Changes between Version 2 and Version 3 of MC4BSM

Timestamp:

Mar 6, 2012, 10:25:34 PM (13 years ago)

Author:

Olivier Mattelaer

Comment:

--

MC4BSM

@@ -104 +104 @@
      5. Restart the chain but this time by including all the decay chain in MG5.
 
-     Note that in order to have the correct cross-sections in the second cases or to have the correct branching ratio computed by Pythia in the first case, we need first to compute the width and the branching ratio of the non standard model particles. 
+   Note that in order to have the correct cross-sections in the second cases or to have the correct branching ratio computed by Pythia in the first case, we need first to compute the width and the branching ratio of the non standard model particles. 
  
-  * '''The model'''[[BR]]
+   * '''The model'''[[BR]]
+     The simple way to have access to a model in MG5 is to put in the directory: MG5_DIR/models
+     after that you can simply import it in MG5 by doing 
+{{{
+   import model MODELNAME
+}}} 
+     or 
+{{{
+   import model MODELNAME --modelname
+}}} 
+     The option --modelname tells MG5 to use the name of the particles defines in the UFO model, and not the usual MG5 conventions for the particles of the SM and the MSSM. In principle this shouldn't change anything in the model that you load.
+     For the first time that you import a new model, it's allow a good points to test it. For this 
+     1. It's advice to run MG5 in debug mode (./bin/mg5 --debug)
+     2. It's useful to test the Lorentz invariance/Gauge invariance/... of at least a couple of processes. This is one examples:
+{{{
+   import model MODELNAME
+   check p p > urv urv~
+}}}
+
+   * ''' Computation of the width and branching ratio'''
+     The first element in order to have a valid generations is to have valid input parameters. This includes in particular to have the correct width (and the correct branching ratio for Pythia).
+     If you tell all the channel of desintegration, MG5 is able to compute all those parameters.
+{{{
+   import model MODELNAME
+   generate urv > u p1
+   add process urv > u p2
+   add process [ADD all 1->2 decay and relevant 1->3 decay, for both interesting particles]
+   output 
+   launch
+}}}
+   This will creates to you one valid param_card with the computed width and the computed branching ratio.
+   Note that the solution (and the valid files to produces it are in attachment of this page)
+
+  * '''Generation of events (Decay done in pythia)'''
+{{{
+   import model MODELNAME
+   generate p p  > urv urv~
+   output
+   launch
+}}}    
+    One of the questions will be to ask you if you want to edit the param_card. At this stage, you can enter the path of the previously created param_card.dat.
+ 
+  * '''Generation of events (Decay done in MG5)'''
+    Add the decay in MG5 (such that the full spin correlation is taken into-account) and generate events.
+    In order to learn the syntax of the decay chain. Please type
+{{{
+    help generate
+}}}
+    Solution in attachments.
 
 
 
 
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+     
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