Higgs-to-four-lepton analysis example using 2011-2012 data

How can you use this?

In addition to the instructions below which guide you through the example in detail, a github repository based on this original example is also provided. The root files needed for the Level 3 exercise can be found here.

There are four levels of increasing complexity for this example:

1. Compare the provided final output plot mass4l_combine.pdf or mass4l_combine.png to the published one, keeping in mind the caveats mentioned in this record.
2. Reproduce the final output plot from the predefined histogram files using a root macro (~few minutes - ~few hours, depending on setup and proficiency)
• if a ROOT version on the local computer compatible with ROOT 5.32/00 is running, use the local version (avoids installation of VM). Otherwise, follow the instructions in CMS 2011 Virtual Machines: How to install up to and including the command 'cmsenv', in order to install the VirtualBox and the CMS Open Data VM, and run ROOT there (the validation step with the Demo example may be skipped)
• if not already proficient in ROOT, consider doing a brief ROOT introductory tutorial in order to understand what the root macro will do
• create a new directory, e.g. rootfiles mkdir rootfiles
• switch to that directory cd rootfiles and download the preproduced *.root histogram files given in this record for all relevant samples to this directory
• Alternatively, on the command line in the directory rootfiles, type wget http://opendata.web.cern.ch/record/5501/files/rootfilelist.txt and then wget -i rootfilelist.txt
• If you wish, you may look at the content of these files using ROOT: e.g. type root, and on the root promt, type TBrowser t, then double-click on the relevant file
• download the root macro M4Lnormdatall.cc from this record into the same directory
• on the linux prompt, type root -l M4Lnormdatall.cc
• you will get the output plot on the screen
• either, on the ROOT canvas (picture) click file->Quit ROOT or, on the root [] prompt, type .q
• you will exit ROOT and find the output plot in mass4l_combined_user.pdf
• you can compare this plot with the plots provided in 1.
3. Produce a root data input file from original data and MC files for one Higgs signal candidate and for the simulated Higgs signal with reduced statistics (for speed reasons) and reproduce the final output plot containing your own input using a root macro (~1 hour if Virtual machine is already installed, depending on internet connection and computer performance, up to ~few hours otherwise)
• if not already done, follow instructions for steps 1 and 2 in CMS 2011 Virtual Machines: How to install, including the installation of the demo analyzer
• in the Demo/DemoAnalyzer/ directory, which is created following Step 2: How to test and validate, replace BuildFile.xml by the version downloaded from this record
• download HiggsDemoAnalyzer.cc from this record to the Demo/Demoanalyzer/src subdirectory
• in Demo/DemoAnalyzer/, recompile scram b
• download demoanalyzer_cfg_level3data.py (data example) and demoanalyzer_cfg_level3MC.py (Higgs simulation example)
• create datasets directory mkdir datasets and change to this directory cd datasets
• download the 2012 JSON validation file from the corresponding record to this directory
• if not yet done at level 2, create the directory rootfiles and download all the level 2 root files to this directory (see level 2)
• run the two analysis jobs (one on data, one on MC, the input files are already predefined)
• cmsRun demoanalyzer_cfg_level3data.py will produce output file DoubleMuParked2012C_10000_Higgs.root containing 1 Higgs candidate from the data
• cmsRun demoanalyzer_cfg_level3MC.py will produce output file Higgs4L1file.root containing the Higgs signal distributions with reduced statistics
• move the two .root files above to the rootfiles directory, together with the predefined files
• mv DoubleMuParked2012C_10000_Higgs.root rootfiles/.
• mv Higgs4L1file.root rootfiles/.
• change directory cd rootfiles and download the macro M4Lnormdatall_lvl3.cc to this directory
• on the linux prompt, type root -l M4Lnormdatall_lvl3.cc
• you will get the output plot on the screen; the magenta Higgs signal histogram will now be the one you produced, and the one data event which you have selected will be shown as a blue triangle. All other parts of the plot are the same as in 2.
• either, on the ROOT canvas (picture) click file->Quit ROOT or, on the root [] prompt, type .q
• you will exit ROOT and find the output plot in mass4l_combined_user3.pdf
4. Reproduce the full example analysis (up to ~1 month or more on single CPU with fast internet connection, depending on internet connection speed and computer performance)
• start by running level 3 and understand what you have done
• download demoanalyzer_cfg_level4data.py and demoanalyzer_cfg_level4MC.py from this record
• at this level, instead of running over a single file, you will run over so-called index files which contain chains of files
• download all the data index files for the datasets listed in List_indexfile.txt to the datasets directory (you can find the links to the datasets in this record)
• download the 2011 JSON validation file to the datasets directory (in which you should already have the 2012 one)
• download all the MC index files for the MC sets listed in List_indexfile.txt to the MCsets directory (after having created it)
• edit the relevant demoanalyzer_cfg file and insert the index file you want; for data, make sure to use the correct JSON validation file in each case; set an output file name of your choice for each sample which you will recognise
• run the analysis job (cmsRun demoanalyzer_cfg_level4...) sequentially on all the input samples listed in List_indexfile.txt, i.e. produce all root output files yourself. If you have access to a computer farm with local support for the installation of the CMS software (the Open Data team can only provide support for the single virtual machine mode), you may also run the analysis in parallel on different CPUs, correspondingly speeding up the result.
• merge all the files from different index files of a dataset by using root tools
• If everything ran correctly, at this stage the content of your rootfiles should be identical to the one in the predefined rootfiles. If you don't want to run everything, you can also run only some of the datasets (but all events of all index files of a dataset must be treated and merged), and use the predefined ones for the others.
• go to 2., using your own root output files instead of the predefined ones, i.e. edit the file M4Lnormdatall.cc accordingly. If everything worked correctly you should get an output identical to mass4lcombine.pdf, but now using your own files.

Source code repository