CKM matrix and the order of fields in Yukawa interactions

[WojciechKotlarski]

Hi Florian,

I'm continuing to experiment with SPheno versions with CKM matrix. What I observe is that whether or not of diagonal (tree-level) decays work is connected with the order of fields in the Yukawa interactions. Take for example the build in SM. The Yukawa terms there are

Code: Select all

LagHC =  -(Yd conj[H].d.q + Ye conj[H].e.l + Yu u.q.H);

This does only give top quark decays to bottom quark and a W. While if I modify it to

Code: Select all

LagHC =  -(Yd conj[H].q.d + Ye conj[H].e.l + Yu H.q.u);

then I'm getting all off-diagonal decays. Can you comment on that? If the order matters, shouldn't all models be written like that? Or is there some trick there?

cheers,
Wojciech

[FStaub]

Of course, the definition of the Lagrangian must be consistent with the conventions of spheno to apply flavour mixing. Therefore, there is a function which should check the order of the quarks in the Yukawa terms, and adjust the spheno output accordingly. I need to check why this seems not to work. For the moment, you can use the workaround and change the Lagrangian by hand as you did.

Cheers
Florian