1. B-Tagging Common Interface Y.D. Mutaf, S. Towers 20 March 2003 H b _b

2. 03/20/03, Higgs WGY. Mutaf1 Motivation The taggers are currently provided by some macros specific to different data formats (TMB, TMBTree etc.) Due to different developers, the interfaces to these macros are quite different Increases the “messiness” index of the user analysis code –A clear sign of inefficient coding (from the user’s perspective) Time spent to learn different implementations is a waste We need a common interface, common ground B-id group recently started an effort for combining all the tagger algorithms in one package with the same interface

3. 03/20/03, Higgs WGY. Mutaf2 “btags_cert” package Initially designed for doing smearing of MC track information related to jets, in order to make MC look more like our data (will talk about this later) It now includes a common interface to Impact Parameter and Secondary Vertex B-tagging macros/code Not “heavily” advertising its use, since this method will become obsolete when the B-id group’s package comes along However this is a utility we will use for the near future

4. 03/20/03, Higgs WGY. Mutaf3 B-tagging Methods Secondary Vertex Tagging –A jet is tagged if there is an associated secondary vertex Soft Lepton Tagging –Relies on the identification and properties of the lepton from the leptonic decay of the B-meson. Impact Parameter Tagging –Assigns a combined probability to the jet using the associated tracks for belonging to the Primary Vertex –Counting Signed IP tagging is a variation PV SV N/A

5. 03/20/03, Higgs WGY. Mutaf4 Implementation Btagger object is the driving source of the taggers. Switches and cases are eased with the use of enumerations. Contains a pointer to an abstract base class through which we will access the individual tagger classes.

6. 03/20/03, Higgs WGY. Mutaf5 Tag Classes Pure virtual methods that are implemented by the daughter classes Everything is defined in “btags_cert” namespace

7. 03/20/03, Higgs WGY. Mutaf6 Implementation The package has an example directory which contains an example package accessing TMB chunks… Most of the tagging related parameters are driven by package owned RCPs. Can give more info if anyone needs to use for immediate purposes…

8. 03/20/03, Higgs WGY. Mutaf7 Example Package The “btags_cert” package contains an example directory which contains a full example package to do the implementation of this package in TMB’s Need to copy the example package into the working release are ($SRT_PRIVATE) There is more to do before hand (due to requirements from the individual taggers), we’ll talk about these

9. 03/20/03, Higgs WGY. Mutaf8 More on the Example Instantiation of the individual taggers Through the enumerations…

10. 03/20/03, Higgs WGY. Mutaf9 More on the Example Need to feed the PV information before using the taggers Reading the tracks from the event… One can directly feed the tracks as well. Need to reset all the information in the taggers before the next event.

11. 03/20/03, Higgs WGY. Mutaf10 More on the Example Doing the tagging which, “for now” returns a three-fold quality ie. LOOSE, MEDIUM and TIGHT. Will soon add methods to return a continuous variable eg. Probability The method uses a “jetid::Jet” but it can also accept two values of jet direction ie. eta, phi.

12. 03/20/03, Higgs WGY. Mutaf11 Things need to be done beforehand… Follow the instructions for the packages to be compiled needed for the SVTX tagging (even if you don’t use it) I am not sure if “all” the packages are needed! Try and let me know…