Randall- Sundrum Gravitons and Black Holes at the LHC

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Randall- Sundrum Gravitons and Black Holesat the
LHC

• Kevin Black
• Harvard University
• For the ATLAS and CMS Collaborations

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Outline

• TeV Scale Gravity
• Gravitons
• Black Holes
• Summary

Landsberg
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State of the Standard Model

• Effective model which describes data well
• Accommodates but does not explain
• Fermion masses
• CP-Violation
• Well known fine-tuning, hierarchy, triviality
  problems

?mH2
MPl2
LEP EWWG Winter 2007
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Why Gravity at the LHC

• View Standard Model as effective theory as a low
  energy approximation
• New theory takes over at energy scale comparable
  to the Higgs mass L 1 TeV
• SUSY, Technicolor, Little Higgs, ..
• Perhaps there is no other scale , GUT scale is
  TeV
• Gravity made strong by extra dimensions where
  gravity propagates

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Randall Sundrum Model

• SM fields on one of two 4-dimensional brane in a
  5-D space time
• Graviton can propagate in the bulk
• Kaluza-Klein States on the order of TeV
• Main parameters
• Mass of Graviton
• Curvature parameter ( c k/Mpl)
• Signatures in dilepton, diboson, dijet final
  states

?wk MPl e-kr?
q
l
l
q
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Current Direct Limits
PRL 100, 091802 (2008)
CDF Conference note 9160
Mass limits from 300 900 GeV depending on
coupling
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Dimuon Signature
See Dilepton Talk Later this session

• Two reconstructed muons
• One h lt 2.1
• One with PT gt 24 GeV
• Use angular distribution to discriminate spin
• Main background SM Drell-Yan

c 0.01 c 0.02 c 0.05 c 0.10
10 fb-1 100 fb-1 300 fb-1
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Diphotons

• Branching ratio twice as large as dilepton
• Z doesnt decay into diphotons
• Backgrounds
• Direct Diphoton Production
• Photon Jet
• Dijets (photon misidentification)
• Drell-Yan (missing tracks)
• Two isolated photons
  with ET gt 150 GeV
• Isolated both by calorimeter and tracker

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Dijets
See Dijets talk later this session

• Two jets h lt 1
• Fit invariant mass (leading 2 jets)
• Compare observed/predicted
• Including Systematics
• Jet Energy Scale
• Jet Resolution
• Trigger Prescales
• Radiation

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Black Holes
b lt Rs(E) ? BH forms

• Dimopolous, Landsberg
• Black holes could form if two colliding partons
  have impact parameter smaller than RS
• Partonic Cross-Section given by geometry, total
  cross-section convoluted with PDFS
• Decay by Hawking Radiation
• Demographic Decay
• Spherically Symmetric

E/2
s p RS2
b
E/2
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Black Holes Generator Studies

• CATFISH
• Collider grAviTational FIeld Simulator for black
  Holes

Comput.Phys.Commun.177506-517,2007
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Black Hole CMS I

• Parameters
• Plank Scale 2 TeV
• Black Holes 4 10 TeV
• Signature
• high sphericity
• high SpT
• high multiplicity
• Backgrounds
• tt, W/Z jets, Diboson, multijets
• Selection
• MBH(reco) gt 2 TeV
• Multiplicity gt 4
• Sphericity lt 0.28

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Black Hole CMS II
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ATLAS Black Holes

• Event Selection
• Electron or muon with h lt 2.5, pT gt 50 GeV
• Two approaches (almost identical results)
• SpT gt 2.5 TeV (jets leptons)
• At least 4 jets and lepton pT gt 200 GeV

A n2,m 5-14 TeV
B n4,m 5-14 TeV
C n2,m 8-14 TeV
D n7,m 8-14 TeV
A B C D
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ATLAS Black Holes 2

• Reconstruct the visible mass of the black hole
  from all objects and MET
• Very dramatic signature large signal
  cross-sections

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ATLAS Black Holes 3

• Investigated Event Shapes
• Do give separation with background
• Very different for different parameters

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ATLAS Black Holes 4

• Discovery potential
• S/?B gt 5
• S gt 10
• Discovery possible ranging from
• Few pb for 5 TeV
• 1 fb for 9 TeV

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Summary

• Signatures from Gravitons and Black Holes would
  be dramatic compelling signatures
• RS Gravitons should be observable 5 TeV range
  and quickly observable for 1 TeV masses
• Black holes could be seen to very high masses
  (8-9 TeV) with a few to 30 fb-1 of data
  (depending on parameters)
• For older results go to ATLAS and CMS exotics
  pages
• New ATLAS results expected to be made public few
  months

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Backup
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Graviton Signatures at the LHC
q
g
g
g

• Gravitons couple to momentum tensor (contribute
  to most SM processes)
• Monojets
• Single Vector Boson production
• Dilepton/Dijet/Diboson production
• As resonance
• As non-resonant modification to SM cross-section

q
g
G
G
q
q
V
V
G
q
G
q
q
q
V
l
l
V
q
q
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Backup Dimuon I
Signal Cross-Sections
Drell-Yan Backgrounds others on 10 to 40
times smaller
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Dimuon Backup II
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Dimuon Backup III
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Dimuon backup 4

• Systematics Theory
• QCD and EW Scale 13-17
• PDF 7
• Systematics Experiment
• Misalignment
• Pileup - negligible
• Background Shape 10-15 shift in signficance
• Trigger negligible (normalizations float in fit)
• Magnetic Field negligable

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Dimuon Backup 5
C 0.01
C 0.1
Solid line ideal Dotted long term
alignment Dashed first alignment
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Diphoton Backup I
Diphoton production
Dijet
Drell-Yan
Photon Jet
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Diphoton Backup II
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Diphoton Backup III
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Diphoton Backup 4
Hard Process Scale
PDF Uncertainties
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Dijet Backup
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Sezen Sekmen SUSY 07
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Sezen Sekmen SUSY 07
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CMS Black Hole Backup
PDF Uncertainties
Uncertainty on Signficance 12
Sphericity
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Black Hole Backup
CMS TDR -2006
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Atlas Black Hole backup

• As a function of black hole threshold