Changes between Version 2 and Version 3 of MC4BSM


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Timestamp:
03/06/12 22:25:34 (6 years ago)
Author:
omatt
Comment:

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  • MC4BSM

    v2 v3  
    104104     5. Restart the chain but this time by including all the decay chain in MG5. 
    105105 
    106      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.  
     106   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.  
    107107  
    108   * '''The model'''[[BR]] 
     108   * '''The model'''[[BR]] 
     109     The simple way to have access to a model in MG5 is to put in the directory: MG5_DIR/models 
     110     after that you can simply import it in MG5 by doing  
     111{{{ 
     112   import model MODELNAME 
     113}}}  
     114     or  
     115{{{ 
     116   import model MODELNAME --modelname 
     117}}}  
     118     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. 
     119     For the first time that you import a new model, it's allow a good points to test it. For this  
     120     1. It's advice to run MG5 in debug mode (./bin/mg5 --debug) 
     121     2. It's useful to test the Lorentz invariance/Gauge invariance/... of at least a couple of processes. This is one examples: 
     122{{{ 
     123   import model MODELNAME 
     124   check p p > urv urv~ 
     125}}} 
     126 
     127   * ''' Computation of the width and branching ratio''' 
     128     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). 
     129     If you tell all the channel of desintegration, MG5 is able to compute all those parameters. 
     130{{{ 
     131   import model MODELNAME 
     132   generate urv > u p1 
     133   add process urv > u p2 
     134   add process [ADD all 1->2 decay and relevant 1->3 decay, for both interesting particles] 
     135   output  
     136   launch 
     137}}} 
     138   This will creates to you one valid param_card with the computed width and the computed branching ratio. 
     139   Note that the solution (and the valid files to produces it are in attachment of this page) 
     140 
     141  * '''Generation of events (Decay done in pythia)''' 
     142{{{ 
     143   import model MODELNAME 
     144   generate p p  > urv urv~ 
     145   output 
     146   launch 
     147}}}     
     148    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. 
     149  
     150  * '''Generation of events (Decay done in MG5)''' 
     151    Add the decay in MG5 (such that the full spin correlation is taken into-account) and generate events. 
     152    In order to learn the syntax of the decay chain. Please type 
     153{{{ 
     154    help generate 
     155}}} 
     156    Solution in attachments. 
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