# Information about calculation of the cross setion in Whizard

Dear Whizard support,

Is it possible to get information about how the cross section is calculated for various processes in Whizard ?

Suppose I study the process "e+ e- -> N1 ve" using SM_HeavyN_NLO model:

model = SM_HeavyN_NLO (ufo)

mN1 = 500 GeV

process eE_N1ve = em, ep => N1, ve

compile

sqrts = 800 GeV

beams = em, ep

integrate(eE_N1ve) {iterations = 10:100000}

And I get the corresponding values of Integral[fb] and Error[fb]:

| Starting integration for process 'eE_N1ve'
| Integrate: iterations = 10:100000
| Integrator: 3 chains, 3 channels, 2 dimensions
| Integrator: Using VAMP channel equivalences
| Integrator: 100000 initial calls, 20 bins, stratified = T
| Integrator: VAMP
|=============================================================================|
| It Calls Integral[fb] Error[fb] Err[%] Acc Eff[%] Chi2 N[It] |
|=============================================================================|
1 95256 3.0990073E+04 6.40E+00 0.02 0.06* 11.02
2 95256 3.0999645E+04 6.38E+00 0.02 0.06* 11.02
3 95256 3.0988672E+04 6.35E+00 0.02 0.06* 11.02
4 95256 3.0987977E+04 6.33E+00 0.02 0.06* 11.02
5 95256 3.0987538E+04 6.40E+00 0.02 0.06 11.02
6 95256 3.1007277E+04 6.26E+00 0.02 0.06* 11.02
7 95256 3.0997888E+04 6.49E+00 0.02 0.06 11.02
8 95256 3.0991739E+04 6.32E+00 0.02 0.06* 11.02
9 95256 3.0998517E+04 6.42E+00 0.02 0.06 11.02
10 95256 3.0991267E+04 6.47E+00 0.02 0.06 11.02
|-----------------------------------------------------------------------------|
10 952560 3.0994084E+04 2.02E+00 0.01 0.06 11.02 1.05 10
|=============================================================================|

So, is there a toolkit that allows you to see the calculations of these quantities themselves?

Thanks and all the best,

Evgeny

## Question information

Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
Last query:
 Revision history for this message Juergen Reuter (j.r.reuter) said on 2023-03-26: #1

Dear Evgeny,
I'm sorry to say that I didn't get your question: do you want to understand how a Monte Carlo event generator in general works?
Please take a look at the manual and at general literature, and then maybe ask more concrete questions.
Best,
JRR (Juergen)

 Revision history for this message Juergen Reuter (j.r.reuter) said on 2023-04-05: #2

Marking as solved for the moment. Please open a new issue in case you have a more concrete question.