1. Martin zur Nedden, HU Berlin 1 b-tagging / Single-Top Meeting, March 2010 b-tagging Performance Studies: Status Report from Berlin Regular single top meeging March 16 th 2010 Carsten Kendziorra, Martin zur Nedden Humboldt-Universität zu Berlin

2. Martin zur Nedden, HU Berlin 2 b-tagging / Single-Top Meeting, March 2010 B-tagging perfomance ● studies done with Athena release 15.6 ● MC 08, 10 TeV data samples ● MC generators used / samples: – Pythia for single top t-channel – MC@NLO for ttbar – Alpgen for W+jets ● basic analysis object selection (electron, muon, jets) ● no specific cuts for single top or t-tbar ● no trigger selection

3. Martin zur Nedden, HU Berlin 3 b-tagging / Single-Top Meeting, March 2010 Performance Studies ● all jet algorithms: (cone, antiKt, AtlFast) – AntiK14H1Tower and Con4H1Tower ● all taggers: (JetProb, TrackCount, BaseLine, IP1/2/3D, SV0/1/2) – TrackCounting and BaseLine (SV1 && IP3D) ● making basic selection cuts – medium electrons, isolated: author = 1 or 3, etcone20 20 GeV, |η| 1.52) – combined stacco muons, isolated etcone20 20 GeV, |η| < 2.5 – jets, overlap removal under construction p T > 30 GeV, |η| < 5.0

4. Martin zur Nedden, HU Berlin 4 b-tagging / Single-Top Meeting, March 2010 Structure of the b-tagging performance Tool

5. Martin zur Nedden, HU Berlin 5 b-tagging / Single-Top Meeting, March 2010 Weights (single top t-channel sample) Track counting Tagger BaseLine Tagger μν eνeν

6. Martin zur Nedden, HU Berlin 6 b-tagging / Single-Top Meeting, March 2010 Correlations of Efficiency and Weight Track counting Tagger BaseLine Tagger

7. Martin zur Nedden, HU Berlin 7 b-tagging / Single-Top Meeting, March 2010 Purities Track counting Tagger BaseLine Tagger

8. Martin zur Nedden, HU Berlin 8 b-tagging / Single-Top Meeting, March 2010 Rejection Factors Track counting TaggerBaseLine Tagger

9. Martin zur Nedden, HU Berlin 9 b-tagging / Single-Top Meeting, March 2010 Results for Track Counting Tagger sample weight cut cone4/ antiKt Efficiency cone4/ antiKt rej. Factor cone4/ antiKt purity cone4/ antiKt single top 4.65 3.95 3.25 2.15 /2.05 0.4 0.45 0.5 0.6 84 / 94 67 / 69 44 / 47 22 0.99 0.98 0.97 / 0.96 4.75 3.95 3.25 2.15 / 2.25 0.4 0.45 0.5 0.6 55 / 56 43 33 19 / 20 0.95 0.94 0.91 W + jets 2.15 / 2.55 2.05 / 2.15 1.45 / 2.05 1.05 / 1.45 0.4 0.45 0.5 0.6 22 / 28 20 / 23 12 / 22 7 /12 0.033 / 0.036 0.033 / 0.035 0.021 / 0.035 0.015 / 0.023

10. Martin zur Nedden, HU Berlin 10 b-tagging / Single-Top Meeting, March 2010 Results for Track Baseline Tagger sample weight cut cone4/ antiKt Efficiency cone4/ antiKt rej. Factor cone4/ antiKt purity cone4/ antiKt single top 8.85 7.65 6.55 / 6.45 4.25 0.4 0.45 0.5 0.6 2202 / 3526 1101 / 1175 1101 / 705 206 / 220 0.98 0.97 0.96 9.15 / 9.25 8.15 6.95 / 7.15 4.65 0.4 0.45 0.5 0.6 188 132 / 131 98 / 104 54 / 56 0.99 W + jets 3.65 / 4.35 2.95 / 3.25 1.85 / 2.35 0.25 / - 0.05 0.4 0.45 0.5 0.6 118 / 146 88 / 106 57 / 77 16 /12 0.081 / 0.093 0.072 / 0.075 0.050 / 0.063 0.017 / 0.012

11. Martin zur Nedden, HU Berlin 11 b-tagging / Single-Top Meeting, March 2010 Summary and Outlook ● implement overlap removal ● include trigger selection ● look also at JetProb and SV0 taggers ● redo the study wiht 7 TeV MC ● look with the tool into first data, compare weights of data and MC ● strategies for efficiency determination with data – tag and probe method? ● study impact parameters and secondary vertices with first data – understand the taggers – develop a b-tag veto ● Overview talk by Carsten at the next informal b-tag meeting at 7 th of April