Black Holes and Extra Dimensions

Jonathan Feng

UC Irvine

UCSD Particle Seminar

28 January 2003

January 2003 UCSD Feng 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

January 2003 UCSD Feng 3

…

gravity

EM

Str

engt

h

rMD-1

Gravity in Extra Dimensions

January 2003 UCSD Feng 4

Strong Gravity at the Electroweak Scale

• If D > 4, MD < 1018 GeV possible

Suppose MD 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

Arkani-Hamed, Dimopoulos, Dvali (1998)

January 2003 UCSD Feng 5

Tests of Newtonian GravitySt

reng

th o

f D

evia

tion

R

elat

ive

to N

ewto

nain

Gra

vity

Long, C

han, Price; H

oyle et al.

January 2003 UCSD Feng 6

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.), …

f

f f ’

f ’graviton

_ _

January 2003 UCSD Feng 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

January 2003 UCSD Feng 8

• 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.

BHs from Particle Collisions

Banks, Fischler (1999)

Myers, Perry (1986)

^

January 2003 UCSD Feng 9

• 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 classical

Anchordoqui, Feng, Goldberg, Shapere (2001)

• Classic study generalized to b > 0:

> 0.64 classical ; MBH > 0.71s1/2 for b = 0, MBH > 0.45s1/2 for b = bmax

Eardley, Giddings (2001)

• And to D > 4:

> 1.05 classical ; MBH > 0.6s1/2 for b = 0, MBH > 0.1s1/2 for b = bmax

Yoshino, Nambu (2002)Ida, Oda, Park (2002)

BH Formation

January 2003 UCSD Feng 10

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 radiationPreskill, Schwarz, Shapere, Trivedi (1991)

Both require large entropy S ~ rs2+ n .

• BH lifetime >> MBH-1

For n=6, S(5MD) = 27, S(10MD) = 59

(5MD) = 10MBH -1, (10MD) = 12MBH

–1

Giddings, Thomas (2001)

• Brane effects negligible

Semi-classical analysis only valid for MBH > MBHmin = few MD .

Semi-classical Validity

January 2003 UCSD Feng 11

Black Holes at CollidersWhat 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 MBH

min. Dimopoulos, Landsberg (2001)Rizzo (2001)

January 2003 UCSD Feng 12

Event Characteristics• For microscopic BHs,

~ 10-27 s, decays are essentially instantaneous

• TH ~ 100 GeV, so multiplicity ~ 10

• j : l : : ,G = 75 : 15 : 2 : 8

Emparan, Horowitz, Myers (2000)

• Signal: spherical events with hard leptons, photons De Roeck (2002)

January 2003 UCSD Feng 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)

January 2003 UCSD Feng 14

Cosmic Neutrinos

Feng, Shapere (2001)

Many possible UHE particles – use neutrinos:

Ndominates SM processes, since all partons contribute

pN<< pp. Protons are hopeless

January 2003 UCSD Feng 15

The Signal

• Vertical atm. depth: 10 mwe

Horizontal atm. depth: 360 mwe

• BH: uniform at all depths

pN X: at top of atmosphere

• Signal: deep inclined showers; atmosphere filters out proton, nucleus background

Feng, Shapere (2001)

January 2003 UCSD Feng 16

Deep Inclined Showers

Coutu, Bertou, Billior (1999)

January 2003 UCSD Feng 17

Rates

January 2003 UCSD Feng 18

• Guaranteed: photoproduction

• Choose most conservative: Protheroe, Johnson

Fluxes

Stecker (1979)Hill, Schramm (1985)

Protheroe, Johnson (1996)

January 2003 UCSD Feng 19

• Additional sources may exist (for example, to solve the GZK problem)

• Below consider only photoproduction; other sources may increase rates by 2 orders of magnitude

Other Sources

January 2003 UCSD Feng 20

• Showers may be detected by ground arrays and air fluorescence

Current: AGASA (ground),HiRes (air fluor.)

Future: Auger (both)

Apertureshtt p://w

ww

.auger. org

January 2003 UCSD Feng 21

Auger Observatory

January 2003 UCSD Feng 22

Apertures

Capelle, Cronin, Parente, Zas (1998)Diaz, Shellard, Amaral (2001)

Anchordoqui, Feng, Goldberg, Shapere (2001)HiRes Collaboration (1994)

January 2003 UCSD Feng 23

• Lower bounds on MD from absence of BHs at AGASA and HiRes for MBH

min = MD .

• For n > 3, MD > 1.5 – 2.0 TeV, most stringent bounds to date

Current Bounds: AGASA, HiRes

Anchordoqui, Feng, Goldberg, Shapere (2001)

January 2003 UCSD Feng 24

For MBHmin ~ 10 MD ,

well into classical regime, bounds are comparable to or exceed all other bounds

MBHmin Dependence

Lower bounds on MD for n=1,...,7 from below

xmin = MBHmin/MD

January 2003 UCSD Feng 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

January 2003 UCSD Feng 26

Comparison with LHC

• LHC predictions extremely sensitive to MBH

min

• No Auger BHs, MBHmin

>5 MD no LHC BHs

• Of course, we could see events! ...

January 2003 UCSD Feng 27

Black Hole Identification

• How will you know if you’ve created one?

January 2003 UCSD Feng 28

S. Harris

January 2003 UCSD Feng 29

BHs vs. SM

• BH rates may be 1000 times SM rate. But

– large BH large rate

– large flux large rate

• However, consider Earth-skimming neutrinos:

– large flux large rate

– large BH small rateBertou et al. (2001)

Feng, Fisher, Wilczek, Yu (2001)

January 2003 UCSD Feng 30

Quasi-horizontal (dashed) and Earth-skimming showers (dotted) in 5 years.

SM explanation (BH=0) excluded at high CL.

January 2003 UCSD Feng 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

• ……

January 2003 UCSD Feng 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)

...

January 2003 UCSD Feng 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

Anchordoqui, Feng, Goldberg, Shapere (2001)

MD (

TeV

)