Light gauge boson (dark photon) for a model with new U1

[amaliab2]

Hello,

I am trying to obtain a Model that has a new U1 symmetry and the new physical gauge boson is very light ( less than a GeV) such as a dark photon. I have tried with some of the models in the U1Extensions and with the model created by A. Vicente, F. Staub and D. Aristizabal. In neither of these models I managed to get a mass for the dark photon that is much lower than the Z boson. As was suggested in a previous post on this forum, I have commented in the file LoopMasses generated for SPheno the following lines:
! Set pole masses
!MVWm = mW
!MVWm2 = mW2
!MVZ = mZ
!MVZ2 = mZ2
!MFe(1:3) = mf_l
!MFe2(1:3) = mf_l**2
!MFu(1:3) = mf_u
!MFu2(1:3) = mf_u**2
!MFd(1:3) = mf_d
!MFd2(1:3) = mf_d**2

yet the outcome is the same.
The parameters I am using on the LesHouches.in. file should lead to a low dark photon mass according to the mass matrix calculation in Mathematica.
Do you know how can I change this?
Thank you very much.
Amalia B

[charlie]

This may be too late, but make sure you re-compiled the binary after commenting the lines