diagram generation

[veretin]

Hi,

using minimal QCD example from manual

Vector q1,...,q20, k1,...,k20;
Set ext : q1,...,q20;
Set int : k1,...,k20;

Model QCD;
Particle qua,QUA, -2;
Particle gho,GHO, -1;
Particle glu,+3;
Vertex QUA,qua,glu: g;
Vertex GHO,gho,glu: g;
Vertex glu,glu,glu: g;
Vertex glu,glu,glu,glu: g^2;
EndModel;


Local gluglu1 = diagrams_(QCD, {glu}, {glu}, int, ext, 1, ‘WithEdges_’+‘OnShell_’+‘NoTadpole_’+‘NoSnail_’);

print+ss;
.end

I get error messages

    Shell_’+‘NoTadpole_’+‘NoSnail_’);
1.frm Line 21 --> Illegal character at this position: ‘WithEdges_’+‘OnShe
ll_’+‘NoTadpole_’+‘NoSnail_’)
1.frm Line 21 --> Illegal character at this position: ��WithEdges_’+‘OnShel
l_’+‘NoTadpole_’+‘NoSnail_’)
1.frm Line 21 --> Illegal character at this position: �WithEdges_’+‘OnShell
_’+‘NoTadpole_’+‘NoSnail_’)
...

Without last argument I produce some output (7 diagrams in this case).

Best regards,
Oleg Veretin

[jodavies]

Hi Oleg, at the moment the conversion to html for the manual messes up the quotes, if you replace them all with `' then it should work as expected.

[tueda]

https://form-dev.github.io/form-docs/stable/manual/ was generated with LaTeX2HTML, so it doesn't suffer from this conversion problem.

[veretin]

Thank you, that works!

One more question. What about vertices with N=2 (mixing)?

I tried this

    Model PHI3;
    Particle phi, +1;
    Particle psi, +1;
    Vertex phi,psi: g2;
    Vertex phi,phi,phi: g;
    EndModel;

But get error

*** illegal coupling const : nlegs - 2 + 2*loop: 2*loop = 1
*** Error : illegal value of c-constants

[jodavies]

Here the 2-pt vertex needs to have an even-power coupling symbol, it is not just a tag, grace cares about the powers.