Package madgraph :: Package interface :: Module tutorial_text_madloop
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Source Code for Module madgraph.interface.tutorial_text_madloop

  1  ################################################################################ 
  2  # 
  3  # Copyright (c) 2009 The MadGraph5_aMC@NLO Development team and Contributors 
  4  # 
  5  # This file is a part of the MadGraph5_aMC@NLO project, an application which  
  6  # automatically generates Feynman diagrams and matrix elements for arbitrary 
  7  # high-energy processes in the Standard Model and beyond. 
  8  # 
  9  # It is subject to the MadGraph5_aMC@NLO license which should accompany this  
 10  # distribution. 
 11  # 
 12  # For more information, visit madgraph.phys.ucl.ac.be and amcatnlo.web.cern.ch 
 13  # 
 14  ################################################################################ 
 15   
 16  tutorial_MadLoop = """ 
 17  You have entered tutorial mode. This will introduce you to the main 
 18  syntax options for MadLoop which are mostly similar to the MadGraph5_aMC@NLO one.  
 19  If you have not done so already, please follow MadGraph5_aMC@NLO tutorial before  
 20  this one.   
 21   
 22  Remember that exactly as in MadGraph5, you can learn more about the different  
 23  options for any command by typing 
 24  MG5_aMC> help A_CMD 
 25  And to see a list of all commands, use 
 26  MG5_aMC> help  
 27   
 28  MadLoop is the part of MadGraph5_aMC@NLO used to generate the code for 
 29  evaluating the loop diagrams. This tutorial teaches you how to use MadLoop 
 30  as standalone tool for studying loops within particular processes. 
 31  Therefore in this mode, you can only consider definite processes, meaning  
 32  without multiparticle labels. 
 33   
 34  This tutorial has three parts: 
 35  a) How to generate a process. 
 36  b) How to cross-check / profile an output. 
 37  c) How to compute the loop matrix element squared for local phase-space points. 
 38   
 39  Let's start with the first point, how to generate a process with MadLoop in 
 40  standalone mode. Keep in mind that this means only the loop and born diagrams 
 41  are generated. 
 42   
 43  MG5_aMC>generate g g > d d~ [virt=QCD] 
 44   
 45  Note that a space is mandatory between the particle names and that '[virt=QCD]'  
 46  specifies that you want to consider QCD NLO corrections. The keyword option 
 47  'virt' before '=' within the squared brackets precisely specifies you are only 
 48  interested in the virtual contribution.   
 49  """ 
 50   
 51  tutorial = tutorial_MadLoop 
 52   
 53  generate = """ 
 54  You have just generated a new process. 
 55  You can find more information on supported syntax by using: 
 56  MG5_aMC>help generate 
 57  To list all defined processes, type 
 58  MG5_aMC>display processes 
 59   
 60  You can display a pictorial representation of the diagrams with  
 61  MG5_aMC> display diagrams 
 62  Notice you can add the option 'loop' or 'born' if you only want those diagrams 
 63  to be displayed. 
 64   
 65  If you want to add a second process, you can use the add process command: 
 66  MG5_aMC>add process e+ e- > d d~ [virt=QCD] 
 67  But keep in mind that you must still consider only virtual corrections and  
 68  cannot employ multiparticle labels. Also decay chains are not available for 
 69  loops. 
 70   
 71  At this stage you can export your processes. 
 72  This is done simply by typing: 
 73   
 74  MG5_aMC>output MY_FIRST_MADLOOP_RUN 
 75   
 76  Notice that the standalone output mode (implicit in the above) is the only 
 77  available for MadLoop standalone runs. 
 78  """ 
 79   
 80  display_processes = """ 
 81  You have seen a list of the already defined processes. 
 82   
 83  At this stage you can export your processes to different formats.  
 84  To create a MadLoop standalone output for these, simply type: 
 85   
 86  MG5_aMC>output MY_FIRST_MADLOOP_RUN 
 87  """ 
 88   
 89  display_diagrams = """ 
 90  You have displayed the diagrams. 
 91  Notice you can add the 'born' or 'loop' option to this command to specify the 
 92  class of diagrams to be displayed. 
 93   
 94  At this stage you can export your processes to different formats.  
 95  To create a MadLoop standalone output for these, simply type: 
 96   
 97  MG5_aMC>output MY_FIRST_MADLOOP_RUN 
 98  """ 
 99   
100  add_process = """ 
101  You have added a process to your process list. 
102   
103  At this stage you can export your processes. 
104  For this, simply type 
105   
106  MG5_aMC>output MY_FIRST_MADLOOP_RUN 
107  """ 
108   
109  output = """ 
110  If you are following the tutorial, a directory MY_FIRST_MADLOOP_RUN has 
111  been created under your MadGraph5_aMC@NLO installation directory. 
112   
113  The code for the evaluation of the squared loop matrix element is in  
114  'SubProcesses/P0_<shell_proc_name>/'. There, you can compile and edit  
115  running parameters from 'MadloopParams.dat' and then run the code with './check' 
116  Alternatively, for a simple quick run, type: 
117   
118  MG5_aMC>launch -f 
119   
120  This computes the squared matrix element for a given PS points. 
121  For the purpose of this tutorial, the option '-f' is added to automatically skip 
122  the edition of the cards and phase-space point specification. 
123  """ 
124   
125  launch = """ 
126  You just launched the MadLoop standalone evalutation of the squared loop matrix 
127  element for (a/many) specific process(es) for a random Phase-Space point. 
128  The two processes proposed in this tutorial were g g > d d~ and e+ e- > d d~. 
129  You can check that you get the right double pole normalized with respect to 
130  the born*(alpha_s/2*pi), namely -26/3 and -8/3 respectively. 
131   
132  Now this tutorial will introduce you to two checking functionalities for the 
133  evaluation of the contributions of virtual origin. 
134  Start by typing: 
135   
136  MG5_aMC>check g g > d d~ [virt=QCD] 
137   
138  This will test lorentz and crossing invariance as well as of the gauge  
139  invariance check from the ward identity for the initial state gluon. 
140  You can add an option after check to specify to perform only one definite check. 
141  Notice that the check functionality is only available for MadLoop standalone 
142  runs (those with the 'virt=' option). 
143  """ 
144   
145  check = """ 
146  You have seen the results for the various consistency checks performed on the 
147  MadGraph5_aMC@NLO loop computation. 
148  You can now use the check command to obtain a full profiling of a given process 
149  including loop contributions. 
150  Simply type: 
151   
152  MG5_aMC>check profile g g > d d~ [virt=QCD] 
153   
154  Notice that you can replace 'profile' by 'timing' or 'stability' if 
155  you only want timing or stability benchmarks about this process. 
156  """ 
157   
158  check_profile = """ 
159  You have seen detailed information about the stability, timings and code size 
160  of a given process including loop. 
161  Keep in mind that these check functionalities are only available for MadLoop 
162  standalone runs. 
163   
164  You just learned the basic commands for the MadLoop runs (i.e. with the  
165  'virt=' option). You can close this tutorial by typing 
166  MG5_aMC>tutorial stop 
167  Or exit MG5 with 
168  MG5_aMC>exit 
169  """ 
170