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TeV-scale gravity: A new window on high-energy physics Marco Cavaglià

Dept. of Physics & Astronomy University of Mississippi

Summers

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Warning

This talk may be monitored for quality purposes (see cameras around) ...so don't even think of falling asleep!

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 2

Hierarchy problem for kids

Observed Planck scale: MPl ~ 1019 GeV

Susy? Running couplings? Observed EW scale: MEW ~ 102 GeV

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 3

The approach "from below"

(Arkani-Hamed, Dimopoulos & Dvali 1998; 1999; Antoniadis, Arkani-Hamed & Dvali 1998)

The space time is D-dimensional (D>4) SM fields are confined on a 3-brane in a higherdimensional space time Only gravity propagates in the n=D-4 extra dimensions

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Brane Universe

M *n + 2 S= d n+ 4 x - g R( g ) 16

Gn +4 = G4Vn

M Pl = M * Vn

2 n+ 2

3-brane

Marco Cavaglià

M* may be very small!!

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

Example:

Randall-Sundrum

(Randall & Sundrum 1999)

Brane (may be fat)

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Horava-Witten

(Horava & Witten 1996)

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Which is the best?

N. Arkani-Hamed, E. Witten & L. Randall at Strings 2002

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 8

Factorizable geometries:

(e.g. Arkani-Hamed, Dimopoulos & Dvali 1998; 1999)

ds 2 = µ dx µ dx v + g ab ( y )dy a dy b

Non-Factorizable geometries:

(e.g. Randall & Sundrum 1999)

ds 2 = e 2 A( y ) µ dx µ dx v + g ab ( y )dy a dy b

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 9

How do we probe extra-dimensions?

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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All depends on M*...

If M* is ~ 1016TeV... ...experimental quantum gravity requires:

Funding unlikely!

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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But

If M* is ~ TeV... ...quantum gravity becomes strong at ~ TeV

This may be enough!

LHC: Center-of-Mass energy = 14 TeV

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 12

or even better...

UHECR: Center-of-Mass energy above 102 TeV!

(Courtesy of Auger project)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 13

Gravitational effects at the TeV scale Perturbative effects (Energy ~ M*) <

(Giudice et al. 1998; Mirabelli et al. 1998; Han et al. 1998; Hewett 1999)

Kaluza-Klein modes Virtual graviton exchange

Nonperturbative effects (Energy > M*) ~

(Banks & Fischler 1999; Amati et al. 1987)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 14

Experimental constraints

Cavendish experiments: n=2, M*>1.6 TeV Particle collider experiments: M*/TeV larger than

(see e.g. Giudice & Strumia 2002; Peskin 2000) (Adelberger et al. 2002)

LEP II Tevatron LHC

n=2 0.90 0.86 9.4

n=4 0.33 0.39 3.4

n=6 0.18 0.27 2.1

Astrophysics and cosmology: M*/TeV larger than

(see e.g. Cullen & Perelstein 1999)

SN1987A Neutron stars CMBR CBR UHECR

Marco Cavaglià

n=2 38-63 1260 65-750 83-263

n=3 2.2-3.9 33 4-32 2.8-7.6 0.2-0.3

n=4 0.45 0.7-4 0.2-0.3

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

Nonperturbative effects:

Scattering of two particles with C-o-M energy larger than ~ TeV and impact parameter b < rs

Black hole forms!

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 16

Can we estimate the cross section of the process?

Yes!!

(At high energies BH formation is semiclassical)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 17

Regimes of gravity

(Giudice, Rattazzi & Wells 2001)

E < M* Perturbative gravitational interactions ~ E ~ M* Quantum gravitational interactions E > M* Semiclassical gravitational interactions ~

Gn + 4

(2 ) n n +1 = n -1 n+ 2 , c M*

Gn +4 L* = 3 c

1 n+ 2

,

4c LB = s

0

Marco Cavaglià

s >> M * RS >> L* >> LB 0

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

Cross section

(Landsberg & Dimopoulos 2001; Giddings & Thomas 2002)

1 8 (( n + 3) / 2 ) bh ( s ; n ) r (2 + n) s*

2 s

2 n +1

s s *

1 n +1

where

M = s

M* = s*

Uncharged, non-rotating, spherically symmetric BH Cross section = black disk (semiclassical regime) Form factor = 1

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 19

If M ~ TeV rs ~ TeV-1

UHECR (neutrino-proton to BH):

p bh ( s ; n )

dx f ( x , Q )

i i

1

bh

( xs ; n )

LHC (proton-proton to BH):

pp bh

( s; n )

ij

dy dx y f i ( y , Q ) f i ( x / y , Q ) bh ( xs ; n ) x

1

1

Muon collider (muon-muon to BH):

µµ bh ( s ; n ) bh ( s ; n )

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 20

Experimental signatures:

Very large and steep cross section

(Landsberg & Dimopoulos 2001; Giddings & Thomas 2002)

Visible transverse energy / High sphericity events

(Giddings & Thomas 2002)

High (?) multiplicity events (hadronic jets + leptons + hard quanta at the end of decay)

(Giddings & Thomas 2002; Cavaglia` 2003)

Ratio of hadronic to leptonic activity ~ 5:1

(Giddings & Thomas 2002; Han et al. 2002; Cavaglia` 2003)

Possible large missing energy Suppression of hard perturbative scattering processes

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 21

(Cavaglia`, Das & Maartens 2003)

Multiplicity of decay products

(Cavaglia` 2003)

n + 1 ( d - 1) M BH i ci (d )i (d , si ) f i (d - 1) N= n + 2 (d - 1) ( d ) TBH j c j (d ) j (d , s j ) f j (d ) Ni = N ci (d )i (d , si ) f i (d - 1) j c j (d ) j (d , s j ) f j (d - 1) .64 spin 2 (10,2) spin1 (4,1)

dEem, grav / dt dEem , spin1 / dt

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Example

M* = 1 TeV, n = 6, MBH = 12 TeV

quark charged l. neutrino Higgs photon 5 1 0 0 0 gluon W Z graviton 1 0 0 0

Quarks and gluon hadronize. H-to-L ratio ~ 5:1

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

Marco Cavaglià

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Cross section uncertainties

Nonrelativistic limit estimates Classical photon capture / plunging estimates

(Berti, Cavaglia` & Gualtieri 2003)

Collisional energy loss/inelasticity

(Yoshino & Nambu, 2003)

Angular momentum corrections

(Yoshino & Nambu 2003)

Charge effects

(Casadio & Harms 2002)

Minimal BH formation mass, thermal fluctuations

(Cavaglia`, Das & Maartens 2003; Cavaglia` & Das, 2004)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 24

Experiments

Particle colliders

(proton-proton or heavy nuclei collisions)

Don't miss E.-J. UHECR detectors Ahn talk on Sunday!

(atmospheric air-showers)

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Colliders:

LHC: Center-of-mass energy (pp) = 14 TeV " " (PbPb) = 5.5 TeV CLIC: Center-of-mass energy = 3 TeV µ-LC: Center-of-Mass energy = 4 TeV VLHC: Center-of-Mass energy = up to 100 TeV VLµC: Center-of-Mass energy = up to 200 TeV

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 26

(Courtesy of CERN)

(Completion date: 2007?)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 27

(Courtesy of CERN)

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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LHC Collision points

(Courtesy of CERN)

Marco Cavaglià

L=1034cm-2s-1

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

LHC detectors

General-purpose Higgs SUSY BHs ??

Heavy Ions Quark-gluon plasma

B-physics CP Violation

Marco Cavaglià

General-purpose Higgs SUSY BHs ??

(Adapted from D. Barney)

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

BH collisions at LHC

Proton 7 TeV Proton 7 TeV

Bunch Crossing 4x107 Hz Proton Collisions 109 Hz Parton Collisions BH Production

Marco Cavaglià

(Adapted from D. Barney)

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14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

BH cross section at LHC

C-o-M= 14 TeV Comparable with pptt n=2..7 from above

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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BH event at CMS

(Model of Landsberg & Dimopoulos, Herwig implementation by C. Harris & P. Richardson, generated by A. de Roeck, simulated & visualized by S. Wynhoff)

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 33

Discovery of the first black hole at LHC

Author's disclaimer: the author of this talk does not assume any responsibility for the incidents portrayed herein

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 34

Brane factories

For a symmetric compactification with n=2, M* ~ 1 TeV

rs ~ TeV-1 ~ 10-15 mm L ~ 0.1 mm

The BH "sees" an isotropic spacetime spherically symmetric What about asymmetric compactifications?

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 35

In asymmetric spaces the scattering of two particles...

(Ahn, Cavaglia` & Olinto 2002)

Marco Cavaglià

14th

Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

... forms branes!

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Brane cross section

(Ahn, Cavaglia` & Olinto 2002; Ahn & Cavaglia` 2002)

2w s 1 - 2 ij br ( s ; p , n , V p ) r ( n , p ) V p n +1 s s* * 2 p

w n +1

where

(n, p ) = ( n + 2 )( n + 2 - p ) 8 p + 1

n + 3- p 2

(

)

w n +1

p w = 1 - n + 1

1 n +1

-1

p = 0 Schwarzschild:

1 2 s ij bh ( s ; n ) ( n , 0 ) s s* *

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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Asymmetric compactifications with brane completely wrapped on L-size dimensions:

- 2p n - p +1 ( w -1 ) n +1

(n, p ) 2 ( s; n, m , p m ) ( n ,0 ) 2

L L *

M M *

2

>1

Brane production dominates black hole production

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 38

LHC = brane factory!!

5-brane BH p=0..5 from below M*=1 TeV, n=7

Marco Cavaglià 14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004 39

Conclusion

Something must happen at E ~ TeV If large extra dimensions exist Planck scale ~ TeV Nonperturbative quantum gravity effects at E ~ TeV Creation of black holes & branes in colliders and in the atmosphere If not, constraints on the Planck scale If yes, new physics at the TeV scale Possible tests of strong gravitational effects

Marco Cavaglià

14th Course of the Int. School of Cosmic Ray Astrophysics, Erice 2004

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