Btag POG Planning for the October exercise

1. Btag POGPlanning for the October exercise T. Boccali, W.Adam 23/9/09

2. Objective • We want to fake/simulate the first calibration activities, which can take place when ~ 10 pb-1 of _reasonable_ data are collected(as done in late 2007 but with more time/usage constraints) • Generally, two distinct type of analyses • Get a sample depleted in b, measure mistag • Get a sample enriched in b, measure efficiency • We want to test the method to share this info with the analysis users (absolute first). • The results distributed to the users will contain realistic values for efficiency and mistag together with the best estimate of the uncertainties we can obtain in the 2 weeks period of the exercise. • The main objective is to provide the necessary environment for PAGs to prepare for the use of b-tag calibration in their analyses. BTag POG - October exercise

3. Efficiency measurements: pTrel • Allows the measurement of the b fraction • in samples enriched in b jets via prompt muon selection • before and after the application of a nearly independent b tagger • Uses MC to extract ptrel templates • for b and non-b (2 templates) • sufficient at Tevatron energies • or b, c, light (3 templates) • Determine fractions by fit to data BTag POG - October exercise

4. Efficiency measurements: pTrel • Two approaches • measurement of the absolute efficiency in data • in a (limited) number of bins in ET and η • will start with 1D dependencies; need to check factorization • measurement of the relative efficiency data/MC • relies on the description of the relative variations by MC • remaining uncertainties absorbed in systematics • we need to keep both options • the quality of the data / MC comparison on first data will decideon the path to take BTag POG - October exercise

5. Efficiency measurements: System8 • Measures b- and light-quark content using a system of equations • using two taggers and two sub-samples with different b-content • minimal dependence on MC (only correlations) • absolute measurement • binning in ET and η as described before BTag POG - October exercise

6. Mistag rates: negative tags • In the past mostly used mostly for IP based taggers: • uses negative IPs to estimate the light-quark contaminationfor positve IPs • In CMS: concept extended to all taggers • Negative tag efficiencies are measured • Results are extrapolated to positive tags via a correction from MC, “R” BTag POG - October exercise

7. Technically Before the start CRAB (estimate ~< few days if all fine with GRID) Analyses macros: few minutes technical time (+ whatever human time needed for understanding 1-2 hours of emacs work to prepare configs AFTER the exercise (not part of it) BTag POG - October exercise

8. Data sets and skimming • Data needed for the calibration • (unbiased) QCD samples for the negative tags • MC: QCD_Pt* samples • QCD with muons associated to jets for the efficiency measurements • MC: InclusiveMu5_Pt* samples • Triggers (based on 8E29 even if 1E31 is more relevant for b-tag …) • HLT_Jet50U • PD_Jets, SD_Jet50U • HLT_Mu5 (use of low-threshold muon trigger planned for8E29)HLT_ BTagMu_Jet10U (test of b-tag calibration trigger) • PD_Mu, PD_Mu • PD_Met_HT_Btag_HSCP, SD_BTag_HSCP • For validation: asking to produce SD_BTag_HSCP also from QCD_Pt* BTag POG - October exercise

9. Data sets and skimming • No real need for a group skim – SD selections are sufficient • Open question: where will the SDs be located? • If necessary, replicate SDs to one or two b-tag Tier2s • Additional datasets • Only a subset of the MC samples will be transformed into SDs • The low pthat bins are not sufficient for systematic studies • we will have to do “private” SDs on a the remainingInclusiveMu5_Pt* (and potentially also on some) QCD samples • select the HLT paths mentioned before and store AOD on b-tag T2s • Data size • upper limits (all QCD + InclusiveMu5): • total RECO ~ 15 TB, total AOD ~ 5 TB • Sizes corresponding to current SD list: • RECO ~ 3 TB, AOD < 1 TB BTag POG - October exercise

10. Data sets and skimming • Some conclusions & questions after first tests • publication of skims into local DBS failed • seems to be fixed in the latest CRAB (pre-)release • T2-T2 links • we will need to transfer data between b-tag Tier2s • we have requested commissioning of the links but we haveno control on this item: • will the links be operational by the start of the exercise ??? BTag POG - October exercise

11. B-tag performance framework • Intermediate datasets for the efficiency measurements • all efficiency measurements use a common compact input data format • currently a root tree (about 1.5MB / 10k events) we are studying the option to migrate to a PATtuple • it will be produced at one T2 and copied to other sites • no heavy computations • first tests showed rates of 1Mev / hour • the main steps of the analyses do not depend on the GRID andcan be done in parallel on local clusters BTag POG - October exercise

12. Last step: distribution of results • Results: • one set of efficiency numbers and one set of mistag rates • Distribution: • Prepare the payloads & inject into DB • most probably only tables, no functions • Prepare cff fragments to allow their default use • Prepare examples on how to access them BTag POG - October exercise

13. Distribution of tasks • Data placement & production of “performance measurement” tuples • TB, WA • Efficiencies from System8 • Francisco Yumiceva, Pratima Jindal, Meenakshi Narain, Jason Keller • Efficiencies from PtRel • Mariarosaria D’Alfonso, Victor Bazterra, Cecilia Gerber, Chris Neu • Mistag rates • Daniel Bloch, Jeremy Andrea, Christina Ferro • Publication of results • TB, V. Bazterra We have started weekly coordination meetings with all the contributors BTag POG - October exercise

14. Backup BTag POG - October exercise

15. 2007 results • We quoted expected performance (as of statistical errors, mostly) in BTV-07-001 • Here just to see the ballpark BTag POG - October exercise