Changes between Version 6 and Version 7 of Density

Timestamp:

Oct 24, 2025, 11:39:15 AM (5 days ago)

Author:

Durupt

Comment:

--

Density

@@ -22 +22 @@
 }}}
 
-The user is then asked to edit the different cards needed for the run. The information for the density matrices computation is given in the reweight_card. Examples for different benchmark processes are given in https://arxiv.org/abs/2510.17730.
+The user is then asked to edit the different cards needed for the run. The information for the density matrices computation is given in the reweight_card. Examples for different benchmark processes are given in https://arxiv.org/abs/2510.17730. At the end of the run, the density matrix for each event is written in the Les Houches Event (LHE) file.
+
+==How to read the density matrices in the LHE file
+The LHE file can be read with the parser lhe_parser.py available in MadGraph. An example of code that would parse the density matrix value for each event is:
+
+{{{
+import sys
+sys.path.append('PATH TO MADGRAPH')
+import madgraph.various.Density_functions as dens
+import madgraph.various.lhe_parser as lhe_parser
+
+lhe_path = os.path.join('PATH TO MADGRAPH', Data_Path)
+for event in lhe_parser.EventFile(lhe_path):
+    density = event.density
+    square_density = dens.square_matrix(density)
+
+}}}
+
+With this code, for each event of the file, you read the value `density` which contains the independent coefficients of the density matrix. The utility function `square_matrix` allows to write it in the usual matrix form needed for further analysis.
+