Calchep as matrix element generator

Asked by Safinaz

Hi authors,

May I ask when I use :

In[1]:= <<"../sum_22.m"
In[2]:= <<"symb1.m"
In[3]:= sum

the Mandelstam variables in the expression I get are in parton or Hadron level ? I mean for s variable
for example: s = x1 x2 E^2_CME or s = E^2_CME (14000^2, LHC) ..

Also after using sum_int.m program, it's made an integration to get the total cross section, so
how I substitute " be$ " symbol and " s "variable I get now in the yielded formula ..


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Alexander Pukhov (pukhov) said :

Sorry for delay.
Mandelstam variables correspond to parton level momenta.
Parameter be^2 is defined in sum_int.m

 beSquared =Simplify[16*(E1cm^2-MM1)*(E3cm^2-MM3)/s^2];

One can use it to substitute "be". As a rule this substitution increases size of expression.
So we pass this step to the user.

Happy New Year!

Alexander Pukhov

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Safinaz (sramadan) said :

Hi Dr. Alexander,

Thanks for reply, I will try this.

Happy New Year


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Alexander Belyaev (alexander.belyaev) said :

Could you reply us,please if this solved your problem?
Alexander Belyaev

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