ttbar τ + jets : update on qcd estimation
DESCRIPTION
ttbar τ + jets : Update on QCD Estimation. William Edson SUNY at Albany. PDF Unc. The PDF uncertainty of an observable can be evaluated basically in three ways: - PowerPoint PPT PresentationTRANSCRIPT
ttbar τ + jets:Update on QCD Estimation
William EdsonSUNY at Albany
PDF Unc.
The PDF uncertainty of an observable can be evaluated basically in three ways: • Intra-PDF uncertainty: this is the uncertainty within a given
PDF set. E.g. the PDF that is used for the generation of a sample has an uncertainty and this uncertainty propagates to the uncertainty of the observable. Usually a certain PDF is accompanied by a set of error PDFs (PDF error set) and there is a PDF-dependent prescription how to evaluate the PDF uncertainty using these error PDFs.
• Inter-PDF uncertainty: this is the variation when switching from one PDF (set) to another PDF. The comparison is made using the best fit PDF (or central value) for each PDF and compare the variation of the observable
• Full-PDF uncertainty: this is the combination of the inter and intra-PDF uncertainty. A procedure has been agreed on by the PDF4LHC working group how to combine the both uncertainties. This is the so-called envelope of the variations and uncertainties
Cross Section Results
CT10 MSTW NNPDF
Fit Results:Mean: 1.77000e+02Sigma: 6.43115e-01
Fit Results:Mean: 1.77462e+02Sigma: 4.31322e-01
Fit Results:Mean: 1.77317e+02Sigma: 1.20957e+00
Intra-PDF Uncertainty
CT10: Symmetric Hessian, in addition reduce the uncertainty by 1.645
to correspond to 68 % C.L. errors delta X = 0.5 * sqrt( sum ( (X_i+ - X_i-)^2 ) )
MSTW: Asymmetric Hessian, check pairwise, if the uncertainty is a
variation up or variation down and add them correspondingly to the error up or error down, but if X_2i and X_2i-1 are both in one direction, just use the larges errorup=sqrt( sum_i (max(0,X_2i-X_0,X_2i-1-X_0)^2 ), check for
i=1..N/2 errordown=sqrt( sum_i (max(0,X_0-X_2i,X_0-X_2i-1)^2 ), check for
i=1..N/2 NNPDF:
The best value is the mean of all the ensembles and the uncertainty is the standard deviation
Intra-PDF Uncertainty Results
CT10: ± 2.49152
MSTW: + 1.40766 / - 1.48663
NNPDF: ± 1.27205
Inter-PDF Unc and Envelope All uncertainties are combined in a linear way, this is
the extremum (min and max) of all variations is taken and the half of the interval is the uncertainty. This is also called the envelope. Please see the attached plot as an example of what is meant by the envelope.
Envelope Results
Therefore the final uncertainty is equivalent to the CT10 Intra Unc: ± 2.49152
Fit Selection Results
New Results for Fit: Signal Fraction:
0.691497±0.0411817 Chi2: 28.25 Meas. Used: 31 σ: 166.798±9.93353
New Corrected Results: Signal Fraction:
0.691158 ± 0.0411817 σ: 166.716 ± 9.93353 Correction Systematic:
± 9.83197
Sample Fraction Cor. Fraction
σ Var (absolute)
Variation (%)
Nominal0.691497 0.69115844 166.7161572
- -
JER0.672992 0.673559772 162.9258293 3.790327965 2.273521672
JRE0.689147 0.688923538 166.7658078 0.049650592 0.029781512
JES up0.663975 0.664984403 148.3058473 -18.41031 -11.04290686
JES down0.710838 0.709552164 186.1850579 19.46890068 11.67787274
JVF up0.691927 0.69156738 165.9798167 -0.73634055 -0.441673175
JVF down0.691266 0.690938754 167.4725207 0.756363447 0.45368335
BSF up0.692051 0.691685307 162.7936077 -3.9225495 -2.352831041
BSF down0.691526 0.69118602 170.9894612 4.273303955 2.563221242
MET up0.677634 0.677974417 161.4067264 -5.30943081 -3.184712807
MET down0.697884 0.69723262 171.3349064 4.618749209 2.770426866
Tau trig up0.715279 0.713775654 170.9325433 4.21638605 2.529080636
Tau trig down 0.660496 0.661675796 161.3423583 -5.37379896 -3.223322231
TES up0.696876 0.69627399 168.4991793 1.783022132 1.0694957
TES down0.676512 0.67690737 168.4803242 1.764167034 1.058185999
Tau Eveto SF up 0.69179 0.69143709 166.7586732 0.042515957 0.025502002
Tau Eveto SF down 0.691205 0.690880742 166.6736624 -0.04249481 -0.025489318
Sample Fraction Cor. Fraction
σ Variation (absolute)
Variation (%)
Nominal0.691497 0.69115844 166.7161572 - -
Wnorm Up0.680859 0.681041465 156.0894795 -10.6266777 -6.374113875
Wnorm Down 0.702949 0.702049548 177.7818978 11.06574061 6.637473413QCD
Bin/Range Up 0.712367 0.711006277 171.5037064 4.787549171 2.871676777
QCD Bin/Range
Down 0.652323 0.653903091 157.7296957 -8.98646149 -5.390276285HiISR
0.66 0.661204089 120.5933169 LowISR
0.66682 0.667690062 105.806385 7.393465966 4.434762707QCD Temp
0.700997 0.700193153 168.8954441
0.680189 0.68040428 164.1221176 4.773326 2.863146MC Gen
0.704682 0.70369767 141.7262448 13.69472173 8.214393829Lumi Top Systematic Uncertainties twiki
https://twiki.cern.ch/twiki/bin/view/AtlasProtected/TopSystematicUncertainties2011#Luminosity 1.8
Trigger Eff. Search for charged Higgs bosons in the τ+jets final state in t¯t decays with4.6 fb−1 of pp collision data recorded at √s = 7 TeV with the ATLAS
experiment— Supporting Note ATL-PHYS-INT-2012-047+ 2.9
- 4.8TauID Study of hadronic tau identification 1 using W and Z events ATL-COM-
PHYS-2012-1744-1 2.4
Fit Selection Results
Final Result: σ: 166.716 ± 5.897% (stat.) ± [to be calculated] (syst.)
Back-up
QCD Bin/RangeSample Fraction Cor.
Fractionσ Variation Variation
(%)
Nominal 0.691497 0.69115844 166.7161572 - -
Range+1 0.685245 0.685212649 165.2819571 -1.43420016 -0.860264648
Range+2 0.684087 0.684111365 165.0163135 -1.69984376 -1.019603494
Range+3 0.680152 0.680369092 164.1136299 -2.60252733 -1.561052853
Range-1 0.708654 0.707475131 170.6519493 3.9357921 2.360774244
Range-2 0.674656 0.675142273 162.8528551 -3.86330214 -2.317293177
Range-3 0.686839 0.686728578 165.6476184 -1.06853877 -0.640932939
Bins+1 0.712367 0.711006277 171.5037064 4.787549171 2.871676777
Bins+2 0.66001 0.6612136 159.4930829 -7.2230743 -4.332558059
Bins-1 0.652323 0.653903091 157.7296957 -8.98646149 -5.390276285
Bins-2 0.680357 0.680564051 164.1606566 -2.55550061 -1.532845199
Range increases/decreases in steps of 20GeVBin amount increases/decreases in steps of 5
MC Generator
Sample Fraction Cor. Fraction
σ Variation (absolute)
Variation (%)
Nominal0.691497 0.69115844 166.7161572 - -
AlpHerwig (baseline) 0.704682 0.70369767 141.7262448 13.69472173 8.214393829MC@NLO (105200) 0.691497 0.69115844 166.7161572 11.29519073 6.775102618
SYST_AtF_105860 0.721128 0.719338184 147.5099697 4.809637762 2.884925998
SYST_AtF_117050 0.663466 0.664500333 142.700332 - -
SYST_Full_117050 0.696679 0.696086638 155.4209665 - -
1.1) fullsim mc11c POWHEG+fPythia sample 117050 (SYST_Full_117050) and MC@NLO+fHerwig sample 105200 (MC@NLO(105200)) 1.2) fullsim mc11c POWHEG+fPythia sample 117050 (SYST_Full_117050) and the fullsim mc11c ALPGEN+HERWIG samples (AlpHerwig(baseline)) 1.3) AtlFast2 mc11b POWHEG+fPythia sample 117050 (SYST_AtF_117050) POWHEG+fHerwig sample 105860 (SYST_AtF_105860)
Mean Values of Ensemble Fits
Input Fraction
Previous Gaussian
Mean Output Fraction
Unc. Gaussian Mean
Output Fraction
Unc.
0.1 -0.0998291 0.00487524 -0.0446980 0.00328233
0.2 0.0501427 0.00241776 0.0951311 0.00259107
0.3 0.204145 0.00187353 0.238714 0.00232490
0.4 0.335251 0.00170598 0.375513 0.00173264
0.5 0.460622 0.00147548 0.493003 0.00146445
0.6 0.580640 0.00134429 0.604560 0.00130854
0.7 0.689419 0.00114811 0.710087 0.00111043
0.8 0.794341 0.00116489 0.805370 0.00103862
0.9 0.894616 0.00111430 0.903587 0.000966135
Linearity Test to All Values
Y(0): -0.127757 ± 0.00142161 Slope: 1.18358 ± 0.00252649 Chi2: 34.4482 NDF: 8997
Adjust Range for Linear Fit?
Range Y(0) Slope Corrected σ
0.1 – 0.9 -0.127757
1.18358 166.9633031
0.2 – 0.9 -0.100011
1.14196 167.1877651
0.3 – 0.9 -0.066934
2
1.0947 167.1171989
0.4 – 0.9 -0.035256
1
1.0515 166.7161572
Top Mass
Sample Fraction Cor. Fraction
σ Variation (absolute)
Variation (%)
Nominal0.691497 0.69115844 166.7161572 - -
SYST_Full_117050 0.696679 0.696086638 155.4209665 - - 167.5
0.680298 0.680507941 174.4111694 18.99020294 11.39073936170.0
0.689551 0.689307751 163.0755472 7.654580765 4.591385078175.0
0.694819 0.694317737 147.5410892 -7.87987725 -4.726522839177.5
0.673263 0.673817499 136.8370372 -18.5839292 -11.14704751
𝑠𝑓=(𝜎 (𝑛𝑜𝑚𝑟𝑒𝑓 . ) {=177.31 }𝜎 (𝑟𝑒𝑓 )𝑖 )∗𝑘𝑓𝑎𝑐 𝑖∗𝜎 (𝐹𝐸 )𝑖∗( 𝐿𝑢𝑚𝑖
𝑁 𝑖𝑛𝑖𝑡𝑖𝑎𝑙)
MC Tau PlotsMC Tau Count MC Tau Children
pdgIDMC Tau Children Count
Leptonic pdgID values: e → 11, μ → 13, τ → 15
MT Signal vs Control vs MC Backgrounds
Samples Normalized to Own Integrals
Samples Normalized to Sum of Integrals
Fits/Hists for Ensemble Tests
Cutflow C0: GRL C1: Trigger C2: Primary vertex with ntracks > 4 C3: Electron/muon overlap C4: Jet cleaning C5: Lepton Veto C6: tau n ≥ 1 C7: njets >= 4 with eta < 2.5 and |jvf| > 0.75 C8: MET > 60GeV C9: MT < 80GeV C10: >= 1 bjet
C11: Trigger matched tau n ≥ 1 and pT >= 40GeV C12: MC tau object match
Chi-squared minimization
Equation:
N(x): total number of events of type x for distribution n(x)i: number of events in bin of type x frac(Sig): fraction of N(Remain) expected to be Signal binfrac(x)i: fraction of events in bin of type x expected
from MC or template σi: uncertainty in bin i
2
i
iiii2
σ
)n(OB)D)binfrac(QC*N(Remain)*frac(QCD)g)binfrac(si*N(Remain)*(frac(Sig)n(Data)χ
N(OB) - N(Data) N(Remain)
frac(Sig) - 1 frac(QCD)
Chi-squared minimization cont.
σi determined using factors for: bin error:
data signal, MC QCD template other backgrounds, MC
statistical error: data: signal region other backgrounds, MC signal, MC QCD template (uncertainty of background region
data and all MC background region carried through via default SumW2
Highest pT bjet reconstruction
Results for plot: chi-square: 9.818 p-value: 0.7753 ndf: 14 chi/ndf: 0.7012
2nd Highest pT bjet reconstruction
Results for plot: chi-square: 13.66 p-value: 0.5517 ndf: 15 chi/ndf: 0.9107
Dijet Mass reconstruction
Results for plot: chi-square: 15.47 p-value: 0.6297 ndf: 18 chi/ndf: 0.8594
MET
Results for plot: chi-square: 15.87 p-value: 0.1971 ndf: 12 chi/ndf: 1.323
Closest pT bjet reconstruction
Results for plot: chi-square: 14.39 p-value: 0.2123 ndf: 11 chi/ndf: 1.308
New Event Selection Verification (Only uses MC so Excludes QCD)
Cut Sig Evts
Fakes Sig Eff. Fake Ratio
Rej Fact.
Sig/sqrt(Bkg
d)
Sig/Sqrt(Sig
+Bkgd)
C5Lep Veto
5863 1451086
- - - 4.867 4.857
C6ntaus >
0
5863 138276 1 0.09529 0.04240 15.77 15.44
C7njets
3191 11025 0.5443 0.07973 0.5318 30.39 26.76
C8MET
2583 7598 0.8095 0.6892 0.41998 29.63 25.60
C9MT
1892 3968 0.7325 0.5222 0.6510 30.04 24.72
C10bjet
1650 1230 0.8721 0.30998 1.538 47.05 30.75
C12Trig
match
941 335 0.5703 0.2724 4.925 51.41 26.34