To do calculation for polarizations

To do calculation for polarizations, the user should understand a little bitter about the spin setting. The spin setting is as following:

  namel   :='(ef  efb wb  h0  w);                 
  spin    :=  ns1 ns2 nn3 nn4 nn5

where "ns1,ns2,......" is for fermions and "nn1,nn2,......" is for boson. There are two state of fermion spin, the two state denoted as "1", "2". There is only one state for scalar boson so that nn4 could not changed. For vector boson, the two transverse spin polarization state are express as "x", "y". It is also another two polarization state "er" and "el" which could be defined from "x", "y" as

$$\begin{eqnarray*} & er={\displaystyle x+iy \over \displaystyle \sqrt 2} & el={\displaystyle x-iy \over \displaystyle \sqrt 2} \end{eqnarray*}$$

For massive vector boson, there is an additional longitude polarization state is denoted as "z".

To describe the polarizations. The format of each line is

    ( spin_1 ... spin_n m1 ... m) 

 where spin_i=(nni s), 
       s=1,2 and nni=ns1,ns2.... for fermions. 
       s=x,y,z or er,el,z. nni=nn1,nn2.... for vector boson.  
       m1, ...., m means the order number of each distributions  
                 to be ploted, which is described in last section,
                 and 0 means the total cross section.

There is an example in the following. to do the calculation for polarization, one has to add the following part to the input file "process.def".

where the first line (0 5 6) mean to calculate the total cross section, the distribution 5 and 6 without polarization. The second line mean to calculate the total cross section and the distribution 1, 2 and 3 with the first particle (electron) polarization ns1=1, the third particle ($w^-$) polarization nn3=x, and the other particles are not polarized. The other line can also be explained in the same way.