Dear Florian,

do you have a reference for the STU formulas implemented in SPheno?
If I compare the implementation to the formulas given in the PDG review 10. (Electroweak Model and Constraints on New Physics), Eq. 10.66, the implementation for T has the same sign, while the one for S and U has the opposite one.

As far as I know, the in the PDG the self energies Pi are defined with a minus sign compared to the SARAH/SPheno convention, so the expressions for S and U actually agree, while the one for T has a minus sign extra.
This is also supported by the fact that if I try to insert the SPheno expressions into the S,T,U contributions to the W mass
(Eq. 3.14 of Peskin & Takeuchi, Phys. Rev. D 46, 381 ) Pi_ZZ(0) should for example drop out.
This also seems to be backed when comparing the T parameter and the delta rho implementations which should match if both follow the standard definitions.

Cheers,
Philip

Hi Philipp,

thanks, I was actually taking the PDG and forgot about the difference conventions. It's just a bit surprising because I compared with GMCalc and found agreement...

Cheers,
Florian