Top Quark Mass Measurements at CDF Run II
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Transcript of Top Quark Mass Measurements at CDF Run II
CDF
Top Quark Mass Measurementsat CDF Run II
Top Quark Mass Measurementsat CDF Run II
Kohei YoritaUniversity of Chicago
For the CDF Collaboration
SLAC
June 7th 2005
bscdu
t
Brand New Results from CDF !Brand New Results from CDF !Run I World Average (hep-ex/0404010)
Mtop (world) = 178.0 GeV/c2+4.34.3
In the Lepton+Jets channel with 318 pb-1 data, (single meas.)
Current CDFOfficial Value !(Template Method)
Mtop (CDF) = 173.5 GeV/c2+4.14.0
Mtop (X-check) = 173.8 GeV/c2 (Very New !)+4.34.1
As a cross check, the same dataset and lepton+jets, but using Matrix Element MethodMatrix Element Method (DLM)
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 2/43
Run II
Better than Run I w
orld average
OutlineOutline
e bd
uμ
1. The Tevatron & CDF
2. Top Quark Physics3. Why Top Mass ?4. Top Quark Production and Decay
5. Key Points of the Measurements6. Top Quark Mass Measurements (L+jets) - Template Technique : (1D and 2D) - Dynamical Likelihood Method (DLM)
7. Summary
The World’s BestThe World’s BestMeasurementMeasurementThe World’s BestThe World’s BestMeasurementMeasurement
Dr. E. ParticleQ: How many particles in me?
The TeVatronThe TeVatron
The Tevatron is a proton-antiproton collider with 980 GeV/beam
RunI)(1.8TeV RunII in1.96TeV s
2 km
Record > 1.2 1032 !
The World’s only Top Factory !
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 4/43
Delivered luminosity : > 1fb-1 !!!(Run I : 110 pb-1)
Collider Detector at Fermilab (CDF)Collider Detector at Fermilab (CDF)
= 1.0= 1.0
= 2.8= 2.8
= 2.0= 2.0
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 5/43
> Tracking System
- New silicon tracker
b jet tagging !!!
- New central drift chamber
> New time of flight detector
> New Forward Calorimeter
- Jet (||<2.0) for top physics
> Extended muon coverage
> New Electronics, DAQ, Trigger ))2log(tan(
polar angle
Run II Upgrades
EEE /%14/ EEE /%80/
EM :
HAD :
Plug Calorimeter
Silicon Detector
COT
Some CDF PicturesSome CDF Pictures
Muon Chamber
Move In to Collision hall ! (Installation…)
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 6/43
Assembly hall at CDF
Sep. 2004shutdown
CDF Data TakingCDF Data Taking
90%
80%
CDF : Data taking efficiency is stably ~80-90% ! Now CDF has a total integratedluminosity of 800 pb-1 on tape!!!
Analyses for today’s talkbased on 318 pb-1
(Physics quality data until Sep. 2004)
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 7/43
Top Quark Production and DecayTop Quark Production and Decay
15% 85%
~100%
• Dilepton (e,μ) BR=5%
• Lepton (e, μ) +jets BR=30%
• All jets BR=44%
• + X BR=21%
• Dilepton (e,μ) BR=5%
• Lepton (e, μ) +jets BR=30%
• All jets BR=44%
• + X BR=21%
Final states : (depend on W decay)
* Higher statistics than dilepton * Lower background than All jets
Identify “leptonic W” by selecting (1) Isolated lepton (Et>20 GeV)(2) Missing Et > 20 GeV
Production Cross Section
qq , gg fractions reversed at LHC
Tree level Diagram
pb1.6)178( GeVmtpb7.6)175( GeVmt
pb7.5)180( GeVmt~30 % increase from Run I
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 8/43
Golden Channel
We have detected Top events!!! We have detected Top events!!!
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 9/43
Muon + Met + 4jets (2 bjets) candidate Counting Method (lepton+jets)
Control region Signal region
Top Quark PhysicsTop Quark Physics Interesting physics in the top sector
– Production Mechanism
– Direct contact with Vtb
– Decay into W+b before hadronization ( =410-25 s)
Unique opportunity to probe
bare quark properties.
(top spin(/correlation)? charge?)
Top quark mass at EWSB scale what does this tell us?
– Is top the gateway to new physics?
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 10/43
Decay modes
Branching ratios
CKM matrix
Rare decaysFCNC e.t.c.
Non-SM decays
Production X section
Resonance production
Production kinematics
Top Spin polarization
Top Quark MassW helicity (V-A?)
Why is Top Mass Interesting?Why is Top Mass Interesting?
MW ( Mtop2, ln(MH) )
(2) Special Relation to Higgs mass, together with W boson mass.
(1) Fundamental Standard Model parameter.
RunII Goal : M~ 2 GeV at CDF !
(4) By using the top mass as a constraint, ttbar full event reconstruction can be possible. This is very powerful for a test of SM (spin correlation, W helicity e.t.c), or search for non-SM physics ! (tt resonance e.t.c.)
12
v
my tt
(3) Top quark is heavy (~ 175 GeV = Mb-quark35) Yukawa coupling ~ 1. * Near the EWSB scale. * If we can measure strength of this coupling (i.e.ttH), a test of the Higgs sector in the SM can be possible.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 11/43
Top Mass Run I ReviewTop Mass Run I Review
New World Average (2004) Mt = 178.0 4.3 GeV (2.73.3) hep-ex/0404010
Old World Average (1999)
New DØ l+j measurement, (Nature 429, 638-642 (2004))
Standard Model Higgs Mass:
Most probable: 96 GeV 126 GeV Upper limit(95% CL):219 GeV 280 GeV
73 48
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 12/43
Mt = 174.3 5.1 GeV (3.24.0) (Fermilab-TM-2084)
Key Points of The AnalysisKey Points of The Analysis
How ? : SECVTX b-tagging (excellent silicon detector !)B hadrons are long-lived.
Identify by Vertex of displaced tracksfrom primary.
Backgrounds and Combinations (jet-parton assignments)
- b jet taggingb jet tagging is very important.
Tight Tagger 40% / jet 60% / tt eventMistag : ~ 0.5% / jet
Background Reduction - Background processes are mostly non-heavy flavor (W+jets, QCD) Reduce Combinatorics (Ambiguity to form top and anti-top) 2 b tag : 2 jet-parton permutations 1 b tag : 6 jet-parton permutations 0 b tag : 12 ways to assign 4jets to 4 partons
2 due to -pz ambiguity4/12/24 for 2/1/0 tag
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 13/43
Key : Jet Energy ScaleKey : Jet Energy Scale
All Jets are formed by dR=0.4 cone-clustering algorithm.
Calibrate forward calorimeter to central calorimeter. - uniform response in eta correction
Correction for non-linearity and energy loss in un-instrumental region.
Correction for leakages outside the cone.
Non-uniform response
Diff. resp.of /i+-Non-linearity
Shower, frag.
~ Precision on the determination of jet energies is necessary for Mt measurements ~
(1) “Relative to Central”
(2) “Absolute Scale” (to Hadron)
(3) “Out of Cone” (to Parton)
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 14/43
(4) Other : Very Small Corrections - Multiple Interaction (minbias, func. of Nvertex) - Underlying Event (minbias, nVtx = 0)
OOCUEAbsMIelrCalorimete
jetParton CCCCCPP R
Jet Energy UncertaintyJet Energy Uncertainty
Run II 2005
Run II 2004 Run I
Central region
Total fractional uncertainty on jet PtJet Energy Systematic Run II 2005 : O(~3%)Run II 2004 : O(~6%)Now, better than Run I !
- Better understanding of Calorimeter tuning.
> In the top quark mass measurements, there are lots of constraints available to improve precision. e.g. ) W Mass Constraint
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 15/43
Top Quark Mass Measurements~ Lepton+jets ~
1D Template Method2D Template Method
Dynamical Likelihood Method(Matrix Element)
Top Quark Mass Measurements~ Lepton+jets ~
1D Template Method2D Template Method
Dynamical Likelihood Method(Matrix Element)
1D Template Method1D Template Method
(2) Additional selection cut on resulting2(<9)
Top mass isfree parameter
(1) For each event, top mass is extracted by minimizing2 defined as,
(3) Build templates of Mt with smallest 2 from MC - Signal with different top mass - Each background source
(5) Fit to the data using unbinned likelihood.
(4) Parameterization : Build signal p.d.f. as a function of generated mass.
- Jets resolution term- Unclustered Energy term- W mass constraint and Top mass term
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 17/43
1D Template : Subdivision1D Template : Subdivision Use 4 categories of events
with different background content and reconstructed mass shape.
2-tag 1-tag(T) 1-tag(L) 0-tag
j1-j3 ET>15 ET>15 ET>15 ET>21
j4 ET>8 ET>15 15>ET>8 ET>21
S:B 18:1 4:1 1:1 1:1 Subdivision improves statistical uncertainty. Subdivision does not improve systematic uncertainty.
Expected Fraction of Sensitivity
2-tag 1-tag(T) 1-tag(L)
0-tag
35%
27
45%
32
9%
31
11%
37
0tag1tag,3.5j1tag,4j2tag LLLLL
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 18/43
Template RMS (GeV)
1D Template : Data Fit1D Template : Data FitCurves: expected signal andbackground from global best fit
Mtop (1D)= 173.2 (stat.) 3.4 (syst.) GeV/c2 +2.92.8
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16 ev 57 ev
25 ev 40 ev
1D Template : Systematics1D Template : Systematics
Jet Systematic Source Uncertainty(GeV/c2)
Relative to Central 0.6
Hadronic energy (Absolute Scale) 2.2
Parton energy (Out-of-Cone) 2.1
Total 3.1
Systematic Source Uncertainty(GeV/c2)
Jet Energy Scale 3.1
B-jet energy 0.6
Initial State Radiation 0.4
Final State Radiation 0.4
Parton distribution functions 0.4
Generators 0.3
Background Shape 1.0
MC statistics 0.4
B-tagging 0.2
Total 3.4
CDF Run II Preliminary (318 pb-1) This was ~ 6.2 GeV before (2004)
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 20/43
Our measurement is systematic dominant !> Statistical : <3.0 GeV> Jet Energy Scale : 3.1 GeV> Syst. Total : 3.4 GeV
Big Improvement since an year ago !
World’s Best Measurement !World’s Best Measurement !
Datasets and event selection are exactly the same as 1D template.
P1P1(mrecotop;mtop,JES) and P2P2(mreco
jj;mtop,JES)
2D Template Technique M top + JES Simultaneous Fit
using top mass and W mass templates
2D Template Technique M top + JES Simultaneous Fit
using top mass and W mass templates
Further Improvements of Jet Energy Scale(JES) Uncertainty
CDF’s improved Jet Energy Scale uncertainty almost half since an year ago.
1D Template : ~ 4.4 GeV total uncertainty1D Template : ~ 4.4 GeV total uncertainty
Run II 2005
Run II 2004 Run I
Central region
2D Template Why ? and What?
2D Template Why ? and What? Strong Motivation again.. :
- Current world average uncertainty (±4.3GeV/c2):
– 2.6 GeV/c2 from JES– 2.7 GeV/c2 from stat.
Jets are very hard to calibrate becausethere is no nice resonance.. Obviously, in the future, even now, this will give a limitation of precision!
Fractional error on jet Pt
Solution : Use W jj Mass !
1. Identify jets coming from W
2. Reconstruct their invariant mass mjj
3. mjj strongly dependent on JES
4. MW uncertainty is completely negligible (< 34 MeV)
5. mjj mostly independent of Mtop
JES from W jj is mostly statistical
mjj(W)
e
jetjet
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 22/43
Scale with Luminosity !!!!!
How to make Mjj template ?How to make Mjj template ? Which jets form W?• All Non-btagged jets pairs are take
n into account equally.• 1/3/6 mjj per event with 2/1/0 b-tag
Measuring JES• Make Mjj templates by varying JES 1 defined by CDF jet group • Fit data with Wjj to measure JES!
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 23/43
JES vs Mtop vs Mjj CorrelationsJES vs Mtop vs Mjj CorrelationsPDFs ( Mjj | Mtop, JES=0):2tag
Mjj
Mto
p
Mtop strongly depends on JESMjj independent of Mtop
So Mtop and JES are simultaneously determined in likelihood fit using shape comparisons of Mt and Mjj template to take into account these correlations.
JEStagtagLtagTtagtotal
JES
STD
LLLLLL
JESJESJES
0112
2
2
2
2
JES12
)0(
2
)(lnL-
A Gaussian constraint on JES
from the standard calibration is
included in likelihood as a priori
(01)
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How about b jets?How about b jets?
b Jet Systematic Source Uncertainty(GeV/c2)
HQ Fragmentation
(Peterson b=25-6010-4)
0.4
Semileptonic decay 0.4
B-jets colour flow 0.3
Total 0.6
Most b-jets energy scale
can be set using W→jj
Mtop measurement is sensitive to energy scale of b jets.
(W mass is constrained.)
- But studies show most uncertainty is shared by light quark and b jets.
- Only 0.6 GeV/c2 additional
uncertainty on Mtop due to
b-jet-specific systematics.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 25/43
Top Mass Result with 318 pb-1Top Mass Result with 318 pb-1
Mtop (2D)= 173.5 (stat) 2.5(JES) 1.7(syst.) GeV/c2
+2.72.6
c.f. 1D JES : 3.1 GeV
Black curvefrom globalbest fit.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 26/43
16 ev 57 ev
25 ev 40 ev
JES Results with 318 pb-1JES Results with 318 pb-1
Agreement data-MC JES is
quite good. Combined W jj and prior
JES yield 20% improvement
78.080.010.0
JES
Reconstructed dijet (W) mass:
Black curvefrom globalbest fit.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 27/43
Statistical uncertaintyStatistical uncertainty
We are a bit on the lucky side, but reasonable. (~9.2%) June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 28/43
Higgs Mass (SM global fit)using only 2D Template Results
Higgs Mass (SM global fit)using only 2D Template Results
Only based on this measurement, SM global fit returned,
25435 /94 cGeVM Higgs
(upper limit (95%CL) 208 GeV/c2)
C.f) Run I world average constraint:273
48 /126 cGeVM Higgs
Mtop (CDF) = 173.5 GeV/c2+4.1
4.0
150
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 29/43
Very preliminary Projection and Fit result.
The Future ProjectionsThe Future Projections Traditional calibrations of JE
S based on dijet and/or gamma-jet balance are expected to be limited in the future.
Using W jj : JES uncertainty scales with statistics.
So we can reach JES uncert. below 1 GeV/c2 in Run II
Reaching a total top mass uncertainty of 2 GeV/c2 can be possible in Run II
Now !
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 30/43
Other Technique?Other Technique?
Mtop = 173.0 (stat.) 3.3 (syst.)GeV/c22.92.8
> Another category : - 1D template (Secvtx + Jet Probability Algorithm for b tagging)
= 173.0 + 4.4 – 4.3 GeV All lepton+jets results are obtained from template technique. and consistent each other. (173.5(2D), 173.2(1D), 173.0(1D+JP))
What else ? Matrix Element Technique should be a good cross check and even can aim to have the best result. Dynamical Likelihood Method (DLM) !
Brief summary so far…… > Results from 1D and 2D template are presented.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 31/43
Dynamical Likelihood Method Introduction
Dynamical Likelihood Method Introduction
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 32/43
- Originally proposed in 1988 by K. Kondo.(J.Phys. Soc. 57, 4126)
The Method :- Basic idea is to use matrix elements convoluted likelihood.
The year Leon M. Lederman won the Nobel Prize !
For the neutrino beam methodand the demonstration of the
doublet structure of the leptonsthough the discovery of the
muon neutrino.
(1) Exactly 4 tight jets : Et > 15 GeV, |eta| < 2.0 do not use 4 more jets and loose 4th jet (Et > 8)(2) At least one SVX b-tagged jet do not use 0 b tag events. (to increase S/B.)
Event Selection : (Not the same as template !!!)
> DLM : 63 events> Template : 138 events
Likelihood Definition in DLMLikelihood Definition in DLM
xyx dwMPtfzzFFlux
MLt sI I
batopi ),(||)(),(
2)( 2
4
For i-th event, likelihood is defined as,
M : Matrix element of tt process,
F : Parton distribution function for (za,zb) and f : Pt of tt system
w : Transfer function, x ; partons y ; observables
)(2)( top
event
itop MLlnM
It : Jet-parton, Is : neutrino Pz (Sw=(l+)2)
222 ||)(|||| decrprod MsMM
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 33/43
All possible combinatory is taken into account.
Analysis procedure(1) At first, all events are considered as signal ttbar.(2) “Signal Likelihood” is calculated for each event.(3) Take joint likelihood of all events.(4) Bias correction by using “mapping function”. Mapping function : function of bkg fraction.
- 12/4 sum for 1/2 b tag in total.
DLM : Demonstration!DLM : Demonstration!
L
Mtop (GeV)165 185 10 events likelihood distributions: L(M)
For ppt user!
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 34/43
Using SM-Matrix Element is too much assumption ?
Using SM-Matrix Element is too much assumption ?
(1) CDF has probed the properties of top quark but - NO significant discrepancy has been observed. (Discovery mode Detailed study)(2) In the Standard Model, no fundamental/direct prediction of Mt.(3) Too much rely on SM ? - All Monte Carlo Events are generated based on SM.
(4) Only considering Leading-Order ME. How about NLO? - At first order, selecting events with exactly 4 jets minimizes it. Need careful study (related to ISR/FSR, PDF uncertainty)
(5) BIG ADVANTAGE : Using maximal event information. The most effective term is “propagator” (not too much assumption here!!!)
< Apparently, it is worth pursuing !!!>
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 35/43
How likelihood dist. looks like?How likelihood dist. looks like?
Signal example: - log(likelihood)
Blue : all added upRed : right comb.Black : wrong comb.
Blue : all added upBlack : each comb.
Peak around 175 GeVLikelihood tends to be higher inlower mass region.
Range[155-195]GeV
Bkg example: - log(likelihood)
25 events example for sig and bkg using generator level input
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 36/43
Background Effect/CorrectionBackground Effect/Correction
Source W+4jets (318pb-1)
Mistag 5.97 ± 0.80
Wbb 1.87 ± 0.83
Wcc 0.99 ± 0.46
Wc 0.60 ± 0.25
Single top 0.41 ± 0.09
Diboson 0.39 ± 0.08
QCD 2.85 ± 1.33
Bkg Total 13.07 ± 2.19
Data 63 (e:39, mu:24)
Each Background Effect ~ 2 GeV shift at 21 %.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 37/43
Mapping Function Slope changes stably.
slope
Bkg : 21%
* From 1000 pseudo expt. for each point
Linearly / Pull checkLinearly / Pull check
1.05 biasSlope of 1
No bias for central value. 5% correction for the statistical uncertainty. - Assumption is only held for tt events. (4p-4j matched.)
- Not held if ISR/FSR gluon enters leading 4jets. - Not held for dilepton or backgrounds…..
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 38/43
DLM Results (318 pb-1)DLM Results (318 pb-1)Correction at background fraction of 21%.
Mtop (DLM)= 173.8 (stat.) 3.3 (syst.) GeV/c2 +2.72.5
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 39/43
DLM Stat. and SystematicsDLM Stat. and Systematics
Sources Mtop(GeV/c2)
Jet Energy 3.0
Transfer Function 0.2
ISR 0.4
FSR 0.5
PDF 0.5
Generator 0.3
bkg fraction (6.7%) 0.6
bkg Modeling 0.6
b tagging 0.2
b jet energy 0.6
TotalTotal 3.3 3.3
Data/MC comparison ofData/MC comparison ofStatistical uncertaintyStatistical uncertainty
Systematic uncertaintySystematic uncertainty
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 40/43
10% prob.MC < Data
Data/MC ComparisonsData/MC Comparisons
195
155)( dMMLL ii
ev
For i-th event,
Event likelihood Event-by-event Maximum Likelihood Mass
Note : Last bin includes over flow.
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 41/43
Improvement for JES uncertainty ?~ Hadronic W(jj) Mass ~
Improvement for JES uncertainty ?~ Hadronic W(jj) Mass ~
Remove W Mass constraintfrom likelihood. Instead, topMass is constrained.Then pick up 2 jets W massAt maximum likelihood point.
(1) We have a confidence to use W Mass as a constraint !
(2) In principle, DLM can use this to reduce jet energy uncertainty like 2D Template!!! - Future improvement here!!!
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 42/43
SummarySummary> Tevatron is performing very well. Delivered luminosity more than1 fb-1
CDF recorded >800 pb-1 data
> 2D template (Mt+JES) provided the best measurements in the world.
-- Lots of work to reduce systematics, - especially JES!!!
> New techniques are developed. DLM and template results are consistent.> Other technique/channel (dilepton/all jets) are coming very soon!
> Plan to publish these two results by the endof this summer.(PRDs)
> Combination on going..
Will reach goal of measuring mt to ~ 2 GeV in Run II ! Getting Close !!!
June 7th , 2005 Kohei Yorita , U of Chicago , SLAC Seminar 43/43
BackupBackup
JES : Relative CorrectionJES : Relative CorrectionThe Central Calorimeters( = 0.2-0.6) are better calibrated/understood.Correction factor is a function of Pt and extracted from dijet balance. (check -jet balance)
Uncertainty : ~ 1% level(depends on region and Pt)- estimated by varying the selection requiremens and fitting procedure.
JES : Absolute Scale Correction(to hadron level)
JES : Absolute Scale Correction(to hadron level)
Uncertainty : 2 ~ 3% level (strong dependency on Pt)- Single particle E/P, fragmentation. - Smaller error : MC/data in tower boundaries, cal. calibration with time.
Correction for non-linearly and un-instrumental region, based on MC by using single particles (pion,protons,neutrons ). We tuned MC much better and map to hadron level from cal. level.
JES : Out of Cone Correction(to parton level)
JES : Out of Cone Correction(to parton level)
Correction for energy leakage outside the cone.(0.4 for top physics)0.4 is small compared to typical QCD events since tt events are crowded butLose >10% energy for jets with Et<20 GeV.
Uncertainty : 2 ~ 8% level (strongly depends on Pt)- Difference between data and MC is taken into account. (We can compare energy sum outside the cone of jets.)
Results on Blind SampleResults on Blind Sample
* Some are Pythia, Others are Herwig. (P - H Syst. = - 0.3 GeV)
We observed “NO BIAS”.
5 blinds samples generatedby CDF Top Mass group
0.3 GeV is stat. only.
All is w/I 1 standard deviation.
DLM measurements of nonSM model (tt resonance X(700))
DLM measurements of nonSM model (tt resonance X(700))
Sample : X(700) to tt (M=175 GeV), top decay follows SM
Reconstructed mass from 30 events P.E. is 176.8 0.4GeV. If X(700) is 100% in the sample, we see 2 GeV bias.
Additional Checks on DLMAdditional Checks on DLM
-4.1 GeV
16 events overlap between this round and before (162 pb-1)
Transfer function w(x,y)Transfer function w(x,y)
definition Sample Other
T.F. All Mass
130-230, 5 GeV step averaged
1/Nx weight
Comment Slicing “Et” of jets into 10bins and eta into 3 bins
To minimize top mass dependence of TF.. 130-230 is wide enough for search range.
Avoid double counting
)(
)()(
PartonE
JetEPartonE
T
TT
Parton Energy is inferred by random generation along the T.F.
Et dep.Eta dep.
Details on Systematic UncertaintyDetails on Systematic Uncertainty
Systematic TMT 2-D TMT 1-D
Mtop (GeV)Mtop (GeV) JES()
JES (2.5 ) - 3.1
b-jet modeling 0.6 0.25 0.6
ISR 0.4 0.08 0.4
FSR 0.6 0.06 0.4
PDFs 0.3 0.04 0.4
Generators 0.2 0.15 0.3
Bkgd shape 1.1 0.17 1.0
b-tagging 0.1 0.01 0.2
MC statistics 0.3 0.04 0.4
Method 0.5 0.02 -
TOTAL 1.7 0.36 3.4 = 3.1 1.4
Details on Systematics : ISR/FSRDetails on Systematics : ISR/FSR In Run I, switch ISR on/off
using PYTHIA, dM top = 1.3GeV In Run II: systematic approach
ISR/FSR effects are governed by DGALP evolution eq.:<Pt> of the DY(ll) as a function of Q2
(2Mt)2
log(M2)
ISR syst: 0.4 GeV
Pt(tt) at generator
μ+
μ-
Details on Systematics : b jetDetails on Systematics : b jet