For large ED, mass splitting would be small. ATLAS UK Liverpool

  8. Pioneer 10 • Pioneer 10 is leaving the solar system after 30 years in flight. • Orbit shows deccelaration from force of 10-10 g • Radiation pressure? • Solar? • Antenna? • Heat? • Gas leaks • Time dependence? ATLAS UK Liverpool

  9. x y R Signatures for Large Extra Dimensions at Colliders • ADD model (hep-ph/9803315) • Each excited graviton state has normal gravitational couplings • -> negligible effect • LED: very large number of KK states in tower • Sum over states is large. • => Missing energy signature with massless gravitons escaping into the extra dimensions G ATLAS UK Liverpool

  10. y y x x z z Warped 5-d spacetime Higgs vev suppressed by “Warp Factor” Gravity Planck scale brane Our brane 5th space dimension r ATLAS UK Liverpool

  11. Warped Extra dimensions Consider Randall and Sundrum type models as test case Gravity propagates in a 5-D non-factorizable geometry Hierarchy between MPlanck and MWeak generated by “warp factor” Need : no fine tuning Gravitons have KK excitations with scale This gives a spectrum of graviton excitations which can be detected as resonances at colliders. First excitation is at where Analysis is model independent: this model used for illustration ATLAS UK Liverpool

  12. 1000 GeV 500 GeV • Signal and background for increasing graviton mass 1.5 TeV 2.0 TeV ATLAS UK Liverpool

  13. Search limit Production Cross Section 10 events produced for 100fb-1 at mG=2.2 TeV. With detector acceptance and efficiency, search limit is at 2080 GeV, for a signal of 10 events and S/√B>5 10 events ATLAS UK Liverpool

  14. Angular distribution observed in ATLAS • 1.5 TeV resonance mass • Production dominantly from gluon fusion • Statistics for 100fb-1 of integrated luminosity (1 year at high luminosity) • Acceptance removes events at high cos q* ATLAS UK Liverpool

  15. Graviton discovery contours • Confidence limits in plane of Lp vs graviton mass • Coupling = 1/ Lp • Test model has k/MPl=0.01, giving small coupling. • For large k/MPl coupling is large enough for width to be measured. • (Analysis assumes width<<resolution) ATLAS UK Liverpool

  16. Measurement of the graviton coupling to m+m- Ds.B/s.B • Confidence limits in plane of Lp vs graviton mass • Coupling = 1/ Lp • Test model has k/MPl=0.01, giving small coupling. • For large k/MPl coupling is large enough for width to be measured. • (Analysis assumes width<<resolution) ATLAS UK Liverpool

  17. Photon analysis • Photon pair mass resolution as good as electrons • But background uncertain. For standard model (ptmin=150 GeV) • sHERWIG=0.36 pb • Included: • Not included: • for example • FNAL data indicates sHERWIG is 5x too small  use 1.8 pb • Do not trust cosq distribution for background. Graviton mass (GeV) ATLAS UK Liverpool

  18. Measurement of the graviton coupling to gg • Confidence limits in plane of Lp vs graviton mass • Coupling = 1/ Lp • Test model has k/MPl=0.01, giving small coupling. • For large k/MPl coupling is large enough for width to be measured. • (Analysis assumes width<<resolution) ATLAS UK Liverpool

  19. Graviton to jet-jet backgrounds • k/MPl = 0.08 • (64x higher cross-section) ATLAS UK Liverpool

  20. Graviton to jet-jet search reach • Reach is limited because of high background ATLAS UK Liverpool

  21. Graviton to WW • Look for • Select 1e, 0 m, 2 jets, PTmiss from ATLFAST • hjet <2 • Require Mjj compatible with W mass • take highest pT pair in mass window • Solve for pzn using W mass constraint • Plot MWW look for resonance above SM background • SM background from WW, WZ and ttbar ATLAS UK Liverpool

  22. Graviton to WW: signal and background • WW channel is viable for graviton W+jj ttbar ATLAS UK Liverpool

  23. Graviton to WW channel • Reach of W+jets channel ATLAS UK Liverpool

  24. Exploring the extra dimension • Check that the coupling of the resonance is universal: measure rate in as many channels as possible: mm,gg,jj,bb,tt,WW,ZZ • Use information from angular distribution to separate gg and qq couplings • Estimate model parameters k and rc from resonance mass and s.B • For example, in test model with MG=1.5 TeV, get mass to ±1 GeV • and s.B to 14% from ee channel alone (dominated by statistics). • Then measure ATLAS UK Liverpool

  25. Black hole production • Low scale gravity in extra dimensions allows black hole production at colliders. • Decay by Hawking radiation (without eating the planet) • 8 TeV mass black hole decaying to leptons and jets in ATLAS • 8 partons produced with • pT>500 GeV • Work in progress: Richardson, Harris ATLAS UK Liverpool

  26. Black hole production cross-sections at LHC • Classical approximation to cross-section • (Controversial…) • Very large rates for n=2-6 hep-ph/0111230 10000 evs/yr ATLAS UK Liverpool

  27. Black hole decay • Decay occurs by Hawking radiation • Hawking Temperature TH • Black Hole radius rh • Use observed final state energy spectrum to measure TH and hence n? ATLAS UK Liverpool

  28. Particle spectra from black hole decays • Example: • n=6 extra dimensions • MD = 2 TeV • Mh = 7-7.5 TeV • Hawking Temperature TH= 400 GeV • Multiplicity N~ Mh/2 TH ~ 9 • Electron spectrum deviates from Black body • effect of isolation cut? • recoil effect? • Fit gives 388 GeV All jets Isolated e’s Black body Fit ATLAS UK Liverpool

  29. Extracting n from Black Holes Preliminary! • Fit TH against Black Hole mass • No experimental resolution yet (500 GeV bins…) • Effect of heating? • Input n=6 • Fit gives • n=5.7+-0.2 ATLAS UK Liverpool

  30. Black hole production at the Tevatron pb 105 • Rate expected to be large at Tevatron • n=4 extra dimensions • Cross-section drops rapidly at high mass • Assume 10fb-1 • Non-observation implies MD>1.4 TeV • hep-ph/0112186 Events/yr 102 100 s 10-2 10-5 1.0 1.3 1.6 0.7 MD ATLAS UK Liverpool

  31. Conclusions • Extra dimensional theories provide an exciting alternative to the normal picture of physics beyond the standard model • A wide variety of new phenomena are predicted within reach of experiments. • Exciting times ahead for experimentalists! ATLAS UK Liverpool

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