ALCPGVictoria

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ALCPG-Victoria

• Presentation at the ALCPG Victoria
• Meeting
• A New Improved Method to
• Determine SUSY Parameters in the
• Presence of Beam/Bremmstrahlung
• April, 2004

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ALCPG-Victoria

• THE GROUP
• Shirley Choi, Bradford Dobos, Tyler
  Dorland,
• Jeremiah Goodson, Jack Gill, Jason
  Gray,
• Andrew Hahn, Alfonso Martinez, Kyle
  Miller,
• Martin Nagel, Uriel
  Nauenberg,
• Joseph Proulx, Jesse Smock

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ALCPG-Victoria

• ACTIVITIES
• Simulation of Supersymmetry. New method to
  overcome the negative effects of beamstrahlung
  and bremmstrahlung.
• The Benefits of Positron Polarization.
• Resolution on M0 , M1/2 , tan (b) from energy
  spectra measurements.

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ALCPG-Victoria

• Advantages of the New Method
• Measures directly the parameters of the model
  and can
• look for consistency in the parameters
  measured for all
• decay modes.
• Less demanding that cuts do not affect the
  secondary
• particle energy spectrum since the cuts are
  also applied
• to the spectrum with parameters being
  varied.
• The variation of cross-section and branching
  ratios with changes in the paraneters become part
  of the fit.
• The SUSY background from other decays becomes
  part
• of the energy spectrum being fitted.

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• Recall Background from g g-gt e e-

From g g
From selectrons
pt
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• Effect of s and B.R. Variations as
  Parameters Vary

M1/2 300
M1/2 300
M1/2 309
M1/2 276
Energy of Z (GeV)
Energy of Z (GeV)
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• Simulation of Selectron Production 2 Case
  Study
• Consider Case SPS1 , M1/2 250 GeV, M0 100
  GeV.
• Mass of eR 143.11 GeV, Mass of eL 204.65
  GeV,
• Mass of ?01 95.47 GeV.
• Consider Case SPS3 , M1/2 400 GeV, M0 90
  GeV.
• Mass of eR 179.12 GeV, Mass of eL 292.53
  GeV,
• Mass of ?01 158.16 GeV
• Compare Fits with Beam and Bremmstrahlung and
  without.
• We use the e - e - Energy Spectra Substraction
  Technique to remove Standard Model Background.

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• CM Energy Distribution with Beamstrahlung

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• Selectron Production
• e - e - Energy
  Spectra

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• Resultant Fits to Energy Edges Using SPS3 Point
• Mass eR Mass
  eL Mass ?1
• Input Mass 178.33 287.11
  160.55
• No Bremm 178.70.2 287.10.2
  160.80.1
• With Bremm 181.80.3 289.90.3
  163.90.3

0
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ALCPG-Victoria

• New Method to Determine Masses
• Compare Energy Spectrum to those Generated with
  different parameters encompasing the correct one.
• Do a Chi Square Fit to the Spectra Comparison.
• Choose the minimum and determine the masses.

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ALCPG-Victoria

• Typical Electron Energy Comparison SPS3

M1/2 400 , M0 90 expec. value.
M1/2 1.5 from 400, M0 90
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• M1/2 vs M0 curves for Me values M1/2 vs
  M0 curves for Me values

R
L
Not physical
Not physical
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?

• M1/2 vs M0 curves for M (c10 )

No dependence on tan(? )
Not physical
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• Chi-Square Fits for the SPS1 Snowmass Point
• 
  M1/2(expect.)250 GeV
• 
  M0 (expect.)100 GeV
• 
  M1/2 250.000.09 GeV
• 
  M0 100.400.39 GeV
• 
  tan(? ) fixed at 10
• 
  No depend. On tan(b)

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ALCPG-Victoria

• Chi-Square Fits for the SPS1 Snowmass Point
• 
  M1/2 250 GeV
• 
  M0 100 GeV
• 
  tan(? ) fixed at 10
• 
  No depend. on
• 
  tan(b)

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ALCPG-Victoria

• Chi Square Fit for the SPS3 Snowmass Point
• 
  
• 
  M1/2(expec.) 400 GeV
• 
  M0 (expec.) 90 GeV
• 
  M1/2(fit)399.96 0.07 GeV
• 
  M0 (fit) 89.91 0.05 GeV
• 
  tan(? ) fixed at 10
• No
  dependence on tan(b)

399.66

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ALCPG-Victoria

• Resultant Fits to Masses Using ?2 for SPS1 Point
• Beamstrahlung Background Included
• Mass eR Mass
  eL Mass ?1
• Input Mass 143.11 204.65
  95.47
• Chi-Square 143.40.3 204.70.2
  95.50.1

0



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ALCPG-Victoria

• Resultant Fits to Masses Using ?2 for SPS3 Point
• Beamstrahlung Background Included
• Mass eR Mass
  eL Mass ?1
• Input Mass 178.33 287.11
  160.55
• Energy Edge 181.80.3 289.90.3
  163.90.3
• Chi-Square 178.190.04 286.820.06
  160.390.03

0



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• SPS4 Point
• e e - ? ? 2 ? 2
• ? Z0
• Z0 ? l l - one decay
• Z0 ? q q other decay

?

0
0
?
?
? 2
? 1
0
0
?
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ALCPG-Victoria

• Energy Distribution of the Z, SPS4 Point

SUSY Background
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?

• M1/2 vs tan(b) for Values of
  ?2 Masses

0
Not Physical Solution
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• By doing an overall fit to the MSSM
• parameters you can include the effects of
  beamstrahlung and SUSY background in the fit.
• In the case of the Energy Spectra of Neutralinos
• Decay Secondaries there is always
• other SUSY Decay Background

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• Z0 Energy Spectra
  Comparison

I think
M1/2 300 GeV
M1/2 309 GeV
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ALCPG-Victoria

SPS4
M1/2 300 GeV
tan(b) 50
F I T
M1/2 303 9 GeV
- 6
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?
?
?
?

• e e- ? ?20 ?20 ?20? Z0 ?10

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• Dependence of ?20 Mass on tan(? )

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• Fit to Electron Energy Spectra
  
• with Beamstrahlung Background
• SPS6 Point
• (a) Input mass values, (b) No Beamstrahl, (c )
  Beamstrahl
• (a)
  (b) (c )
• n Mass 243.8 GeV 243.6? 0.5
  248.9 0.6
• ?1 Mass 222.4 GeV 222.1 0.6
  227.4 0.4

?

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• Study of the Sneutrino Decay Energy Spectrum
• n -gt e ? 1
• 
  SPS6

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• Electron Energy
  Spectrum

No Beamstrahlung
Beamstrahlung
Background
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• Fit to Z Energy Spectra
• with Beamstrahlung Background
• SPS4 Point
• (a) Input mass values, (b) End point fit, (c )
  Chi-Square fit
• (a)
  (b) (c )
• ?20 Mass 218.1 GeV 226? 2 220
  6
• ?10 Mass 118.2 GeV 126 1
  119 4

?

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• Chi-Square Fit Being Done.

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• Effect of Positron Polarization
• What do we observe if we have positron
• polarization. We studied 80 e -, 80 e.
• Applied to Selectrons and Smuons.

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?
?

• Electron, Positron Energy Spectrum from e e -
  ? all e e, SPS3 Point
• e- Spect.e - 80R e Spect. e-
  Spect.e - 80R e Spect.
  

e 80 R
e 80 L
e 0 pol.
e 0 pol.
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?
?

• Muon Energy Spectrum from e e - ? m m
  
• e - 80 R e 80 L
  e 80 L e 80 R

WW BKGD
WW BKGD
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ALCPG-Victoria

• c2 Fit to Muon Energy Spectrum,
  SPS3 Point
• e - 80 R e 80 L
  e - 80 L e 80 R

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LCD-ALCPG

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