RS1 Graviton Diphoton Decay Study: Status and Plans

1
RS-1 Graviton Diphoton Decay Study Status and
Plans

• Vladimir Litvin, Harvey Newman, Sergei Shevchenko
• Caltech CMS
• Jim Branson, Marco
  Pieri
• UCSD CMS
• Marie-Claude Lemaire
• SACLAY
• Mikhail
  Dubinin
• MSU

2
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
3
Randall-Sundrum Graviton properties
Angular Distributions
Branching Ratios
gg ? G ? gg, gg (c) q qbar ? G ?
gg, gg (a)
4
CDF (ICHEP 2004) RS Graviton Search
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

5
Requested Datasets

• We are requesting the next datasets for the
  official full MC production
• - CMKIN_4_3_0, OSCAR 3_6_5 and ORCA_8_7_1
• Signal (see plot on the next slide)
• c0.01 M1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5
  TeV/c2 1k each
• c0.1 M2.5, 3.0, 3.5, 4.0, 4.5 TeV/c2 1k each
• There are five backgrounds we need to study
• born (MSEL 0, MSUB 18)
• box (MSEL 0, MSUB 114)
• brem (MSEL 0, MSUB 14,29,115)
• QCD (MSEL 1)
• DY (MSEL 0, MSUB 1, MSTP 43 3). We are
  using PHOTOS radiation for Z boson decay - MSTJ
  41 1 was added.
• Reconstruction with ORCA_8_7_1
• Hybrid algorithm in barrel and Island in endcap
  (see CMS Note 2001/034)

6
Discovery plane for RS-1 graviton

7
Table of requested background datasets
8
What was done (without pileup)

• Data production at CERN/Caltech/Lyon
• - CMKIN_4_3_0, OSCAR 3_6_5 and ORCA_8_7_3
• Signal
• c0.01 M1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5
  TeV/c2 1k each
• c0.1 M2.5, 3.0, 3.5, 4.0, 4.5 TeV/c2
  1k each
• 1k events for each background dataset in every
  mass window was produced, and analyzed
• There is no officially approved pileup so far, so
  we did it without pileup. Once pileup will be
  approved, we will redo of the datasets on our CPU
  clusters and will use them, until official data
  will be produced. The influence of pileup for the
  highly energetic photons should be comparable
  with the case of graviton decay to two electrons,
  where less than a 5 effect was observed
• Reconstruction with ORCA_8_7_3
• Hybrid algorithm in barrel and Island in endcap

9
Simple Analysis

• 2 Super-Clusters (SCs) with Et gt 150 GeV,
  trig_hlt_2p 1 trig_hlt_r2p1
• Calorimeter isolation criteria 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 0.025
• Tracker isolation the sum of the energy tracks
  in a cone DR 0.3 around the Super-Cluster
  should be lt 0.3 ET(SC)
• Df p -fSC1-fSC2 lt 0.4 Super-Clusters
  back-to-back.
• No track associated with each Super-Cluster
• Photon energy corrections are done in a simple
  way so far
• For S1 energy lt 1.7 TeV, only simple energy
  dependent part of correction is applied (just a
  shift of the peak in 10 different h bins)
• For S1 energy gt 1.7 TeV, the MGPA saturation
  correction was applied (see Marie-Claude talk on
  parallel session and CMS NOTE 2004/024).Energy
  correction algorithm will be improved by taking
  into account corrections for h and f, including
  the effects of cracks. We will also treat
  saturated and non-saturated photon candidates in
  separate event classes, to improve the discovery
  potential.

10
MG 1500 GeV and c0.01
Number of events for L 30 fb-1
11
Randall-Sundrum Graviton MG 1.5 TeV and c0.01
L 30 fb-1

• m 1.50
• 0.009
• Resolution due to detector
• M 1.467-1.525 TeV/c2
• Ns 21.8 evts

12
MG 3500 GeV and c0.1
Number of events for L 30 fb-1
13
Signal MG3.5 TeV c0.1
L 30 fb-1

• m 3.46
• 0.053
• Resolution due to natural width
• of the resonance
• In mass window
• 3.30-3.62 TeV
• Ns 9.6 evts (k1)

14
Signal backgrounds vs invariant mass
MG 1.5 TeV c0.01
15
Signal backgrounds vs invariant mass
MG 2.5 TeV c0.1
16
Significance c0.01 for L30 fb-1
Born k1.5 Box k1.2
17
Significance c0.1 for L 30 fb-1
Born k1.5 Box k1.2
18
Conclusion

• We presented preliminary results on the discovery
  potential for a RS-1 graviton in the diphoton
  decay mode.
• Speed up in official data production and pileup
  is important, but the first draft of the
  corresponding Physics TDR chapter will be done
  based on our preliminary data. This might be
  changed later when/if official data is produced.
• Saturation correction method (CMS NOTE 2004/024)
  was applied for highly energetic photons and a
  simple energy correction for non-saturated
  photons. This algorithm will be improved taking
  into account more sophisticated energy, h and f
  corrections including cracks, and by treating
  saturated and non-saturated photon candidates in
  separate event-classes to improve the discovery
  potential.
• Confidence Limits for 30 fb-1 c0.01 MG
  1.59 TeV
  c0.1 MG 3.54 TeV
• Confidence Limits for 10 fb-1 c0.01 MG
  1.32 TeV
• 
  c0.1 MG 3.14 TeV
• Plan for Physics TDR Plots of signal and all
  backgrounds for MG 1.5 TeV (c0.01) and 2.5
  TeV/c2 (c0.1) plots of significance for 10, 30
  and 100 fb-1 and discovery plane will be
  contributed to Vol II . A separate part will be
  contributed to Vol I about MGPA saturation
  correction.
• The draft of this Chapter for the Physics TDR is
  in process.