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LCD-LCWS

LCD-LCWS. Presentation at the LCWS 2005 Meeting The Importance of Positron Polarization and the Deleterious Effects of Beam/Bremmstrahlung on the Measurement of Supersymmetric Particle Masses and other Parameters March 2005.

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LCD-LCWS

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  1. LCD-LCWS • Presentation at the LCWS 2005 • Meeting • The Importance of Positron Polarization and the Deleterious Effects of Beam/Bremmstrahlung on the Measurement of Supersymmetric Particle • Masses and other Parameters • March 2005

  2. LCD-LCWS • THE POSITRON POLARIZATION GROUP • CERN-PH-TH/2005-036, DCPT-04-100, IPPP-04-50 • G. Moortgat-Pick, et. al.

  3. LCD-LCWS • THE COLORADO GROUP • Lisa Boyle, Shenjian Chen, Bradford Dobos, Keith Drake, • Chris Geraci, Jack Gill, Jason Gray, Andrew Hahn, • Kyle Miller, Martin Nagel, Uriel Nauenberg, • Matthew Phillips, Joseph Proulx, • Will Ruddick, Jesse Smock, Jinlong Zhang

  4. LCD-ILCWS • ACTIVITIES • The Importance of Positron Polarization in • Determining SUSY Masses and other Parameters. • Simulation of Supersymmetry. New method to overcome the negative effects of beamstrahlung and bremmstrahlung.

  5. LCD-LCWS • Positron Polarization Helps Depends on Pol (e+) e + Only from LR, RL e + J=1 Helicities not coupled J=0 e - Only from LL, RR e - Depends on Pol (e -)

  6. LCD-LCWS • electron Left Pol 80% electron Right Pol 80%

  7. LCD-ALCPG   • Electron, Positron Energy Spectrum from e + e -  all e e • e- Spect.e - 80%Re+ Spect.e-Spect.e - 80%Re+ Spect. e+ 80% R e+ 80% L e+ 0 pol. e+ 0 pol.

  8. LCD-ALCPG   • Muon Energy Spectrum from e+ e -  m + m – • e - 80% R e + 80% L e – 80% L e + 80% R   R L WW Bkg WW Bkg

  9. LCD-LCWS • These selectron, smuon signals with • various electron and positron polarization are clear evidence for supersymmetry.!!! • These energy distributions can not be produced with Standard Model processes. • Need positron polarization to observe • dramatic energy distribution shape variations.

  10. LCD-LCWS  • Measurement of the sfermion Mixing Angle ( f ) • Varying the electron and positron polarizations

  11. LCD-LCWS • This is one case where removal of the • 2 g process is crucial • The leptons from stau decays are soft.

  12. LCD-LCWS Mt = 200 GeV Ecm = 500 GeV    • s (e+ e– t1 t1) fb 1 1 1. (b) (a) 0.5 0.5 |cos i| =0.4 |cos i| = 0.66 P+ 0. P+ 0. -0.5 -0.5 1. -1. -1. -0.5 0. 0.5 1. -1. -0.5 0. 0.5 1. P– P–

  13. LCD-LCWS (b) (a) -0.62 0.27 P– = –0.9 L = 500 fb -1 -0.64 0.26 ALR 0.25 cos i -0.66 0.24 -0.68 L=100 fb -1 P– = + 0.9 0.23 -0.70 196 198 200 202 204 -0.67 -0.66 - 0.65 P+ = o mt (GeV) cos i

  14. LCD-LCWS • Measuring the sfermion mixing angle • The sfermion production goes via g, Z exchange in the • s-channel and the coupling constants depend on the • sfermion mixing angle (i ). The cross section can be • enhanced by varying the positron polarization and the • sensitivity on the mixing angle can be determined • more readily and measured.

  15. LCD-LCWS • Study of Chargino and Neutralino Production with Positron Polarization.

  16. LCD-LCWS  +  - • Ecm= 1 TeVs (i j ) fb SPS1a Pe = + 0.9 Pe =- 0.9 - -

  17. LCD-LCWS   • Ecm =1 TeV s (i j )fb SPS1a

  18. LCD-LCWS       s (1 2) X B.R.(2 lR l1) X B.R.( lR l2 10) fb • Define T = {P(e –)X P( l2 )} . P( l1) • A(T) = • ACP = Diff. in Pol. of t • Non-zero AT , ACP CP Violation    s(T > 0 ) - s (T < 0 ) ----------------- s (T > 0 ) + s (T < 0 )

  19. LCD-LCWS • Determined the values of s and A(T) as a function of electron and positron polarization • for the following parameters • M0 = 100 GeV tan(b) = 10 • M2 = 400 GeV (M1) = 0.2p • |At| = 250 GeV (At) = (m)= 0 • |m | = 240 GeV

  20. LCD-LCWS   • s ( 1010 l1 l2) fb AT in % 4 28 -4.5 Pe+ 12 Pe+ 24 -3 20 0 3 24 20 6 28 8 36 12 48 9 4 60 Pe – Pe –

  21. LCD-LCWS   • s (10 t1+t -) fb ACP % -14.5 1 Pe+ Pe+ 30 5 -12 10 25 -6 20 15 0 17 17 6 15 20 12 10 25 13.5 5 30 1 Pe – Pe –

  22. LCD-LCWS   • s ( 10t1+ t - ) fb ACP % 35 5 Pe+ Pe+ 30 -12 10 25 -9 20 15 -6 -3 17 0 17 15 3 10 20 6.5 5 25 Pe – Pe –

  23. LCD-LCWS         • 1020 , 2010 l+l– 3020 , 2010 l+l–

  24. LCD-LCWS • WORD OF CAUTION • All neutralino signals than end in 2 leptons without • a mass constraint (like Z0 ) are overwhelmed by • selectron and sneutrino production channels • because of t-channels and by 2 g channels • specially if the leptons come from t decays. • Needs careful simulation. Playing with positron • polarization should help.

  25. LCD-LCWS • The Effect of Beam-Bremmstrahlung

  26. LCD-LCWS • CM Energy Distribution with Beamstrahlung

  27. LCD-ALCPG • Simulation of Selectron Production Case Study • Consider Case SPS1 , M1/2 = 250 GeV, M0 = 100 GeV. • Mass of eR = 143.11GeV, Mass of eL = 204.6 GeV, Mass of 01 = 95.47 • Compare Fits with Beam and Bremmstrahlung and without. • We use the e+ - e - Energy Spectra Substraction Technique to remove Standard Model Background.

  28. LCD-LCWS • Selectron Production • e+ - e - Energy Spectra

  29. LCD-LCWS • Chi-Square Fits for the SPS1 Snowmass Point • M1/2 = 250 GeV • M0 = 100 GeV • tan( ) fixed at 10

  30. LCD-LCWS • Resultant Fits to Energy Edges • No Bremm Bremm

  31. LCD-LCWS • 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.

  32. LCD-LCWS M1/2 = 400 , M0 = 90 expec. value. M1/2 = – 1.5% from 400, M0 = 90

  33. LCD-LCWS • M1/2 vs M0 curves for Msel L values M1/2 vs M0 curves for Msel R values Not physical Not physical

  34. LCD-LCWS  • M1/2 vs M0 curves for M(c10 ) No dependence on tan( ) Not physical

  35. LCD-ALCPG • Simulation of Selectron, Smuon Production • Case Study • Consider Case SPS3 , M1/2 = 400 GeV, M0 = 90 GeV. • Mass of eR = 179.1 GeV, Mass of eL = 292.5 GeV, Mass of 01 = 158.2 GeV. • Compare Fits with Beam and Bremmstrahlung and without. • For selectrons we use the e+ - e - Energy Spectra Substraction Technique to remove Standard Model Background.

  36. LCD-LCWS • Chi Square Fit for the SPS3 Snowmass Point • M1/2(expec.) = 400 GeV • M1/2(fit)=400.22+0.19GeV • M0 fixed at 90 GeV • tan( ) fixed at 10 -0.54

  37. LCD-ALCPG   • Muon Energy Spectrum from e+ e -  m + m – • e - 80% R e + 80% L e – 80% L e + 80% R   R L WW Bkg WW Bkg

  38. LCD-LCWS nobrem/beamstrahl brem/beamstrahl

  39. LCD_LCWS • SPS3 Point; Ecm =750 GeV ;M1/2 =400 GeV, M0=90 GeV

  40. LCD-LCWS • Resultant Masses from Fits • Input Masses Mass fit E.P. Mas Fit ChiS. • mR 179.1 171.3 179.0 • mL 292.5 287.4 292.0  

  41. LCD-LCWS • Study of Sneutrino Productione • A Very Interesting Case • SPS6 Point • Ecm = 750 GeV • M0 = 150 GeV, M1/2 = 300 GeV • A0 = 0 GeV , tan(b ) = 10 • Mn = 243.8 GeV; Mc = 222.4 GeV • ne c1+ e – ; c1+ c10 W+ ; W+ hadrons   + 1    

  42. LCD-LCWS • Energy Spectrum of Hadronic Jets • after Hadronic Mass (W) Cut cut from SUSY proc. from WW SM process Sneutrino signal

  43. LCD-LCWS • No Beam/Bremmstrahl Beam/Bremmstrahl no beam/bremm SUSY backgnd Effect of beam/ bremmstrahl

  44. LCD-LCWS • Sneutrino Mass Dependence on Parameters M1/2 M0 tan (b ) A0

  45. LCD-LCWS • Chargino Mass Dependence on Parameters M1/2 M0 tan (b ) A0

  46. LCD-LCWS • Chi-Square fits to the Electron Energy Distribution

  47. LCD-LCWS • Resultant Masses from Fits • Input Mass Before Strahl After Strahl ChiS Fit • End Point End Point • ne 243.8 243.6 248.9 243.5 • c1+ 222.4 222 .1 227.4 222 .0

  48. LCD-LCWS • CONCLUSION • The slepton, sneutrino signals are easy to observe and • easy to measure with positron polarization if the 2 photon • process is tagged with excellent efficiency. • The masses depend on all the parameters of the SUGRA • model and hence we can determine consistency of M0 and • M1/2 with high accuracy (~ 0.2%) and determine A0 and • tan (b) .

  49. LCD-LCWS • Neutralino Production Study • e+ e -   0  0 •  Z0 + • Z0  l +l- one decay • Z0  q q other decay  ~ 2 2    0  0 1 2 

  50. LCD-LCWS • Energy Distribution of the Z

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