MCatNLO Step 2

In this step we will have MCatNLo produce $t{\bar {t}}$ events-files. To do this we will:

• Build the executable
• Construct the BASIC input files
• Produce X event files containing Y events each using automated scripts

1) Build the executable

First go the the directory with the MCatNLO code:

cd /MyMCatNLO/EXECUTABLE/

Then construct an input file in the same way as you did for the integration step.

cp MCatNLO.inputs.Integration MCatNLO.inputs.EventGeneration

In this file you only need to change one line:

BASES=OFF

The build the executable, first remove the directory called Linux (this contains the executable that was used for the integration step). After that, simply build the executable:

rm -Rf Linux 
./MCatNLO.inputs.EventGeneration

This will create in a directory called Linux the executable called TTbarNLO_EXE_THISLIB

Copy the executable to the BASIC directory

To have all necessary file together for the event generation, also save the executable in the 'BASIC' directory where you have stored the results from the integration.

cp ./Linux/TTbarNLO_EXE_THISLIB ./../CTEQ5M1_BASICS/

2) Run the executable (simple try)

To run the executable you are required to have in the directory from where you launch the job:

o the information from the integration step

o the PDF

By doing the integration step we have already these files in the running directory. Furthermore, when running the executable, again you are asked for many input variables. To automate this please create a new input file.

cp ./Integrationstep.inputfile ./Eventgenerationstep.inputfile

As a first run, you only have to say you do not need the integration anymore In the input file you therefore have to change the values for itmx1 and itmx2:

  0 0                                                   ! itmx1,itmx2

You can of course also set the Number of events to whatever you like say (100) and plug in your favorite seed for the random numbers (say 1234567).

running the executable To run the executable simply do:

./Linux/TTbarNLO_EXE_THISLIB < Eventgenerationstep.inputfile

This is extremely fast and for each run three files will be produced:

  TTbarProd.events
  TTbarProd_a.events   
  TTbarProd_b.events

The file TTbarProd.events contains the 100 events you have generated and the "_a" and "_b" files are subsets that contain the events that respectively did and did not radiate a hard gluon.

3) Run the executable (the real thing more automated)

To automate this we created a small script that allows you to generate sets of events. A first thing to do is to save the executable and the input file in the BASICS directory:

  cp ./Linux/TTbarNLO_EXE_THISLIB   ./../CTEQ5M1_BASICS/
  cp Eventgenerationstep.inputfile  ./../CTEQ5M1_BASICS/

Creating a basic input file that can be manipulated by the scripts Since for each run the script will change the name of the output file, the number of events and the seed for the random numbers, the input file should contain some tags that can be read by the script so a unique input file can be created for each run.

Go to the BASICS directory:

  cd /MyMCatNLO/CTEQ5M1_BASICS/
  mv Eventgenerationstep.inputfile Eventgenerationstep.inputfile.BASIC 

Change the following lines in Eventgenerationstep.inputfile.BASIC