Full Simulation (Jupiter/MarlinReco) of Tau-pair/SUSY mode

Taikan Suehara, The 6th General Meeting of the ILC Physics Working Group, 2008/09/06 page 1

Full Simulation Full Simulation (Jupiter/MarlinReco) of(Jupiter/MarlinReco) ofTau-pair/SUSY modeTau-pair/SUSY mode

Taikan Suehara

ICEPP, The Univ. of Tokyo


• Topics– Tau-pair– SUSY 4-jet mode– SUSY smuon mode

• Motivation– Detector optimization

• Obtain performance of each benchmark mode• Compare performance in various geometries

– GLD (large, 3T), GLD’ (medium, 3.5T), J4LDC (small, 4T)

– Physics• Detection of tau-pair anomalous coupling (Z’ etc.)• SUSY/LHT/scalar particles detection/distinction

Topics/MotivationTopics/Motivation


SUSY 4-jet-modeSUSY 4-jet-mode


• Point 1 smuon -> mu x01• Point 5 neutralino (x02) / chargino

– Chargino/neutralino decay to W/Z+LSP

SUSY parametersSUSY parameters


• Qqbar 4jet events, 130(chargino),30(neutralino) fb• 500 fb-1 with full simulation• Chargino/neutralino must be separated by

identifying daughter W/Z.• Main BG: SM WW -> 4 jets (10000 fb)

SUSY jet modeSUSY jet mode


Cut statistics (1)Cut statistics (1)Process SM 4jet

Geometry GLD GLD' LDC GLD GLD' LDC LDC'Cross section 10000 fbLuminosity 10 fb-1J et events 73310 72572 73263 13923 13930 13929 101905

MC 4jet events 36546 36206 36550 7948 7948 7948 -eL < 20GeV 47700 46591 46893 11604 11602 11586 83968jet angle <0.9 36748 35921 35937 9295 9287 9225 21419all jet > 5GeV 34935 34480 34436 8711 8706 8663 21413Evis < 300GeV 34935 34480 34436 8711 8706 8663 682

Chargino Neutralino

158 fb 29 fb500 fb-1

• # of SM events becomes comparable to chargino after these

cuts.


W/Z mass peak – best W/Z mass peak – best combinationcombination

Cut condition– Same cut as

previous slide– Best-W combination

for chargino events,Best-Z combinationfor neutralino events(minimum 2 combination, 1 width is set to 5 GeVfor both W and Z)

• Peak shift corrected (by adding 0.8 GeV to all jets).


22 distribution / mass cut distribution / mass cut


Cut statistics (2)Cut statistics (2)Process SM 4jet

Geometry GLD GLD' LDC GLD GLD' LDC LDC'Cross section 10000 fbLuminosity 10 fb-1J et events 73310 72572 73263 13923 13930 13929 101905

MC 4jet events 36546 36206 36550 7948 7948 7948 -Cuts after (1) 34935 34480 34436 8711 8706 8663 682

cos(theta_W)<0.8 24897 24595 24672 7069 7100 7068 170acop_w > 10deg 21293 20977 21043 5003 4985 4990 35(MC 4jet in it) 15980 15889 15903 - - - -W mass cut 5022 4908 4985 180 199 189 2

(MC 4jet in it) 4999 4897 4972 - - - -MC 4jet efficiency 13.68% 13.53% 13.60% - - - -

BG acception - - - 1.29% 1.43% 1.36% 0.00%Cuts after (1) 34935 34480 34436 8711 8706 8663 682

cos(theta_Z)<0.8 24648 24342 24425 7034 7108 7045 171(MC 4jet in it) - - - 4870 4946 4896 -Z mass cut 187 210 210 1308 1364 1346 8

(MC 4jet in it) - - - 1303 1360 1339 -MC 4jet efficiency - - - 16.39% 17.11% 16.85% -

BG acception 0.26% 0.29% 0.29% - - - 0.01%

Chargino Neutralino

158 fb 29 fb500 fb-1

• BG separation is efficient (see W/Z mass cut rows)• Slightly better BG separation performance in GLD

but almost within statistical fluctuations.

charg

ino

neu

tralin

o


• SUSY mass is determined by kinematics– Daughter W/Zs have characteristic energy

distribution

• Fitting function:– For neutralino: erf(left) x erfc(right)– For chargino: erf(left),

conbolution of linear and erfc for right

• Generator-level energy distributions (by Akiya):

Mass fit of chargino/neutralinoMass fit of chargino/neutralino

Chargino (W) Neutralino (Z)


Chargino MC cut vs nocutChargino MC cut vs nocut

Very slight shift (left edge?)


Chargino MC vs RecoChargino MC vs Reco

Mass cut by 80 GeV WSlightly shifted?


Mass fit of charginoMass fit of chargino

Fitting seems not so bad.Difference in distribution is within statistical fluctuation.


• Convolution of 3rd pol and Gaussian• Partly cheated

– 1. LSP/chargino mass fixed to input values, fit other 5 parameters– 2. 5 parameters fixed, mass fitted.

Another fittingAnother fitting


• Flat distribution around the top

Neutralino reco/MCNeutralino reco/MC


Mass fit neutralinoMass fit neutralino

Distribution in LDC is slightly broader (worse resolution).Chargino background might not be negligible for lower edge.


• Point 5 chargino/neutralino pair is examined.– Mass resolution < 1 GeV can be obtained

by 500 fb-1 statistics– SM WW background can be removed

efficiently– W/Z separation for chargino/neutralino

separation can be effective in current detector geometry.

SUSY-jet conclusionSUSY-jet conclusion


SUSY lepton modeSUSY lepton mode


• Smuon : 123 GeV, LSP: 97 GeV• Edge of the energy distribution is sharp enough• More background / muon ID efficiency can be examined.

SmuonSmuon


• No difference.

Smuon – reco - MCSmuon – reco - MC


• Point 1 smuon analysis was performed.• Clear edge can be seen

SUSY-smuon conclusionSUSY-smuon conclusion


Tau-pair modeTau-pair mode


• Event characteristics– Sqrt(s) = 500 GeV, including ISR/FSR– 2 jets,1 or 3 prongs/jet, very condensing

(taus in 500 GeV beam are highly boosted)– Cross section is large, ~2.3 pb-1

• Observables, total and differential cross section

– AFB, forward-backword asymmetry

– Apol, polarization asymmetry (paticularly in polarized beams)

• Background and Statistics– Background: bhabha (34000 pb), -> (1500 pb)– Signal: 20 fb-1 (~46000 events)– Bhabha: 0.2 fb-1 preselected full-simulated events -> 0.7 fb-1 generator info

Tau-pair eventsTau-pair events

Typical event


Decay modes in ADecay modes in Apolpol analysis analysis


Analysis flowAnalysis flow

PFO particles

Jets

No

Yes 8.6%

7.0%


• Bhabha and ggtt background can be effectively suppressed

• Statistics in Jupiter will be improved to 20fb-1by Cambridge

Background suppressionBackground suppressionProcess Bhabha ggtt

Geometry GLD GLD' J 4LDC LDC' GLD GLD' J 4LDC LDC' GLD' stdhepCross section (pb) 2.48 2.48 2.48 2.48 2.12 2.12 2.12 2.12 34000 1500Luminosity (fb-1) 9.785081 10.01371 10.0125 20.16129 9.315566 9.905189 9.826415 19.81132 0.2 0.7

All events 24267 24834 24831 50000 19749 20999 20832 42000 13M 1M1+1 jet 16467 16428 17344 35511 13219 13710 14378 29844 - -

jet angle > 170 deg 7130 7161 7269 14377 5910 6210 6231 12079 - 217431|cos(theta)| <0.9 6198 6262 6244 12387 5131 5441 5398 10401 11171 130# of track <= 6 6187 6253 6235 12359 5124 5429 5388 10376 11171 -

ee veto 5825 5882 5860 11728 4850 6109 5066 9846 13 -mumu veto 5602 5652 5630 11239 4662 4899 4855 9451 13 -

40 GeV < Evis < 450 GeV 5541 5579 5564 11010 4587 4833 4784 9252 5 0AFB cut efficiency 22.83% 22.47% 22.41% 22.02% 23.23% 23.02% 22.96% 22.03% 0.4 ppm 0.00%

Tautau-eL(80%) Tautau-eR(80%)


Tau ATau AFBFB result result

SM calculation(Red: left, Blue: right)

ProcessGeometry GLD GLD' J 4LDC LDC' GLD GLD' J 4LDC LDC'

Cross section (pb) 2.48 2.48 2.48 2.48 2.12 2.12 2.12 2.12Luminosity (fb-1) 9.785081 10.01371 10.0125 20.16129 9.315566 9.905189 9.826415 19.81132AFB cut efficiency 22.83% 22.47% 22.41% 22.02% 23.23% 23.02% 22.96% 22.03%

AFB value 47.48% 46.66% 47.45% 48.11% 44.50% 44.59% 44.94% 44.21%AFB error 1.18% 1.18% 1.18% 0.83% 1.32% 1.29% 1.29% 0.93%

AFB error (500fb-1) 0.17% 0.17% 0.17% 0.17% 0.18% 0.18% 0.18% 0.19%



• Clear difference– LDC’ best

• Due to granularity?

– GLD next– J4LDC worst

Rho and pi0 reconstructionRho and pi0 reconstruction


• Worse tau->rhonu efficiency in J4LDC:due to the worse reconstruction of pi0

• Need to be checked in more detail.(esp. for LDC’)

• eR efficiency in rhonu mode is worse:due to low energy cut

Cut efficiencyCut efficiencyProcess

Geometry GLD GLD' J 4LDC LDC' GLD GLD' J 4LDC LDC'Cross section (pb) 2.48 2.48 2.48 2.48 2.12 2.12 2.12 2.12Luminosity (fb-1) 9.79 10.01 10.01 20.16 9.32 9.91 9.83 19.81AFB cut efficiency 22.83% 22.47% 22.41% 22.02% 23.23% 23.02% 22.96% 22.03%tau->pinu cut eff. 5.34% 5.49% 5.56% 5.11% 5.36% 5.66% 5.74% 5.18%tau->rhonu cut eff. 6.21% 5.98% 5.48% 5.73% 5.87% 5.61% 4.95% 5.02%



-> -> Apol Apol

ProcessGeometry GLD GLD' J 4LDC LDC' GLD GLD' J 4LDC LDC'

Cross section (pb) 2.48 2.48 2.48 2.48 2.12 2.12 2.12 2.12Luminosity (fb-1) 9.785081 10.01371 10.0125 20.16129 9.315566 9.905189 9.826415 19.81132tau->pinu cut eff. 5.34% 5.49% 5.56% 5.11% 5.36% 5.66% 5.74% 5.18%

tau->pinu left 775 825 825 1580 460 500 509 922tau->pinu right 521 539 556 976 599 688 686 1254

Apol value 39.20% 41.94% 38.96% 47.26% -26.25% -31.65% -29.62% -30.51%Apol error 5.45% 5.29% 5.28% 3.84% 6.09% 5.73% 5.72% 4.24%

Apol error (500fb-1) 0.76% 0.75% 0.75% 0.77% 0.83% 0.81% 0.80% 0.84%


Need to check MC distribution w/wo cut


• Calculation of pol. value is complicated (not yet).

• Difference between eL/eR can be seen.• Difference between geometries can be seen,

need to check the reason.

-> -> , , ->-> Apol Apol


• Separation of cos(theta) ~ 0.6 is the best?

Theoretical angular distributionTheoretical angular distribution


• Combined information of tau to rhonu andrho to pipi decay can be used in this method.

Another methodAnother method

Physics Letters B, 235 (1990) 198


• AFB and Apol of tau-pair events are analyzed.

• Effective suppression of background can be achievable.

• AFB can be obtained with < 0.2% error in 500 fb-1

• Apol is obtained by both -> and ->, -> modes– Need more work for -> mode

• Difference of Apol between eL and eR can be seen

• Apol can be obtained with < 1% error in 500 fb-1

Tau-pair conclusionTau-pair conclusion

Full Simulation (Jupiter/MarlinReco) of Tau-pair/SUSY mode

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