ATLAS computing and MC

Notebooks!

Most of my cool non-ATLAS specific stuff can be found on my notebooks page. There's very little chance I would ever recommend anyone tries to follow what's on here if at all possible. That page contains notes on Machine learning, RooStats and remote links to ipython powered super clusters.

ATHENA

ATHENA was the greek godess of bad particle physics code. In her honour a huge monument was constructed to embody the great principles which she stood for.

Athena should be used in the following circumstances:

• you want to run your analysis on (D)xAODs as input
• you want to make a tool dual use or contribute to the offline software reconstruction
• you want to run detector simulations or access detector level information
• you want to run standardised software libraries rather than setting up each from scratch

I need to do the latter two items so therefore I will be running Sherpa and Madgraph 5 in Athena

Monte Carlo Generators

MC is how we model phyiscs processes in high energy physics. Several different generators exist but all follow key steps.

• Physics. The Matrix Element for the process is calculated taking into account order and pdf.
• Showering. Due to colour effects, partons from the hard interaction radiate gluons as they separate. Some generators do not shower the processes they predict. Often the hadronisation of particles is also separate.
• Underlying Event, Multiple Parton Interactions
• Detector simulation, reconstruction, Pile Up etc

I will focus on Sherpa which produce ME, matches partons and Showers all internally; and Madgraph5 with aMC@NLO which produces ME and then needs to be showered through Pythia8.

If there is time in the summer I will extend the notes on this page with some studies regarding detector simulation and possibly reconstruction

Generating Events with Madgraph + aMC@NLO + Pythia8

In this example we use Madgraph to calculate processes aMC@NLO to calculate matrix elements and Shower through Pythia8. I'm following the examples listed on the Madgraph ATLAS Twiki written by Josh McFayden at UCL

As described to set up Generation with Athena, there are some compilation required when setting up.

cd workdir
setupATLAS
asetup 19.2.5.1,here
cmt co -r MadGraphControl-00-05-33 Generators/MadGraphControl
cd Generators/MadGraphControl/cmt
make clean; make
cd ../../../
mkdir analysisdir

after this the regular JO's should work in the analysisdir