CMS like artificial smearing

The jet energy resolution (JER) is measured in the CMS events as a function of eta, pT of the jets and of the pile-up density rho. Rho is a measurement of the quantity of additional energy deposited in a jet by the pile-up.

The resolution is parametrised with a continuous function with respect to the jet pT, and the coefficients of the continuous function vary in bins of eta and rho. One file containing values for this parameterisation can be found here, while some code to read it and use it in here.

The files are the following:

• JERfile.txt is the input information
• JERreader.* is the class reading the txt file and returning the JER, in percentage of the jet pT
• unit01: trivial example
• unit02: slightly less trivial example
• unit03: draw some resolution lines

Two functions are implemented in the JERreader class, both called "resolution". The one with two arguments assumes a fixed value of rho, which starts at 30., and can be modified later on with the changeRho method of the class.