Ntuple analysis skeleton

The tree files that make up the Analysis Skeleton

The Analysis of the Root ntuple proceeds in a very straightforward way. Inside ROOT we used MakeClass() to get the .h and .C files. These were extended to our needs and together the following three files form the analysis skeleton:

1) simpleTTbarAnalysis.h

The standard header file extended with the implementation of a few routines the user is not expected to change often

2) simpleTTbarAnalysis.C

The user analysis-file where the user:

o reads in the event

o fills vectors with 'good' physics objects (leptons, jets, photons etc. passing the user's quality requirements)

o performs the top-analysis. The resulting histograms will be written out in a separate root file

3) simpleNtupleTTbarAnalysis.C

The steering-file containing the location of the ntuples and a function that decides:

o what ntuples to process

o how many events to process

o extension to the name of the output file

How to run the skeleton analysis is ROOT

The first step is to correctly set the location of your ntuples in the file simpleNtupleTTbarAnalysis.C. Then, to analyse the first 100 events in ntuple-set 1 and to store the output histograms in a file called summary_ttbar_full_test.root simply open a root session and do:

  Root>  .L simpleTTbarAnalysis.C++;

  Root>  .x  simpleNtupleTTbarAnalysis.C(1,100,"test");

When setting the number of events to "-1", all events are processed.