Out-of-this-World Physics:
From Particles to Black Holes
Greg Landsberg
UCSC HEP Seminar
December 6, 2005
Outline
A Word on Hierarchies
Standard Model: Beauty and the Beast
How to Make Gravity Strong?
Looking for Extra Dimensions…
Production of Black Holes at Accelerators
and in Cosmic Rays
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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N.B. Large Hierarchies Tend to
Collapse...
The eighties
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Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Gravitational Hierarchy Collapse
With thanks to Chris Quigg and the
B44 restaurant in San Francisco
Human Castles in Catalonia
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Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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More Large Hierarchies
Collapse of the Soviet Union
The nineties…
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Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Note: Some Hierarchies are
Surprisingly Stable…
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Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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And Keep in Mind…
Fine tuning (required to keep a large hierarchy
stable) exists in Nature:



Solar eclipse: angular size of the sun is the same as the
angular size of the moon within 2.5% (pure coincidence!)
Politics: Florida recount, 2,913,321/2,913,144 =
1.000061
Numerology: 987654321/123456789 =
8.000000073
(HW Assignment: is it really numerology?)
But: beware the anthropic principle


Fall 2005
Properties of the universe are special because we exist
Don’t give up science for philosophy: so far we have been
able to explain how the universe works entirely by science.
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Hierarchy of the Standard Model
Beauty … and the Beast
RGE evolution
Inverse Strength
Gravitational
Force
EM/Hypercharge
Force
Weak Force
Strong Force
vev
102
MGUT
MPl
1016 1019 E [GeV]
Extra dimensions might get rid of the beast while preserving
the beauty!
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Math Meets Physics
Math physics: some dimensionalities are quite special
Example: Laplace equation in two dimensions has a
logarithmic solution; for any higher number of
dimensions it obeys the power law
Some of these peculiarities exhibit themselves in
condensed matter physics, e.g. diffusion equation
solution allows for long-range correlations in 2Dsystems (cf. flocking)
Modern view in topology: one dimension is trivial; two
and three spatial dimensions are special (properties
are defined by the topology); any higher number is not
Do we live in a special space, or only believe that we
are special?
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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The ADD Model
SM fields are localized on the
(3+1)-brane; gravity is the only
force that “feels” the bulk space
What about Newton’s law?
V r  
1 m1m2
1

MPl2 r
MPl3n 


n2
Fall 2005
1
M   
3 n n  2
Pl
G’N = 1 / MPl[ 3n ]   1/MD2; MD  1 TeV
2
m1m2
r n1
Ruled out for infinite extra
dimensions, but does not apply for
sufficiently small compact ones
V r  
Gravity is fundamentally strong
force, bit we do not feel that as it is
diluted by the volume of the bulk
m1m2
for r  R
n
R r
M Dn 2  M Pl2 R n
More precisely, from Gauss’s law:
1  MPl 


R
2 MD  MD 
2/n
8  1012 m, n  1

0.7 mm, n  2

3 nm, n  3
6  1012 m, n  4
Amazing as it is, but no one has
tested Newton’s law to distances
less than  1mm (as of 1998)
Thus, the fundamental Planck scale
could be as low as 1 TeV for n > 1
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Longitudinal ED
Simultaneously, another
idea has appeared:
Gravitational
Force
Inverse Strength

Real
GUT Scale
EM/Hypercharge
Force
Virtual
Image
Weak Force

MPl=1/GN
Strong Force
L ~ 1 TeV
MZ
Fall 2005
MS
M’Pl
M’GUT
MGUT
logE
Explore modification of the
RGE in (4+n)-dimensions to
achieve low-energy
unification of the gauge
forces [Dienes, Dudas,
Gherghetta, PL B436, 55
(1998)]
To achieve that, allow gauge
bosons (g, g, W, and Z) to
propagate in an extra
dimension, which is
“longitudinal” to the SM
brane and compactified on a
“natural” EW scale:
R ~ 1 TeV-1
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Randall-Sundrum Scenario
Randall-Sundrum (RS) scenario [PRL 83,
3370 (1999); PRL 83, 4690 (1999)]
AdS
+ brane – no low energy effects
+– branes – TeV Kaluza-Klein modes of
graviton
Low energy effects on SM brane are
given by L; for krc ~ 10, L ~ 1 TeV
and the hierarchy problem is solved
naturally
2 kr 
2




AdS5
ds  e
r

k: AdS curvature
SM brane
(  )
Fall 2005
Planck brane
( = 0)
G
x5


 dx dx  r d
2
2
L   M Pl e  kr
Reduced Planck mass:
M Pl  M Pl
8
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Differences Between the Models
TeV-1 Scenario:
ADD Model:
Pro: “Eliminates” the
hierarchy problem by
stating that physics
ends at a TeV scale
Only gravity lives in
the “bulk” space
Size of ED’s (n=2-7)
between ~100 m
and ~1 fm
Black holes at the
LHC and in the
interactions of UHE
cosmic rays
Con: Doesn’t explain
why ED are so large
Pro: Lowers GUT
scale by changing
running of the
couplings
Only gauge bosons
(g/g/W/Z) “live” in
ED’s
Size of ED’s ~1 TeV-1
or ~10-19 m
Con: Gravity is not in
the picture
RS Model:
Pro: A rigorous solution
to the hierarchy
problem via
localization of gravity
Gravitons (and
possibly other
particles) propagate in
a single ED, w/ special
metric
Con: Size of ED as
small as ~1/MPl or
~10-35 m
G
x5
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Kaluza-Klein Spectrum
TeV-1 Scenario:
ADD Model:
Winding modes with
energy spacing ~1/r,
i.e. 1 meV – 100 MeV
Can’t resolve these
modes – they appear
as continuous
spectrum
Gravitational coupling
per mode; many modes
Winding modes with
nearly equal energy
spacing ~1/r, i.e.
~TeV
Can excite individual
modes at colliders or
look for indirect
effects
Mi  M  i r
2
0
E
E
~1 TeV
2
2
RS Model:
“Particle in a box” with
a special metric
Energy eigenvalues
are given by zeroes of
Bessel function J1
Light modes might be
accessible at colliders
M 0  0; M i  M 1 xi x1  M 1 , 1.83M 1 ,
2.66 M 1 , 3.48M 1 , 4.30 M 1 , ...
E
~MGUT
GN for zero-mode;
~1/L for others
…
ge …
Mi
M0
Fall 2005
~MPl
Mi
M1
M0
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Using the ED Paradigm
EWSB from extra dimensions:





Hall, Kolda [PL B459, 213 (1999)] (lifted
Higgs mass constraints)
Antoniadis, Benakli, Quiros [NP B583, 35
(2000)] (EWSB from strings in ED)
Cheng, Dobrescu, Hill [NP B589, 249
(2000)] (strong dynamics from ED)
Mirabelli, Schmaltz [PR D61, 113011
(2000)] (Yukawa couplings from split leftand right-handed fermions in ED)
Barbieri, Hall, Namura
[hep-ph/0011311] (radiative EWSB via tquark in the bulk)
Flavor/CP physics from ED:


Fall 2005
Arkani-Hamed, Hall, Smith, Weiner [PRD
61, 116003 (2000)] (flavor/CP breaking
fields on distant branes in ED)
Huang, Li, Wei, Yan [hep-ph/0101002]
(CP-violating phases from moduli fields
in ED)
Neutrino masses and oscillations from
ED:



Arkani-Hamed, Dimopoulos, Dvali,
March-Russell [hep-ph/9811448] (light
Dirac neutrinos from right-handed
neutrinos in the bulk or light Majorana
neutrinos from lepton number breaking
on distant branes)
Dienes, Dudas, Gherghetta
[NP B557, 25 (1999)] (light neutrinos
from right-handed neutrinos in ED or
ED see-saw mechanism)
Dienes, Sarcevic [PL B500, 133
(2001)] (neutrino oscillations w/o
mixing via couplings to bulk fields)
Many other topics from Higgs to dark
matter
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Tabletop Gravity Experiments
[J. Long, J. Price, hep-ph/0303057]
E.Adelberger et al.
PRL 86, 1418 (2001)
Sub-millimeter gravity
measurements could probe
only n=2 case only within
the ADD model
The best sensitivity so far
have been achieved in the U
of Washington torsion
balance experiment – a hightech “remake” of the 1798
Cavendish experiment

R<
~ 0.16 mm (MD > 1.7 TeV)
Sensitivity vanishes quickly
with the distance –~ can’t
push limits further down
significantly
Started restricting ADD with
2 extra dimensions; can’t
probe any higher number
Ultimately push the
sensitivity by a factor of two
in terms of the distance
No sensitivity to the TeV-1
and RS models
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Astrophysical and Cosmological
Constraints
Supernova cooling due to graviton
emission – an alternative cooling
mechanism that would decrease the
dominant cooling via neutrino emission




Tightest limits on any additional cooling
sources come from the measurement
of the SN1987A neutrino flux by the
Kamiokande and IMB
Application to the ADD scenario [Cullen
and Perelstein, PRL 83, 268 (1999);
Hanhart, Phillips, Reddy, and Savage,
Nucl. Phys. B595, 335 (2001)]:
MD > 25-30 TeV (n=2)
MD > 2-4 TeV (n=3)
Distortion of the cosmic diffuse gamma
radiation (CDG) spectrum due to the
GKK  gg decays [Hall and Smith, PRD
60, 085008 (1999)]:


Fall 2005
MD > 100 TeV (n=2)
MD > 5 TeV (n=3)
Overclosure of the universe, matter
dominance in the early universe
[Fairbairn, Phys. Lett. B508, 335
(2001); Fairbairn, Griffiths, JHEP 0202,
024 (2002)]


MD > 86 TeV (n=2)
MD > 7.4 TeV (n=3)
Neutron star g-emission from radiative
decays of the gravitons trapped during
the supernova collapse [Hannestad
and Raffelt, PRL 88, 071301 (2002)]:


MD > 1700 TeV (n=2)
MD > 60 TeV (n=3)
Caveat: there are many known (and
unknown!) uncertainties, so the
cosmological bounds are reliable only
as an order of magnitude estimate
Still, n=2 is largely disfavored
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
17
Collider Signatures for Large ED
Kaluza-Klein gravitons couple to the
energy-momentum tensor, and therefore
contribute to most of the SM processes
For Feynman rules for GKK see:


[Han, Lykken, Zhang, PRD 59, 105006
(1999)]
[Giudice, Rattazzi, Wells, NP B544, 3
(1999)]
Since graviton can propagate in the bulk,
energy and momentum are not conserved
in the GKK emission from the point of view
of our 3+1 space-time
Depending on whether the GKK leaves our
world or remains virtual, the collider
signatures include single photons/Z/jets
with missing ET or fermion/vector boson
pair production
Graviton emission: direct sensitivity to the
fundamental Planck scale MD
Virtual effects: sensitive to the ultraviolet
cutoff MS, expected to be ~MD (and likely
< MD)
The two processes are complementary
Fall 2005
Real Graviton Emission
Monojets at hadron colliders
q
g
g
g
q
GKK
g
GKK
Single VB at hadron or e+e- colliders
V
GKK
GKK
V
GKK
GKK
V
V
Virtual Graviton Effects
Fermion or VB pairs at hadron or e+e- colliders
f
f
GKK
f
V
GKK
f
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
V
18
L’EPilogue (Large ED)
ee  gG
ee  ZG
Experiment
n=2 n=3 n=4 n=5 n=6 n=2 n=3 n=4 n=5
n=6
Color coding
ALEPH
1.28
0.97
0.78
0.66
0.57
0.12
184 GeV
DELPHI
1.38
1.02
0.84
0.68
0.58
L3
1.02
0.81
0.67
0.58
0.51
OPAL
1.09
0.86
0.71
0.61
0.53
Experiment
ee  tt
ALEPH
1.04
0.81
L3
OPAL
Fall 2005
0.98
1.06
1.15
1.00
0.22
0.17
0.14
189 GeV
0.60
0.38
0.29
0.24
0.21
qq
0.65 0.60
0.53/0.57
0.67 0.62 0.46/0.46 (bb)
0.59 0.56
0.73 0.65
0.56 0.58
0.49
0.69 0.54
0.49
0.62
0.66
ff
gg
1.05
0.84
0.60
0.76
0.84
1.00
0.62
0.66
0.81
0.82
0.83
0.91
0.99
0.84
0.89
0.83
WW
>200 GeV
l=-1
GL
Virtual Graviton Exchange
All limits are in TeV
DELPHI
0.35
ZZ
l=+1
Combined
0.75/1.00 (<189)
0.60/0.76 (ff) (<202)
0.68
0.79
1.0/1.1 (<202)
0.63 1.17/1.03 (<209)
0.74
LEP Combined: 1.2/1.1 TeV
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Monojets: Tainted History
[PL, 139B, 115 (1984)]
•These monojets turned out to be due to
unaccounted background
•The signature was deemed doomed and
nearly forgotten
•It took 20 years for the first successful
monojet analysis at a hadron collider to be
completed (at CDF and DØ)
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Colliders: Graviton Emission
ee  g + GKK at LEP


g + MET final state
MP > 1.4-0.5 TeV (ADLO), for n=2…7
qq/gg  q/g + GKK at the Tevatron






Fall 2005
jets + MET final state
Z()+jets is irreducible background
Challenging signature due to large
instrumental backgrounds from jet
mismeasurement, cosmics, etc.
DØ pioneered this search and set limits
[PRL, 90 251802 (2003)] MP > 1.0-0.6
TeV for n=2…7
Later, CDF achieved slightly better limits
Expected reach for Run II/LHC:
n
MD reach,
Run I
MD reach,
Run II
MD reach,
LHC 100 fb-1
2
1100 GeV
1400 GeV
8.5 TeV
3
950 GeV
1150 GeV
6.8 TeV
4
850 GeV
1000 GeV
5.8 TeV
5
700 GeV
900 GeV
5.0 TeV
Theory:
[Giudice, Rattazzi, Wells, Nucl. Phys. B544, 3 (1999)
and corrected version, hep-ph/9811291]
[Mirabelli, Perelstein, Peskin, PRL 82, 2236 (1999)]
85 pb-1
[PRL 90, 251802 (2003)]
q
g
q
GKK
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Tevatron: Virtual Graviton Effects
f
f
GKK
f
V
Expect an interference with the SM
fermion or boson pair production
V
d 2
d 2SM


d cos q* dM d cos q* dM
a n 
bn 
*


f
cos
q
,
M

f 2 cos q* , M 
1
4
8
MP
MP
GKK
f
Run II, 200 pb-1
High-mass, low |cosq*| tail is a
characteristic signature of LED
[Cheung, GL, PRD 62 076003 (2000)]
Best limits on the effective Planck
scale come from new DØ Run II data:

MPl > 1.1-1.6 TeV (n=2-7)
Combined with the Run I DØ result:

MPl > 1.1-1.7 TeV – tightest to date
Sensitivity in Run II and at the LHC:
Run II, 2 fb-1 LHC, 100 fb-1
e+e- + +gg
1.3-1.9 TeV 6.5-10 TeV
1.5-2.4 TeV 7.5-12 TeV
e+e- + +- + gg 1.5-2.5 TeV 7.9-13 TeV
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
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Interesting Candidate Events
While the DØ data are consistent with the SM, the two highestmass candidates have anomalously low value of cosq* typical
of ED signal:
Event Callas: Mee = 475 GeV, cos* = 0.01 Event Farrar: Mgg = 436 GeV, cos* = 0.03
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
23
TeV-1 Extra Dimensions
Intermediate-size extra
dimensions with TeV-1 radius
Introduced by Antoniadis [PL
B246, 377 (1990)] in the string
theory context; used by Dienes,
Dudas, Gherghetta [PL B436, 55
(1998)] to allow for low-energy
unification


Expect ZKK, WKK, gKK resonances
at the LHC energies
At lower energies, can study
effects of virtual exchange of the
Kaluza-Klein modes of vector
bosons
Antoniadis, Benaklis, Quiros [PL B460, 176 (1999)]
ZKK
Current indirect constraints come
from precision EW measurements:
1/r ~ 6 TeV
No dedicated experimental
searches at colliders to date
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
24
First Dedicated Search for TeV-1
Extra Dimensions
200 pb-1, e+eEvent
Callas
Interference effect
1/R = 0.8 TeV
While the Tevatron sensitivity is
inferior to indirect limits, it explores
the effects of virtual KK modes at
higher energies, i.e. complementary
to those in the EW data
DØ has performed the first dedicated
search of this kind in the dielectron
channel based on 200 pb-1 of Run II
data (ZKK, gKK  e+e-)
The 2D-technique similar to the
search for ADD effects in the virtual
exchange yields the best sensitivity in
the DY production [Cheung, GL, PRD
65, 076003 (2002)]
Data agree with the SM predictions,
which resulted in the following limit:


Fall 2005
1/R > 1.12 TeV @ 95% CL
R < 1.75 x 10-19 m
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
25
Randall-Sundrum Model
Observables
Need only two parameters to
define the model: k and rc
Equivalent set of parameters:


The mass of the first KK mode,
M1
Dimensionless coupling k / MPl
To avoid fine-tuning and nonperturbative regime, coupling
can’t be too large or too small
0.01 ≤ k / MPl≤ 0.10 is the
expected range
Gravitons are narrow
Expected Run II
sensitivity in DY
k / MPl
Drell-Yan at the LHC
M1
Davoudiasl, Hewett, Rizzo [PRD 63, 075004 (2001)]
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
26
First Search for RS Gravitons
Already better limits than sensitivity for Run II,
as predicted by phenomenologists!
[PRL 95, 091801 (2005)]
Assume fixed K-factor of 1.3 for the signal
The tightest limits on RS gravitons to date
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
27
Black Holes on Demand
NYT, 9/11/01
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
28
Black Holes in General Relativity
Black Holes are direct prediction of Einstein’s general
relativity theory, established in 1915 (although they
were never quite accepted by Einstein!)
In 1916 Karl Schwarzschild applied GR to a static
non-spinning massive object and derived famous
metric with a singularity at a Schwarzschild radius
r = RS  2MGN/c2 :
Albert Einstein
space
} time
If the radius of the object is less than RS, a black hole
with the event horizon at RS is formed
The term “black-hole” was introduced only around
1967 by John Wheeler
Fall 2005
Karl Schwarzschild
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
29
Black Hole Evolution
Naїvely, black holes would only grow once they are formed
In 1975 Steven Hawking showed that this is not true
[Commun. Math. Phys. 43, 199 (1975)], as the black hole
can evaporate by emitting pairs of virtual photons at the
event horizon, with one of the pair escaping the BH gravity
These photons have a perfect black-body spectrum with the
Hawking temperature:
c
TH 
4 kRS
Stephen Hawking
In natural units ( = c = k = 1), one has the
following fundamental relationship: RSTH = (4)1
If TH is high enough, massive particles can also
be produced in evaporation
Information paradox: if we throw an encyclopedia
in a black hole, and watch it evaporating, where
would the information disappear?
This paradox is possibly solved in the only
quantum theory of gravity we know of: string
theory
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
30
Black Hole Evaporation
As the BH evaporates, its
mass becomes smaller, RS
decreases, and Hawking
temperature increases
Consequently, as the BH
evolves, the radiation
spectrum becomes harder
and harder, until the BH
evaporates completely in a
giant flash of light
Ergo, the BH spends most of
its time at the lowest
temperature, when the
radiation is soft
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
31
Looking for Black Holes
While there is little doubt that BHs exist,
we don’t have an unambiguous evidence
for their existence so far
Many astronomers believe that quasars
are powered by a BH (from slightly above
the Chandrasekhar limit of 1.5 M to
millions of M), and that there are
supermassive (~106 M) black holes in
the centers of many galaxies, including
our own
The most crucial evidence, Hawking
radiation, has not been observed
(TH ~ 100 nK, l ~ 100 km, P ~ 10-27 W:
~1014 years for a single g to reach us!)
The best indirect evidence we have is
spectrum and periodicity in binary
systems
Astronomers are also looking for “flares”
of large objects falling into supermassive
BHs
LIGO/VIRGO hope to observe
gravitational waves from black hole
collisions
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
32
Theoretical Framework
Based on the work done with Dimopoulos
two years ago [PRL 87, 161602 (2001)] and
a related study by Giddings/Thomas [PRD
65, 056010 (2002)]
Extends previous theoretical studies by
Argyres/Dimopoulos/March-Russell [PL
B441, 96 (1998)], Banks/Fischler [JHEP,
9906, 014 (1999)], Emparan/Horowitz/Myers
[PRL 85, 499 (2000)] to collider
phenomenology
Big surprise: BH production is not an exotic
remote possibility, but the dominant effect!
Main idea: when the c.o.m. energy reaches
the fundamental Planck scale, a BH is
formed; cross section is given by the black
disk approximation:
2
 ~ RS ~ 1 TeV
2
~ 10
2
m ~ 100 pb
M2 = ^s
parton
RS
Fall 2005
38
parton
Geometrical cross section approximation
was argued in early follow-up work by
Voloshin [PL B518, 137 (2001) and PL B524,
376 (2002)]
More detailed studies showed that the
criticism does not hold:





Dimopoulos/Emparan – string theory
calculations [PL B526, 393 (2002)]
Eardley/Giddings – full GR calculations for
high-energy collisions with an impact
parameter [PRD 66, 044011 (2002)]; extends
earlier d’Eath and Payne work
Yoshino/Nambu - further generalization of the
above work [PRD 66, 065004 (2002); PRD 67,
024009 (2003)]
Hsu – path integral approach w/ quantum
corrections [PL B555, 29 (2003)]
Jevicki/Thaler – Gibbons-Hawking action used
in Voloshin’s paper is incorrect, as the black
hole is not formed yet! Correct Hamiltonian
was derived: H = p(r2 – M)  ~ p(r2 – H),
which leads to a logarithmic, and not a powerlaw divergence in the action integral. Hence,
there is no exponential suppression [PRD 66,
024041 (2002)]
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
33
Assumptions and Approximation
Fundamental limitation: our lack of knowledge of quantum
gravity effects close to the Planck scale
Consequently, no attempts for partial improvement of the
results, e.g.:



Grey body factors
BH spin, charge, color hair
Relativistic effects and time-dependence
The underlying assumptions rely on two simple qualitative
properties:


The absence of small couplings;
The “democratic” nature of BH decays
We expect these features to survive for light BH
Use semi-classical approach strictly valid only for MBH » MP;
only consider MBH > MP
Clearly, these are important limitations, but there is no way
around them without the knowledge of QG
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
34
Black Hole Production
Schwarzschild radius is given by Argyres
et al., hep-th/9808138 [after Myers/Perry, [Dimopoulos, GL, PRL 87, 161602 (2001)]
Ann. Phys. 172 (1986) 304]; it leads to:
tot = 0.5 nb
2
(MP = 2 TeV, n=7)

 n  3   n 1
8



1  M BH  2  
2
2

( sˆ  M BH )  RS  2 
MP  MP
n2 
LHC


n=4


Hadron colliders: use parton luminosity
tot = 120 fb
w/ MRSD-’ PDF (valid up to the VLHC
(MP = 6 TeV, n=3)
energies)
d pp  BH  X 
dL

ˆ ab  BH  sˆ  M 2
BH
dM BH
dM BH
dL
2M BH

dM BH
s
2
 M BH
dxa
f a xa  f b 
xa
 sxa
1
 
a ,b M 2
BH



s
Note: at c.o.m. energies ~1 TeV the
dominant contribution is from qq’
interactions
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
35
Black Hole Decay
Hawking temperature: RSTH = (n+1)/4
(in natural units  = c = k = 1)
BH radiates mainly on the brane
[Emparan/Horowitz/Myers, hepth/0003118]



l ~ 2/TH > RS; hence, the BH is a point
radiator, producing s-waves, which
depends only on the radial component
The decay into a particle on the brane
and in the bulk is thus the same
Since there are much more particles on
the brane, than in the bulk, decay into
gravitons is largely suppressed
[Dimopoulos, GL, PRL 87, 161602 (2001)]
Note that the formula for N is
strictly valid only for N » 1 due
to the kinematic cutoff E < MBH/2;
If taken into account, it increases
multiplicity at low N
Democratic couplings to ~120 SM d.o.f.
yield probability of Hawking evaporation
into g, l±, and  ~2%, 10%, and 5%
respectively
Averaging over the BB spectrum gives
average multiplicity of decay products:
N 
Fall 2005
M BH
2TH
Stefan’s law: t ~ 10-26 s
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
36
Black Hole Factory
[Dimopoulos, GL, PRL 87, 161602 (2001)]
Black-Hole Factory
n=2
n=7
Drell-Yan
g+X
Spectrum of BH produced at the LHC with subsequent decay into final states
tagged with an electron or a photon
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
37
Shape of Gravity at the LHC
log TH  
1
log M BH  const
n 1
[Dimopoulos, GL, PRL 87, 161602 (2001)]
Relationship between logTH and logMBH allows to find the number of ED,
This result is independent of their shape!
This approach drastically differs from analyzing other collider signatures
and would constitute a “smoking cannon” signature for a TeV Planck scale
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
38
Black Hole Events
First studies already initiated by ATLAS and CMS


ATLAS –CHARYBDIS HERWIG-based generator with more
elaborated decay model [Harris/Richardson/Webber]
CMS – TRUENOIR [GL]
Simulated black hole event in the
Simulated black hole event in the
ATLAS detector [from ATLAS-Japan Group] CMS detector [A. de Roeck & S. Wynhoff]
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
39
Black Holes in the Cosmic Rays
Discussed by Feng/Shapere [PRL 88
(2002) 021303]; Anchordoqui/ Goldberg
[hep-ph/0109242]; Emparan/
Massip/Rattazzi [hep-ph/0109287], …
Proton primaries have very high SM
interaction rate; consider BH production
by quasi-horizontal UHE neutrinos
MBH = 1 TeV, n=1-7
Detect them, e.g. in the Pierre Auger
fluorescence experiment or AGASA
A few to a hundred BHs can be
detected before the LHC turns on
Might be possible to establish the
uniqueness of the signature by
comparing several neutrino-induced
processes
Auger, 5 years of running
[Feng & Shapere, PRL 88 (2002) 021303]
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
40
New Physics in BH Decays
Example: Higgs with the mass of 130 GeV decays predominantly into a bb-pair
Example: 130 GeV Higgs boson – tag BH events with leptons or photons, and
look at the dijet invariant mass; does not even require b-tagging!
Use typical LHC detector response to obtain realistic results
 = 15 nb
MP = 1 TeV, 1 LHC-hour (!)
W/Z
h
t
GL, PRL 88, 181801 (2002)
Fall 2005
boost
t
W
Higgs observation in the black hole
decays is possible at the LHC as early
as in the first day of running even with
the incomplete and poorly calibrated
detectors!
For MP = 1, 2, 3, and 4 TeV one needs
1 day, 1 week, 1 month, or 1 year of
running to find a 5 signal
Higgs is just an example – this applies
to most of the new particles with the
mass ~100 GeV
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
41
Conclusions
http://www.extradimensions.com
On 2/15/00 patent 6,025,810 was issued to David
Strom for a "hyper-light-speed antenna." The
concept is deceptively simple: "The present
invention takes a transmission of energy, and
instead of sending it through normal time and
space, it pokes a small hole into another
dimension, thus sending the energy through a
place which allows transmission of energy to
exceed the speed of light." According to the
If you
still"allows
thinkenergy
that gravity
is
patent,
this portal
from another
weak force,
you plant
maygrowth."
be spending
dimension
to accelerate
too
much
time
in the
lab!
from the
AIP’s
“What’s
New”,
3/17/00
Fall 2005
Stay tuned – next generation of
collider experiments has a good
chance to solve the mystery of
large extra dimensions!
If large extra dimensions are
realized in nature, black hole
production at future colliders is
likely to be the first signature for
quantum gravity at a TeV
Many other exciting
consequences from effects on
precision measurements to
detailed studies of quantum
gravity
If any of these new ideas is
correct, we might see a true
“Grand Unification” – that of
particle physics, astrophysics and
cosmology – in just a few years
from now!
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
42
Universal Extra Dimensions
The most “democratic” ED model: all the SM fields are free to propagate in extra
dimension(s) with the size Rc = 1/Mc ~ 1 TeV-1 [Appelquist, Cheng, Dobrescu,
PRD 64, 035002 (2001)]


Instead of chiral doublets and singlets, model contains vector-like quarks and leptons
Gravitational force is not included in this model
The number of universal extra dimensions is not fixed:


it’s feasible that there is just one (MUED)
the case of two extra dimensions is theoretically attractive, as it breaks down to the
chiral Standard Model and has additional nice features, such as guaranteed proton
stability, etc.
Every particle acquires KK modes with the masses Mn2 = M02 + Mc2, n = 0, 1, 2, …
Kaluza-Klein number (n) is conserved at tree level, i.e. n1  n2  n3  … = 0;
consequently, the lightest KK mode cold be stable (and is an excellent dark matter
candidate [Cheng, Feng, Matchev, PRL 89, 211301 (2002)])
Hence, first level KK-excitations are produced in pairs, similar to SUSY particles
Consequently, current limits (dominated by precision electroweak measurements,
particularly T-parameter) are sufficiently low (Mc ~ 300 GeV for one ED and of the
same order, albeit more model-dependent for >1 ED)
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
43
UED Phenomenology
Naively, one would expect large
clusters of nearly degenerate
states with the mass around 1/RC,
2/RC, …
Cheng, Feng, Matchev, Schmaltz:
not true, as radiative corrections
tend to be large (up to 30%); thus
the KK excitation mass spectrum
resembles that of SUSY!
Minimal UED model with a single
extra dimension, compactified on
an S1/Z2 orbifold

Fall 2005
Q, L (q, l) are SU(2) doublets
(singlets) and contain both
chiralities
[Cheng, Matchev, Schmaltz, PRD 66, 056006 (2002)]
MC = 1/RC = 500 GeV
Odd fields do not have 0 modes,
so we identify them w/ “wrong”
chiralities, so that they vanish in
the SM
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
44
UED Spectroscopy
First level KK-states spectroscopy
[CMS, PRD 66, 056006 (2002)]
Decay:
B(g1→Q1Q) ~ 50%
B(g1→q1q) ~ 50%
B(q1→qg1) ~ 100%
+
B(t1→W1b, H1 b) ~
B(Q1→QZ1:W1:g1) ~ 33%:65%:2%
B(W1→L1:1L) = 1/6:1/6 (per flavor)
B(Z1→1:LL1) ~ 1/6:1/6 (per flavor)
B(L1→g1L) ~ 100%
B(1→g1) ~ 100%

±
B(H1 →gg1, H *g1) ~ 100%
Production:
q1q1 + X → MET + jets (~had/4); but:
low MET
Q1Q1+ X→ V1V’1 + jets → 2-4 l + MET
(~had/4)
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
45
Production Cross Section
Reasonably high rate up to M ~ 500 GeV
Q1Q1, q1q1
Run II, s = 2 TeV
[Rizzo, PRD 64, 095010 (2001)]
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
46
Sensitivity in the Four-Lepton Mode
Only the gold-plated 4leptons + MET mode has
been considered in the
original paper
Sensitivity in Run IIb can
exceed current limits
Much more promising
channels:


dileptons + jets + MET +
X (x9 cross section)
trileptons + jets + MET +
X (x5 cross section)
Detailed simulations is
required: would love to
see this in, e.g. PYTHIA
One could use SUSY
production with adjusted
masses and branching
fractions as a quick fix
Fall 2005
[Cheng, Matchev, Schmaltz, PRD 66, 056006 (2002)]
L is per experiment;
(single experiment)
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
47
A Word on Anthropic Principle
From Merriam-Webster Dictionary, 2020 ed.
Main Entry: an·throp·ic prin·ci·ple
Pronunciation: an-'thrä-pik prin(t)-s(&-)p&l
Function: noun
Etymology: Greek anthrOpikos, from anthrOpos bad science
: A pseudoscientific view of the first decade of the XXI
century related to the explanation of the ‘unlikeliness’
of the Universe not via fundamental laws of nature, but
due to the existence of human life in it. Particularly
popular in the Bible-Belt states along with creationism.
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
48
Fine Tuning Explained…
Fine tuning explained:

Numerology: 987654321/123456789 =
8.000000073 ?
Numerology it is not!
NML... 987654321
lim
N2
N  123456789...LMN

Seeing is believing:
In hexadecimal system,
FEDCBA987654321/123456789ABCDEF =
14.000000000000000183
Fall 2005
Greg Landsberg - Out-of-this-World Physics: From Particles to Black Holes
49