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Black Holes and Extra Dimensions

Black Holes and Extra Dimensions. Jonathan Feng UC Irvine UCSD Particle Seminar 28 January 2003. The Standard Model. Many interesting problems, but one obvious one: where’s gravity? Gravity is weak, becomes strong at M D ~ 10 18 GeV, far beyond experiment

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Black Holes and Extra Dimensions

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  1. Black Holes and Extra Dimensions Jonathan Feng UC Irvine UCSD Particle Seminar 28 January 2003

  2. The Standard Model • Many interesting problems, but one obvious one: where’s gravity? Gravity is weak, becomes strong at MD ~ 1018 GeV, far beyond experiment • Suppose SM confined to D = 4, but gravity propagates in n extra dimensions of size L: For r>>L, Fgravity ~ 1/r2 For r<<L, Fgravity ~ 1/r2+n UCSD

  3. EM … Strength gravity r MD-1 Gravity in Extra Dimensions UCSD

  4. Strong Gravity at the Electroweak Scale • If D > 4, MD< 1018 GeV possible Suppose MDis 1 TeV, the electroweak unification scale • The number of extra dims n then fixes L • n=1 excluded by solar system, but n=2, 3,… are allowed by tests of Newtonian gravity Arkani-Hamed, Dimopoulos, Dvali (1998) UCSD

  5. Strength of Deviation Relative to Newtonain Gravity Long, Chan, Price; Hoyle et al. Tests of Newtonian Gravity UCSD

  6. f ’ f graviton _ _ f f ’ Kaluza-Klein States • Extra dimensions of size L towers of Kaluza-Klein particles with masses ~ L-1 • Large extra dims  light states • KK states may appear at colliders, in astrophysics (supernova cooling, etc.), … UCSD

  7. Black Holes • BH production requires strong gravity, masses or energies above MD • In 4D, MD ~ 1018 GeV, BHs confined to astrophysics, form by accretion • But in extra D with MD ~ 1 TeV, BHs may be produced in elementary particle collisions UCSD

  8. BHs from Particle Collisions • A Schwarzschild BH (Q = J = 0) has radius • In classical GR, expect a BH to form when two partons pass within rs of each other: • Assume this, and that MBH = s1/2. Myers, Perry (1986) Banks, Fischler (1999) ^ UCSD

  9. BH Formation • Classic study for 4D, b = 0 collision: MBH ~ 0.8 s1/2 D’Eath, Payne (1992) • Heuristic argument for b > 0: J > 0  rs  rKerr: • ~ 0.64 sclassical Anchordoqui, Feng, Goldberg, Shapere (2001) • Classic study generalized to b > 0: s > 0.64 sclassical ; MBH > 0.71s1/2 for b = 0, MBH > 0.45s1/2 for b = bmax Eardley, Giddings (2001) • And to D > 4: s > 1.05 sclassical ; MBH > 0.6s1/2 for b = 0, MBH > 0.1s1/2 for b = bmax Yoshino, Nambu (2002) Ida, Oda, Park (2002) UCSD

  10. Semi-classical Validity For low mass black holes, brane, quantum gravity corrections are important. Require: • Small statistical fluctuations in number of degrees of freedom • Little back reaction from radiation Preskill, Schwarz, Shapere, Trivedi (1991) Both require large entropy S ~ rs2+ n. • BH lifetime t >> MBH-1 For n=6, S(5MD) = 27, S(10MD) = 59 t(5MD) = 10MBH -1, t(10MD) = 12MBH –1 Giddings, Thomas (2001) • Brane effects negligible Semi-classical analysis only valid for MBH > MBHmin = few MD . UCSD

  11. Black Holes at Colliders What is the production rate? • LHC: ECOM = 14 TeV pp BH + X • Find as many as 1 BH produced per second • Note, however, extreme sensitivity to MBHmin. Dimopoulos, Landsberg (2001) Rizzo (2001) UCSD

  12. Event Characteristics • For microscopic BHs, t ~ 10-27 s, decays are essentially instantaneous • TH ~ 100 GeV, so multiplicity ~ 10 • j : l : g : n,G = 75 : 15 : 2 : 8 Emparan, Horowitz, Myers (2000) • Signal: spherical events with hard leptons, photons De Roeck (2002) UCSD

  13. Black Holes from Cosmic Rays • Cosmic rays – the high energy frontier • Observed events with 1019 eV  ECOM ~ 100 TeV • But meager fluxes! Can we harness this energy? Kampert, Swordy (2001) UCSD

  14. Cosmic Neutrinos • Many possible UHE particles – use neutrinos: • s(nN BH) dominates SM processes, since all partons contribute • s(pN BH) << spp. Protons are hopeless Feng, Shapere (2001) UCSD

  15. The Signal • Vertical atm. depth: 10 mwe Horizontal atm. depth: 360 mwe • n BH: uniform at all depths pN X: at top of atmosphere • Signal: deep inclined showers; atmosphere filters out proton, nucleus background Feng, Shapere (2001) UCSD

  16. Deep Inclined Showers Coutu, Bertou, Billior (1999) UCSD

  17. Rates UCSD

  18. Fluxes • Guaranteed: p photoproduction • Choose most conservative: Protheroe, Johnson Stecker (1979) Hill, Schramm (1985) Protheroe, Johnson (1996) UCSD

  19. Other Sources • Additional n sources may exist (for example, to solve the GZK problem) • Below consider only p photoproduction; other sources may increase rates by 2 orders of magnitude UCSD

  20. Apertures • Showers may be detected by ground arrays and air fluorescence Current: AGASA (ground), HiRes (air fluor.) Future: Auger (both) http://www.auger.org UCSD

  21. Auger Observatory UCSD

  22. Apertures Capelle, Cronin, Parente, Zas (1998) Diaz, Shellard, Amaral (2001) Anchordoqui, Feng, Goldberg, Shapere (2001) HiRes Collaboration (1994) UCSD

  23. Current Bounds: AGASA, HiRes • Lower bounds on MD from absence of BHs at AGASA and HiRes for MBHmin = MD . • For n > 3, MD > 1.5 – 2.0 TeV, most stringent bounds to date Anchordoqui, Feng, Goldberg, Shapere (2001) UCSD

  24. MBHmin Dependence Lower bounds on MD for n=1,...,7 from below For MBHmin ~ 10 MD , well into classical regime, bounds are comparable to or exceed all other bounds xmin = MBHmin/MD UCSD

  25. Future Prospects: Auger • Auger begins 2004 — can detect ~100 black holes in 3 years • Provides first chance to see black holes from extra dimensions mD(TeV) Number of BHs at Auger for n = 7, MBHmin = MD UCSD

  26. Comparison with LHC • LHC predictions extremely sensitive to MBHmin • No Auger BHs, MBHmin>5 MD no LHC BHs • Of course, we could see events! ... UCSD

  27. Black Hole Identification • How will you know if you’ve created one? UCSD

  28. S. Harris UCSD

  29. BHs vs. SM • BH rates may be 1000 times SM rate. But • large BH s large rate • large flux  large rate • However, consider Earth-skimming neutrinos: • large flux  large rate • large BH s  small rate Bertou et al. (2001) Feng, Fisher, Wilczek, Yu (2001) UCSD

  30. Quasi-horizontal (dashed) and Earth-skimming showers (dotted) in 5 years. SM explanation (sBH=0) excluded at high CL. UCSD

  31. What You Could Do With A Black Hole If You Made One • Discover extra dimensions • Test Hawking evaporation, BH properties • Explore last stages of BH evaporation, quantum gravity, information loss problem • …… UCSD

  32. Additional Possibilities • Under-ice: AMANDA/IceCube • Radio: RICE, ANITA • Space-based: EUSO/OWL • These may provide BH branching ratios, angular distributions, etc. Anchordoqui, Goldberg (2001) Emparan, Masip, Rattazzi (2001) Uehara (2001) Ringwald, Tu (2001) Ahn, Cavaglia, Olinto (2002) Kowalski, Ringwald, Tu (2002) Jain, Kar, Panda, Ralston (2002) Alvarez-Muniz, Feng, Halzen, Han, Hooper (2002) Anchordoqui, Feng, Goldberg (2002) Iyer Dutta, Reno, Sarcevic (2002) Anchordoqui, Goldberg, Shapere (2002) McKay, etal. (2002) ... UCSD

  33. Conclusions • Gravity is either intrinsically weak or is strong but diluted by extra dimensions • If gravity is strong at ~ 1 TeV, we will find black holes in cosmic rays and colliders MD(TeV) Anchordoqui, Feng, Goldberg, Shapere (2001) UCSD

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