Frequently Asked Questions: Normal Mode

This page includes remedies to the queries that we get on a daily basis. Hope the answer to your next question will be included here in the future.

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• How can I create a differential cross-section plot?

Okay, first of all, let's assume that you know what plots you want to prepare and you know that MadAnalysis assumes the cross-section is always in pb. So let's start running MadAnalysis.

$ ./bin/ma5

You should be able to see that all necessary functionality is available to you. Now import your sample and set its cross-section

ma5>import samples/zz.lhe.gz as my_sample
ma5>set my_sample.xsection = 123

note that if you press tab after set my_sample. you will see all the available options for the sample. Now let's plot transverse momentum for leading positron.

ma5>plot PT(e+[1])

Note that automatically this will create a selection

ma5>display selection[1]
MA5:   * Plot: PT ( e+[1] )
MA5:   * Binning: nbins=100, xmin=0.0, xmax=1000.0, regions=[]
MA5:   * Stacking method: stacked
MA5:   * Particles under consideration: finalstate
MA5:   * Particle ordering: PTordering

Note try pressing tab after everything, you will see available options'' By default, MadAnalysis is designed to plot the number of events, not cross-section so let's change the luminosity value to get the cross-section. Note that luminosity, by default, is always inverse fb. Also lets modify the y-axis label with proper units.

ma5>set main.lumi = 1e-3 * 10 # see the bin size up there
set selection[1].titleY = "#frac{d#sigma}{dp_{T}} [pb/GeV]"

Note that my rendering engine for histogramming is ROOT that's why I used ROOT's LaTeX convention if you have a different engine, make sure that you are using proper LaTeX convention. And here is the final result: