https://doi.org/10.1140/epjc/s10052-021-09093-w
Regular Article – Theoretical Physics
Contributions to 
(
) couplings from CP violating flavor changing couplings
1
Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, C.P. 72570, Puebla, Pue, Mexico
2
Ingeniería en Mecatrónica, Universidad Politécnica de Puebla, Tercer Carril del Ejido Serrano s/n, San Mateo Cuanalá, Juan C. Bonilla, Puebla, Puebla, Mexico
Received:
2
February
2021
Accepted:
30
March
2021
Published online:
10
April
2021
The one-loop contributions to the trilinear neutral gauge boson couplings (), parametrized in terms of one CP-conserving 
and one CP-violating 
form factors, are calculated in models with CP-violating flavor changing neutral current couplings mediated by the Z gauge boson and an extra neutral gauge boson 
. Analytical results are presented in terms of Passarino-Veltman scalar functions. Constraints on the vector and axial couplings of the Z gauge boson 
and 
are obtained from the current experimental data on the 
decays. It is found that in the case of the 
vertex the only non-vanishing form factor is 
, which can be of the order of 
, whereas for the 
vertex both form factors 
and 
are non-vanishing and can be of the order of 
and 
, respectively. Our estimates for and are smaller than those predicted by the standard model, where is absent up to the one loop level. We also estimate the 
form factors arising from both diagonal and non-diagonal couplings within a few extension models. It is found that in the diagonal case 
is the only non-vanishing form factor and its real and imaginary parts can be of the order of 
–
and 
–, respectively, with the dominant contributions arising from the light quarks and leptons. In the non-diagonal case 
can be of the order of 
, whereas 
can reach values as large as 
–
, with the largest contributions arising from the 
couplings.
© The Author(s) 2021
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