1. search for eXtra-Dimensions (XD) and Black Holes at the LHC
CMS
Mini-review:
search for eXtra-Dimensions (XD)
and Black Holes at the LHC
Samir FERRAG
University of Oslo, Norway
ATLAS
Universitetet
i Oslo
32nd International Conference on High Energy Physics
Beijing, China, 2004
S. Ferrag, OSLO

2. maximum of approachesand models
Introduction: motivations for eXtra-Dimensions (XD)
Hierarchy problem:
EW scale << GUT scale << Planck scale (~102 GeV, ~1016 GeV, ~1019 GeV)
Alternative:
1 fundamental scale (~ tens TeV) with 1+3+d time-space structure
New parameters:
number of XD: d, size of each XD MC=1/RC , new Planck scale MP (or MD)…
Existing models classified by:
- Space-time geometry: factorized (flat) or warped[1][2]
- Size of compactified XD: large (eV to keV) or small (TeV), same or different size…
- propagating particles into XDs: gravitons, gauge bosons or all (UXD) [3]
Phenomenological aspects at LHC:
- Low MP : production of gravitons and black holes
- Low GUT scale: violation of the logarithmic behaviour of coupling running (aem.w.S) [4]
- Compactification: every particle allowed in the XD presents Kaluza Klein excitations in 4D
- Strongly warped geometry: new scalar to stabilize the geometry
In flat geometry:
Goal: sensitivity to XD parameters (signatures and results) following a
maximum of approachesand models
S. Ferrag, OSLO

3. Corresponding selection of items
-Flat extra-dimensions:
-Large extra-dimensions: direct and virtual graviton exchange
-TeV-1 extra-dimensions: gauge KK excitations
-Low MP effects: black hole production
-Warped extra-dimensions:
-Randall-Sundrum model: Radion, narrow graviton resonances
Also:
-Higgs boson in the black hole decay
-Gravity-matter interaction in fat brane
-Summary and Conclusion
Abstract:
Abstract:
N.Akchurin, et al Fermilab-FN-0752
Abstract:
C. Macesano, S. Nandi and M.Rujoiu, hep-ph/
C. Macesano, A. Mitov and S. Nandi, hep-ph/
S. Ferrag, OSLO

4. Source of uncertainties Results on gG are also available
Large XD: direct graviton production
Only gravity in n extra-dimensions of eV size (mm) [5]
Signals [6]
Jets + Et, g + Et
Backgrounds
100 fb-1
Sensitivity
Source of uncertainties
Uncertainty in s(Z+jets) affects the sensitivity
Results on gG are also available
S. Ferrag, OSLO

5. Large XD: Virtual graviton exchange
GKK
Signals:[7]
Excess in di-leptons and di-photons mass distribution
Forward-backward asymmetry
Event shape: distribution of gg more central (s-channel)
Sensitivity
PT > 800 GeV
S. Ferrag, OSLO

6. TeV-1 XD: Kaluza Klein (KK) excitations
Gauge bosons allowed in 1 small XD MC~ TeV-1 (2x10-4 fm) [8]
Corresponding KK excitations spectrum in 4D:
4TeV
Z and g KK excitations:[9]
invariant mass reconstruction  up to MC~5.8 TeV
interference with Drell-Yan  up to MC~9.5 TeV
differentiate with Z’  Forward-Backward asymmetry
W KK excitations:[10]
direct observation  up to MC~6 TeV
indirect observation  up to MC~9 TeV
difficult to distinguich from W’
gluon KK excitations:[11]
Excess in the dijet Pt distribution  up to MC~15 TeV
S. Ferrag, OSLO

7. TeV scale gauge unification
MSSM+XD
MGUT~30TeV
(4+2)D, R=1/10 Tev-1
Low GUT scale:
Violation of the expected (MS)SM logarithmic
behaviour of couplings (aem,w,s) [4]
Measurement of aS on a large Pt range by measuring dijets cross section
Mc= 4 TeV
From: [12]
Sensitivity to XD is masked by the uncertainties on the proton structure (PDF) [13]
From Mc~5 TeV (without PDF uncertainties) to less than Mc~2 TeV
S. Ferrag, OSLO

8. Black Holes (BH) Object confined in radius R < RS [14]
~1Hz
 LHC is a Black Hole (BH) factory
Development of a Monte Carlo generator: CHARYBDIS [15]
- evaporation and time evolution
- “grey body” factors (transmission of particles through curved space-time outside horizon)
- Planck phase: few hard jets
Simulation in ATLAS: [16]
- cut on the event shape (sphericity)
- mBH reconstructed for each event
- #XD deduced from TH, mBH and MP (Hawking formula)
S. Ferrag, OSLO

9. Warped geometry: radion in Randall-Sundrum model
Planck brane
SM brane
1 XD with non factorizable geometry: [1]
5-D Planck scale
New physics scale in SM brane: ,
Phenomenology: (Radion) [17]
-scalar field to stabilize the distance between branes [18]
-coupling similar to Higgs, mixes with Higgs ( parameter)
-narrow width
Analysis in ATLAS: [19]
-signal and
-background:
Sensitivity: (30 fb-1)
-1st channel: 1.0 TeV for mf = 600 GeV
-2nd channel: 2.2 TeV (0.6 TeV) for mf = 300 (600 GeV)
S. Ferrag, OSLO

10. Warped Geometry: narrow graviton resonance
KK graviton excitations G(k)
-scale 
-coupling & width: c = k/MPl
-0.01 < k/MPl < 0.1
-mass spectrum:
Golden channel: G(1)  e+e- [20]
Signal:
from gluon fusion
1 – cos4*
from quark annihilation
1 – 3cos2* + 4cos4*
Spin-1 (Z ‘): 1 + cos2*
100 fb-1, mG= 1.5 TeV, c = 0.01
Drell-Yan SM
S. Ferrag, OSLO

11. Higgs boson from the black hole decay[21]
High production rate of BH + democratic decay of BH:
MP ~ 2 TeV and n=3 XDs  sBH = 450 pb  1 light Higgs every 3 sec
Event samples: 50k (100k) of Higgsbb with mH=130 (150) GeV/c2 (Truenoir/Pythia)
CMS full simulation and reconstruction programmes (OSCAR/ORCA)
Unusual kinematics of the BH event: (large total energy, large total Et, high multiplicity of
hard jets, high multiplicity of large Et leptons and large Et Higgs)
b-tagging efficiency decreases with increasing jet energy + Calorimeter resolution
 Additional cuts were developed:
From Higgs decay
Any dijet system
polar angle in Higgs center of mass:
scattering angle for parton subprocess:
separation between the two jets:
S. Ferrag, OSLO

12. Higgs boson in the black hole decay: results
Significance:
mH=130GeV
W/Z
mH=150GeV
mH=130 GeV and For 100 pb-1:
S=8.4s with b-tagging 100% efficient
S=7.4s without b-tagging
mH=150 GeV: (Br(Hbb) = 17% only)
needs 4.8 fb-1 of integrated luminosity for the same significance
S. Ferrag, OSLO

13. Universal eXtra-Dimensions (UXD) in fat brane
Universal extra-dimensions in fat brane:
-gravity in n large XDs of size ~eV to ~keV (~mm to ~mm)
-standard matter in small fraction of size ~TeV of a large XD
Gravity-matter interaction rules in UXD with fat brane: [22]
-KK number is violated in gravity-matter interaction
-gravitation coupling is reduced by the fat brane
-fat brane reduces the dependence on cut-off (MP) in calculations (KK summations)
-the results are valid for a large class of models
Single KK
Pair of KK
MP=5TeV
Phenomenology from KK number violation: [23]
-decay of 1st KK level (stable in universal extra-dimensions)
gravitationnal decay width was computed
-single KK production
Large phase space s^ >2M
Constraint: MP close to M
S. Ferrag, OSLO

14. Universal extra-dimensions in fat brane: single KK
Signal: KK  2 jets+Et [23]
parton+parton parton+ parton*Graviton+parton
MP (TeV)
Ptcut=600 GeV
k=3
100 evts
N=2
N=6
20 evts
Background:
W+2jets, Z+2jets, , multijet+Et
Cuts: large Pt and Et
Ptjet1 ,Ptjet2 > Ptcut and Et > k . Ptcut k=1,2 or 3
Sensitivity: up-to 7 TeV in KK mass (or MC)
Drop fastly with Mp
S. Ferrag, OSLO

15. Summary and Conclusion
Hierarchy problem:
eXtra-Dimensions provide a possible solution and bring down the Planck scale
Sensitivity reach:
invariant mass: ~6 TeV
interference: ~9 TeV
Et: ~9 TeV
...
If they exist at the LHC energies and are like we understand them today (flat or warped
geometry, large or small size XDs,black holes, universal extra-dimensions, dark matter....)
LHC experiments are able to probe them, or put a limit on them at least.
S. Ferrag, OSLO

16. References
[1] L. Randall and R. Sundrum, Phys.Rev.Lett. 83 (1999) 3370 (hep-ph/ )
[2] Arkani-Hamed, Dimopoulos and Dvali Phys.Lett. B429 (1998) 263; I. Antoniadis, PL B246 (1990) 377
[3] C. Macesanu, CD McMullen and S. Nandi PR D66 (2001)
[4] K.R. Dienes, E. Dudas and T. Gherghetta, Nucl.Phys. B537 (1999) 47
[5] Giudice, Rattazzi & Wells, Nucl.Phys. B544 (1999) 3 (hep-ph/ )
[6] L. Vacavant and I. Hinchliffe, J. Phys. G: Nucl. Part. Phys. 27 (2001) 1839
[7] V. Kabachenko, A. Miagkov, A. Zenin ATL-PHYS , O.J.P. Éboli et al., Phys. Rev. D (2000)
[8] I. Antoniadis, PL B246 (1990) 377;J. Lykken and S. Nandi, PL B485 (2000) 224
[9] G. Azuelos and G. Polesello BSM report, Proceedings of Les Houches 2001
[10] G. Polesello et M. Prata EPJDirect (SN-ATLAS )
[11] C.Balazs, M.Escalier, S. Ferrag, B. Laforge, G.Polesello, BSM report, Proceedings of Les Houches 2003
[12] C. Balázs, B. Laforge, Phys.Lett. B525 (2002) 219 (hep-ph/ )
[13] S. Ferrag, Compte rendu des rencontres de Moriond 2003, hep-ph/
[14] Dimopoulos and Landsberg, hep-ph/
[15] CM Harris, P. Richardson and BR Webber, JHEP 0308 (2003) 033 (hep-ph/ :
[16] T. Yamamura, J. Tanaka, S.Asai, J.Kanzaki ATL-PHYS
[17] G. Giudice, R. Rattazzi, J.D. Wells hep-ph/
[18] Goldberger and Wise (PRL 83 (1999) 4922)
[19] G.Azuelos, D. Cavalli, H. Przysiezniak, L. Vacavant SN-ATLAS
[20] B.C. Allanach, K.Odigari, A. Parker, B. Webber JHEP 9 19 (2000)
[21] N.Akchurin, J.Damgov, D.Green, S.Kunori, G.Landsberg, J.Marrafino, R.Vidal, H.Wenzel, W.Wu, Fermilab-FN-0752
[22] C. Macesano, A. Mitov and S. Nandi, hep-ph/
[23] C. Macesano, S. Nandi and M.Rujoiu, hep-ph/
S. Ferrag, OSLO