# Black Holes and Extra Dimensions Jonathan Feng UC Irvine Penn State Physics Department Colloquium 30 January 2003.

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Black Holes and Extra Dimensions Jonathan Feng UC Irvine Penn State Physics Department Colloquium 30 January 2003

Penn State ColloquiumFeng 2 The Standard Model CarrierForceGroup  photon E&MU(1) g gluonStrongSU(3) ZWZW WeakSU(2)

30 January 2003Penn State ColloquiumFeng 3 Tevatron Precise Confirmation

30 January 2003Penn State ColloquiumFeng 4 Grand Unification Unification “explains” SM charges Requires c, massive neutrinos

30 January 2003Penn State ColloquiumFeng 5 Coupling Unification Forces are similar in strength Forces become more similar at high energies and short distances Unification almost exact with supersymmetry Dashed – Standard Model Solid – Supersymmetry Martin (1997)

30 January 2003Penn State ColloquiumFeng 6 What’s Missing The dog that didn’t bark – where’s gravity? Many deep problems, but one obvious one: For protons, gravity is 10 -36 times weaker. Equal for m strong ~ 10 18 GeV, where gravity becomes strong, far beyond expt. (~ TeV).

30 January 2003Penn State ColloquiumFeng 7 Kaluza-Klein Unification Kaluza (1921) and Klein (1926) considered D=5, with 1 dimension rolled into a circle: D=5 gravity  D=4 gravity + EM + scalar g AB  g  + g  5 + g 55 Kaluza: “virtually unsurpassed formal unity...which could not amount to the mere alluring play of a capricious accident.”

30 January 2003Penn State ColloquiumFeng 8 Extra Dimensions Suppose photons are confined to D=4, but gravity propagates in n extra dimensions of size L: For r  L, F grav ~ 1/r 2 For r  L, F grav ~ 1/r 2+n Garden Hose

30 January 2003Penn State ColloquiumFeng 9 … gravity EM Strength r 1/m strong Gravity in Extra Dimensions

30 January 2003Penn State ColloquiumFeng 10 Strong Gravity at the Electroweak Scale Suppose m strong is 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

30 January 2003Penn State ColloquiumFeng 11 Tests of Newtonian Gravity Strength of Deviation Relative to Newtonain Gravity Long, Chan, Price; Hoyle et al.

30 January 2003Penn State ColloquiumFeng 12 Kaluza-Klein States Extra dimensions of size L  towers of Kaluza-Klein particles with masses ~1/L Large extra dims  light states KK states may appear at colliders, in astrophysics (supernova cooling), … f f f ’ graviton __

30 January 2003Penn State ColloquiumFeng 13 Black Holes Solutions to Einstein’s equations Schwarzschild radius r s ~ M BH – requires large mass/energy in small volume Light and other particles do not escape; classically, BHs are stable

30 January 2003Penn State ColloquiumFeng 14   Black Hole Evaporation Quantum mechanically, black holes are not black – they emit Hawking radiation Temperature: T H ~ 1/M BH Lifetime:  ~ M BH 3 For M BH ~ M sun, T H ~ 0.01 K. Astrophysical BHs emit only photons, live ~ forever Form by accretion

30 January 2003Penn State ColloquiumFeng 15 BH creation requires E COM > m strong In 4D, m strong ~ 10 18 GeV, far above accessible energies ~ TeV But with extra dimensions, m strong ~ TeV is possible, can create micro black holes in elementary particle collisions! BHs from Particle Collisions

30 January 2003Penn State ColloquiumFeng 16 Black Holes in the Laboratory What is the production rate? How will you know if you’ve created one? S. Harris

30 January 2003Penn State ColloquiumFeng 17 Black Holes at Colliders BH created when two particles of high enough energy pass within r s. Cross section ~  r s 2 Penrose (1974) D’Eath, Payne (1992) Eardley, Giddings (2001)... Large Hadron Collider (2007): E COM = 14 TeV pp  BH + X Find as many as 1 BH produced per second Dimopoulos, Landsberg (2001)

30 January 2003Penn State ColloquiumFeng 18 Event Characteristics For microscopic BHs,  ~ 10 -27 s, decays are essentially instantaneously T H ~ 100 GeV, so not just photons  j:l:  :,G = 75:15:2:8 Multiplicity ~ 10 Spherical events with leptons, many jets De Roeck (2002)

30 January 2003Penn State ColloquiumFeng 19 Black Holes from Cosmic Rays Cosmic rays – the high energy frontier Observed events with 10 19 eV  E COM ~ 100 TeV But meager fluxes! Can we harness this energy? Kampert, Swordy (2001)

30 January 2003Penn State ColloquiumFeng 20 Use Cosmic Neutrinos Cosmic rays create ultra-high energy neutrinos:   BH gives inclined showers starting deep in the atmosphere Rate: as large as a few per minute somewhere on Earth Feng, Shapere (2001)

30 January 2003Penn State ColloquiumFeng 21 Auger Observatory

30 January 2003Penn State ColloquiumFeng 22 Deep Inclined Showers Coutu, Bertou, Billior (1999) Capelle, Cronin, Parente, Zas (1998) Diaz, Shellard, Amaral (2001) Anchordoqui, Feng, Goldberg, Shapere (2001) HiRes Collaboration (1994)

30 January 2003Penn State ColloquiumFeng 23 Cosmic Ray Black Holes Auger can detect ~100 black holes in 3 years m strong (TeV) Feng, Shapere (2001)

30 January 2003Penn State ColloquiumFeng 24 AMANDA/IceCube Neutrino telescopes may also detect BHs: contained jets through-going muons Similar rate: ~10 BH/year Cosmic rays provide first chance to see black holes from extra dimensions

30 January 2003Penn State ColloquiumFeng 25 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 ……

30 January 2003Penn State ColloquiumFeng 26 Conclusions Gravity is either intrinsically weak or is strong but diluted by extra dimensions If gravity is strong at the TeV scale, we will find black holes in cosmic rays and colliders

30 January 2003Penn State ColloquiumFeng 27 Conclusions Gravity is either intrinsically weak or is strong but diluted by extra dimensions If gravity is strong, we will find black holes in cosmic rays and colliders Anchordoqui, Feng, Goldberg, Shapere (2001) m strong (TeV)

30 January 2003Penn State ColloquiumFeng 28 Gravity Is Weak gravity EM Strength r

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