Title: First look at limit setting on GMSB models in the final state with 2 fb-1
1First look at limit setting on GMSB models in the
final state with 2 fb-1
- R. Culbertson, M. Goncharov, Eunsin Lee,
- A. Pronko, D. Toback
- Fermilab, Texas AM University
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
2Outline
- Analysis Introduction
- Progress
- GMSB Signal Acceptance
- 1-DIM Optimization with MetSig
- Expected Cross Section Limits
- Conclusion and Plan
3Dominant Signal Process (GMSB)
- Looking for with low
lifetime - - Both Neutralinos decay in the detector --gt Two
Photons - (Optimal for low
lifetimes)
R. Culbertson, D. Kim, M. Kim, S. Lee, and
D.Toback Search for Anomalous Production of
di-photon MET at CDF and Limits on GMSB Models
(CDF/PRD) Phys.Rev.D71, 031104 (2005),
hep-ex/0410053
D0 Collaboration Search for supersymmetry in
di-photon final states at sqrt(s)1.96 TeV
(D0/PLB) Phys.Lett.B659, 856 (2008),
hep-ex/0710.3946
4Exclusion Region were trying to cover
Delayed Photon Analysis M.Goncharov, V.Krutelyov,
E.Lee, D.Toback and P.Wagner Phys. Rev. Lett 99,
121801 (2007)
Were trying to cover here
5Background Sources
Collision (SM) Background
Non-Collision Background Cosmic and Beam Halo
Triggers, Data Sets and Final Objects with
Preselection requirements
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
6Progress
-
- - Sashas MET Resolution Model (Search for
Anomalous Production of Events in 2
fb-1 of Data) blessed (02/21/08) - CDF NOTE 9184
- - Produced GMSB signal (6000 events) Acceptance
- Example point (
) - - 1-Dim Optimization (MetSig cut) to set limit
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
7- Background Sources
- - QCD events(
) with fake
due to energy mismeasurement - - EWK process with real
- (mostly
, - W(e)pho 44, W(e)jet 17, W(tau)pho
14, W(tau)jet 11 ) - - Non-Collision Backgrounds (PMT spikes,
cosmic rays, beam-halo interaction) - To reduce these backgrounds, we require
events to pass the global event selection, photon
ID , non-collision background rejection, and
cleanup cuts. - CDF note 9184 (R. Culbertson, A. Pronko, M.
Goncharov)
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
8Data Sample and Event Quality
- - Ntuples and Good Runs
- Data Stntuples cdfpstn cdipa(d,h,i,j) ,
cdfpstn bhelb(d,h,i,j) - Goodrun list Up to and including period 11
- V17 with good CAL,
CES, COT (allow COT - degraded period but
require Silicon) - Code Release cdfsoft 6.1.4, Stntuple dev_243
- - Data Sample and Event quality
- Diphoton trigger
- Nvx12 ? 1
- Highest ?PT vertex
- For any vertex Zvxlt60 cm
- Any 2 vertices DZvxlt90 cm
- Vertex re-assignment to minimize MET if Nvxgt1
- 2 leading photons pass tight ID cuts
9Central Photon ID cuts
cuts Tight cuts Loose cuts
Calorimeter fiduciality central central
Photon ET gt13 GeV (7 GeV for pre-selection) gt13 GeV (7 GeV for pre-selection)
CES fiduciality XCESlt21.0 cm 9.0 cmltZCESlt230.0 cm XCESlt21.0 cm 9.0 cmltZCESlt230.0 cm
Average CES ?2 lt20 lt20
Had/Em lt0.0550.00045ET lt0.125
Corrected CalISO lt2.00.02(ET-20) or lt0.1ET if ETlt20.0 GeV lt3.00.02(ET-20) or lt0.15ET if ETlt20.0 GeV
TrkISO lt2.00.005ET lt5.0
N3D N3D0,1 N3D0,1
Trk PT (if N3D1) lt1.00.005ET lt0.25ET
2nd CES cluster (wire or strip) lt0.14ET if ETlt18 GeV lt2.40.01ET if ETgt18 GeV No cut
Phoenix rejection No photons matched to phoenix track No photons matched to phoenix track
10GMSB MC Simulation
- Use Pythia to generate the GMSB signal and
cdfSim(Gen6) to simulate the detector - The EMTiming system is simulated (CDF note 7982)
- - http//hepr8.physics.tamu.edu/elee/EmtimeSimul
.html - Generate Neutralino mass100 GeV and lifetime0
ns with the following parameters fixed on the
minimal GMSB Snowmass Slope SPS 8 with a
neutralino NLSP -
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
11Event Reduction for data and GMSB signal
Cuts Data GMSB MC signal (6000 events) Efficiency (Cumulative) Efficiency (Relative)
Pre-selection (trigger, good run, 2 EM objects) 54,802 5815 96.9 96.9
( photon ID, gt7 GeV ) 54,802 1017 17.0 17.5
PMT spikes 54,796 N/A N/A N/A
Vertex 51,440 969 16.2 95.3
Vertex swap gt13 GeV 35,673 945 15.8 97.5
Phoenix 32,899 921 15.4 97.5
Beam Halo 32,890 921 15.4 100
EMTiming 32,865 921 15.4 100
Trackless muon stub 32,720 916 15.3 99.5
MetSig gt 5.0 34 763 12.7 83.3
? Signal Efficiencies in Pre-selection under Study
Estimated from data
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee
12Met and MetSig Distributions for Data and GMSB MC
Signal
DATA
GMSBMC signal (Not scaled yet)
Under Study
Internal integration limit on 1-dim integrals.
Not a big deal. Can be removed by increasing an
integration limit.
Conventional MetSig MET/?ET Sashas MetSig
log10(1-P(MET)) More info on Sashas MET model
Sashas Blessing Talk on Exotic
Meeting(02/21/08)
13MetSig and MET Distributions for Data and GMSB
MC signal
1495 C.L. Expected Corss Section Limit for MetSig
cut
MetSig Acceptance Expected Bkg Observed x_sec(exp) (fb) x_sec(obs) (fb) x_sec(prod) (fb)
3.0 0.131 0.013 106.6 14.5 120 131 173 162
4.0 0.129 0.013 63.6 8.9 52 93 60 162
5.0 0.127 0.013 48.6 7.5 34 81 42 162
6.0 0.125 0.012 38.0 8.0 25 79 39 162
8.0 0.119 0.012 23.5 5.5 13 66 28 162
9.0 0.106 0.011 18.0 4.5 12 63 39 162
10.0 0.090 0.009 16.0 4.0 11 68 46 162
12.0 0.067 0.007 8.1 2.8 6 69 54 162
- Acceptance of events passed the cut / total
of events(6000) - Acceptance Error 10
- Luminosity 2 fb(-1)
- Luminosity error 6
- x_sec(prod) NLO production cross section
(including k-factor)
15MetSig and x_sec limit plots
- MetSig cut kills most of QCD(Fake MET)
background - Most sensitive at MetSig gt 9.0
16Conclusion and Future Plan
-
- - Considering a number of cuts for
multidimensional optimization - Et(pho1), Ht, M(di-pho), MET, Njet25, JetEt,
IsoTrack, - EWK rejection cuts, etc.
-
- - Produce GMSB signal Acceptance for higher
mass points - (110 GeV - 140 GeV ) with more events
(120,000) -
- - Finishing up reproducing delayed photon PRL
acceptance - - Finished up a preliminary gMettrack
optimization(P. Geffert) but - its clear we need to get rid of more QCD
(DelPhi(met,jet)) cut - in previous analysis)
- - Plan to add MetSig of Sashas Met Model to
new analysis
Search for Heavy, Long-Lived Neutralinos
that decay via
Eunsin Lee