Error while use MadSpin to calculate pp > tW and decay

[KP.Xie]

Hello, when I tried to calculate tW associated production and decay at the LHC used MadSpin (in MadGraph2.3.3), there was something wrong.

the code I typed is as follows

define p = p b b~
generate p p > t w-
output tW
launch tW
4 (turn MadSpin on)

Then MadGraph can calculate the tw production X-section correctly, but when turned to decay, it said

Command "generate p p > t w- --no_warning=duplicate" interrupted with error:
NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > t w- WEIGHTED=4 @1. Please enter a valid process
Command "generate_events run_01" interrupted with error:
InvalidCmd : No processes generated. Please generate a process first.
quit

It seems that p was still in 4 flavors scheme, but I had defined p = p b b~ at the very first. I cannot solve this problem. Hope for your help, thanks!

[Olivier Mattelaer (olivier-mattelaer)]

Hi,

Sorry for the long waiting time, I tought that I fixed that (well) before the holliday but looks like not.

The main problem comes from the fact that you are doing a 5 flavor computation with a massive b which is inconsistent with a 5 flavor computation. The easiest way to have this working is to use the model
sm-no_b_mass
and everything should go trough.

I'm pretty sure that before the holliday I implement a way to have it work in your way to do the computation. But the easiest is to do this part in a proper way anyway.

Cheers,

Olivier

[KP.Xie (kpxie)]

Thank you very much!

[Olivier Mattelaer (olivier-mattelaer)]

Hi,

Ok the fix that I did before christmass was not exactly that one but very similar.
The next version should be able to handle your syntax (if you really want to use 5F with massive b)

Cheers,

Olivier

[KP.Xie (kpxie)]

Ha ha, you're so nice. I think I can't wait to try the new version!

Cheers,
Ke-Pan