Motivation Fact: The multi-generational structure of the quark doublets requires explanation and could herald compositeness. CDF: PRL 82 (1999) 2038 Under hypothesis of compositeness, deviation from point-like behavior would likely manifest in third generation. Conclusion: g bb may exhibit desired deviant behavior. Explore b quark dijet mass as a possible signature. Problem ~100:1 QCD:bb Solutions tagging 2nd VTX tagging Fit to CDF
qQCD calculation Impact parameter -tagged Jet Cross-section Jet + (Pt > 5 GeV) N ( f b b f B B ) T PV j L pt Given the simplicity of the calculation, there are few likely sources of the excess seen in p13. These could conceivably be N JES (central value) Resolution (i.e. smearing) T Trigger Eff PV Primary Vertex Eff j Jet Eff Correlated Eff
fb Frac b (Pt > 4 GeV) fB Frac B (Pt > 4 GeV) L Luminosity pt Pt bin width b b cross-section B BKD cross-section p13 p14 Analysis Summary Inclusive -tagged jet corrJCCB (0.5 cone jets) Standard Jet quality cuts, Standard JET Triggers Jet tagged with MEDIUM muon (more on this later) R(, jet) < 0.5 |yjet| < 0.5 JES 5.3 Long term goal was b-jet xsec. Difficult due to no data-driven determination of b-fraction. p14 Skimming
Start with CSG QCD skim Turn into TMBTrees (40M eventson disk) Skim on Trees Remove bad runs (CAL, MET, SMT, CFT, JET, Muon) Remove events w/o 2 jets Use Ariel d0root_ based package SKIM 1: 1 leading jet has ~ MEDIUM (P() > 4 GeV) SKIM 2: 1 leading jet has ~ loose SVT p14 All Data: CSG Skims Analyzed 1 2vtx 1 mu Luminosity JT 25 JT 45 JT 65 JT 95 JT 125 Pre Nov 03 Post Nov 03 40,460,043 16,301,242 24,158,801
1,538,291 646,047 892,244 405,671 171,107 234,564 1.76 28.31 141.05 288.61 289.61 Bad Run Removed 1.02 0.74 21.03 7.28 85.70 55.35 143.14 145.47 143.14 146.47
Bad runs & lumblk removed in luminosity. Only bad run removed in event counts for skims. Up until Run 193780 (07-JUN), V12.37. Trigger Turn On F Eff TurnOn Pt Jet Trigger Slope 1 e Collinear muon |yjet| < 0.5 Luminosity weighted Statistics uncorrelated poisson (wrong, of course) JES corrected (5.3) Distribution of MEDIUM tagged jets
(+ mycuts) (jet+) These cuts clearly improve the fake rate. Some residual fake s must persist. How s must persist. How many? CHF should be higher for punch through jets? Closer Look Suspicious JT45_TT Pt() 4.5-5.0 4.0-4.5 Pt() What is now a muon?
Medium muon (as defined by ID group) At least one scintillator hit in BC. Pt(central track) > 5 GeV |Pt(central) Pt(global)| < 15 GeV Rejected if A layer 4.25 < (muon) < 5.15 AND |(detector)| < 1.1 cal Fake from punch-through In a jet environment is an issue jet Efficiency/Fraction Summary N T PV j ( f b b f B B )L pt Detail
Efficiency T Trigger Eff PV Primary Vertex Eff Eff j Jet Eff fB Frac B (Pt > 4 GeV) fb
Frac b (Pt > 4 GeV) [0.37 0.05] Value 1.000 0.84 0.005 0.41 0.05 0.99 0.01 Pt dependent Pt dependent JES Definitions Required identically 2 jets Pt(jet 3, uncor) < 8 OR third jet doesns must persist. How t pass jet QC One jet contains muon, the other doesns must persist. How t. | | > 2.84 Imbalance variable: Pt ( w/ ) Pt ( w/o ) I 2 Pt ( w/ ) Pt ( w/o )
Independent variable: Pt ( w/ ) Pt ( w/o ) I 2 2 Pt ( w/ ) Pt ( w/o ) Pt ( w/ ) Pt ( w/o ) JES v5.3 STD JES 5.3 gives a 3.8% offset for -tagged jets. Pt ( w/ ) Pt ( w/o ) 2 2 Pt ( w/ ) Pt ( w/o ) Pt ( w/ ) Pt ( w/o ) It is independent of Pt (75-250 GeV). Maybe
higher above that. Need to rebin and revisit the idea that the muon Pt may be mismeasured. Same plot when scaling the -tagged jets by 3.8%. Pt ( w/ ) Pt ( w/o ) 2 JES v5.3 Energy Resolution (Fixed) 2 2 2 N S C2 Pt Pt Pt
2 10.8 0.90 dof 15 3 Fitting Functions x2 ,i 2 18 ( yi x1,i 2 17.33 1.15 dof 18 3
s /2 0 N pt e x2 ,i 2 18 Value Error N 9.56 107
1.7 106 3.195 0.004 5.61 0.04 ( pt ptm ) 2 2 2 dpt dptm )2 yi2 i 0
( yi pt 1 e 2 x2,i x1,i Variable x1,i 0 s /2 2 e
Nj pt kj j 1 1 e 2 x2,i x1,i ( pt ptm ) 2 2 2 dpt dptm yi2 i 0
2 17.96 1.28 dof 18 4 )2 Variable Value Error N1 7.62 0.32 k1 16.90
1.26 N2 3.28 0.60 Extraction of Correction Factors 2 17.96 1.28 dof 18 4 normal 2 17.33 1.15 dof 18 3 exponential
Point by Point Unsmearing Factors normal Unsmeared R Smeared Exponential Unsmearing Error 15.0 % Deviance 10.0 5.0 0.0 -5.0 0 100
200 300 -10.0 -15.0 Jet Pt (GeV) 400 500 Unsmearing Error small ~5% for Pt > 100 GeV PtRel at High Pt PtRel muon jet Fitting to HF fraction
Systematic Error Breakdown MC Comparison Pythia using standard D MC. NLO uses NLO++ (CTEQ6L) From Pythia, find fraction of jets tagged with muons (HF only). Multiply NLO cross-section by Pythia muonfraction. This is effectively the NLO k factor. Status DNote and Conference note to EB025 Residual small bug in code (should have only a few percent effect). JES error must be reduced to use this before setting limits on new physics.
