Frequently Asked Questions: Normal Mode

MOTTO: Tab is your friend, use it!

Second MOTTO: Read the reference card and the manual, they are your friends too!

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 let's modify the y-axis label with proper units.

ma5>set main.lumi = 1e-3 * 10 # see the bin size up there
ma5>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 the proper LaTeX convention. And here is the final result:

Note that if I wanted to use Matplotlib as my graphic renderer I could have chosen using set main.graphic_render = matplotlib command, given that matplotlib is available in the system. Then the title should be modified as follows set selection[1].titleY = "$\\frac{d\\sigma}{dp_{T}}\ {\\rm [pb/GeV]}$" since this is following the matplotlib's LaTeX convention.

Where do I see all the plot options?

1) press the tab after typing the plot.

2) Read the reference card in your local madanalysis/doc folder.

How can I modify my plot?

Plots are stored under selection objects so first check which selection your plot is in by typing display selection. Once you find the selection ID, lets say 1 simply type set selection[1].<tab> and you will see all the available options to play with.

How can I modify my sample

First import your sample import my_sample.lhe as my_sample then type set my_sample.<tab> to see all available options.