RandallSundrum Graviton in the diphoton channel

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Randall-Sundrum Gravitonin the diphoton channel

• Marie-Claude Lemaire (DAPNIA, Saclay)
• and
• Vladimir Litvin (Caltech)
• Outline
• Randall-Sundrum model
• Single photon without saturation
• Single photon with saturation correction
• Randall-Sundrum Graviton
• Cuts
• Results
• Conclusion

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Randall Sundrum model
Gravity scale Lp MPlanck exp(-kprc) TeV for
krc 11-12 no hierarchy Graviton resonances mn
xn k exp(-kprc), J1(xn)0 Two parameters control
the properties of the RS model the mass of the
graviton mG and the constant ck/MPlanck
determining the graviton couplings and
widths Stabilization needs to introduce a scalar
field, the radion which generally mixes with the
Higgs
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Properties of Randall-Sundrum Gravitons
Angular distributions
Branching ratios
gg ? G ? gg, gg (c) q qbar ? G ?
gg, gg (a)
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CDF (ICHEP 2004) RS Extra Dimension
ee, mm, gg
Lower limits on MG (GeV) for k/MPL 0.1

• Further improvement can be achieved by
• using mass window method for dilepton channels
• combining channels

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Data samples

• Generation
• Single photons 2k pt 0.25, 0.75 and 1.8 TeV/c
  CMSIM133 and ORCA_8_1_3
• Randall-Sundrum Graviton CMKIN_3_1_0, CMSIM133
  and ORCA_8_1_3
• Angular distributions included in Pythia 6.225
  for the graviton decaying in the diphoton channel
• Reconstruction with ORCA_8_4_0
• Hybrid algorithm in barrel and Island in endcap
• Randall-Sundrum Graviton 2k events MG 1.5 and
  3.5 TeV/c2

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Single photon without saturation
m 0.9996 s 0.007 seff 0.011
m 0.999 s 0.006 seff 0.008
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MGPA saturation correction

• Saturation of MGPA at 1.25 TeV in the barrel if
  6 p.e./MeV).
• It will be a problem for heavy resonances (few
  TeV/c2)
• Use Carolines idea for the saturation correction
  CMS NOTE 2004/024

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Saturation correction

• Saturation at 1250 GeV Fit 0 lt Red_5lt 75 GeV
  S1 12.44 Red_5

photons rms0.128
rms 0.128 for photons was 0.112 for
electrons
electrons rms0112
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Saturation correction for a 4 TeV/c2 Graviton
2 SC with Et gt 150 GeV/c2 trig_hlt_2p 1 or
trig_hlt_r2p 1
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Simple Analysis example MG 1.5 TeV/c2

• 2 SC with Et gt 150 GeV, trig_hlt_2p 1 or
  trig_htl_r2p1
• Calorimeter isolation ctritreria For each SC,
  the energy in a cone of DR 0.5 (excluding the
  SC) should be lt 0.02 ET(SC)
• E(HCAL)/ E(ECAL) lt 0.1
• Tracker isolation criteria For each track
  associated with a Super-Cluster, required that
  the number of tracks of pTgt2.5 GeV in a cone DR
  0.3 (excluding the matched track) should be 0.

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Randall-Sundrum Graviton MG 1.5 TeV/c2
m 1.50 s 0.007
s 0.0067 for electrons
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Signal MG3.5 TeV/c2 and prompt photon bkg
In mass window 2.97-3.92 TeV/c2 Ns 47.1 evts
(k1) Nbkg 20.5 evts (k1.5) Bkg completly
dominated by qqbar prompt photons k factor from
AN2003/009 H -gt gg analysis S 7.4
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Randall-Sundrum Graviton with cteq6l pdf
m 1.498 TeV/c2 s 0.0076 109.6 evts in 3s
mass window was 73.6 for CTEQ5L (x 1.5)
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pdf comparison
cteq6l
cteq5L
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Conclusion

• Simple saturation corrections developed for the
  di-electron chanel
• (CMS NOTE 2004/024) lead to promising results for
  the di-photon
• channel.
• New Tracker isolation is included. It will help
  to reject QCD background
• at lower invariant masses
• New cteq6l LHApdf vs CTEQ5L pdf
• Improvment of the saturation correction has still
  to be studied
• Thanks to Caroline Collard (LLR) and David Futyan
  (UC Riverside and CERN)