Changes between Version 4 and Version 5 of FormFactors


Ignore:
Timestamp:
12/07/13 14:03:51 (6 years ago)
Author:
omatt
Comment:

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  • FormFactors

    v4 v5  
     1=== How to add momentum dependent form factors? in UFO model===
     2
     3=== Compatible model.
     4
     5All UFO model are not ready to use form-factor (all recent one should be).
     6In order to see if your model is compatible, look in the file __init__.py
     7if you see the following lines:
     8{{{
     9try:
     10   import form_factors
     11except ImportError:
     12   pass
     13else:
     14   all_form_factor = form_factors.all_form_factors
     15}}}
     16
     17=== Defining your form factor:
     18
     19create/edit the file form_factors.py
     20and add the following lines:
     21{{{
     22from object_library import all_form_factors, FormFactor
     23
     24from function_library import complexconjugate, re, im, csc, sec, acsc, asec, HeavTheta
    125
    226
    3 === How to add momentum dependent form factors? ===
     27
     28AAA = FormFactor(name = 'AAA',
     29                 type = 'real',
     30                 value = 'HeavTheta(MH - P(-1,1)*P(-1,3),-2*MH*,MH)')
     31}}}
     32
     33  1. HeavTheta is a special function for a IF statement. If the first argument is positive then the function is equal to the second argument otherwise the function is equal to the third argument.
     34  2. Any parameter of the model can be used inside the 'value' expression
     35  3. You can use any type of object define in the ALOHA syntax (see the [ALOHA paper http://arxiv.org/abs/arXiv:1108.2041] for the convention). This includes the momenta P(x,y). This first index is the lorentz index which should be contracted, while the second index refers to the particle ordering of the vertex.
     36  4. If you need to add an additional parameter in your model, you can do it in the parameters.py file.
     37
     38
     39=== Add the vertex dependencies in your form factor:
     40
     41For later...
     42
     43
     44
     45=== How to add momentum dependent form factors? in v4 model===
    446The easiest way to implement momentum dependent form factors, without changing all the details in the
    547{{{