Magnetic moment; Anomalous magnetic moment; Julian Schwinger;Perturbation theory; QED; g-2; on-shell; symmetric limit; Electroweak contribution; QCD; gauge invaiant

Currently, in the scientific community of particle physics a great interest has been generated in the anomalous magnetic moment due to the disagreement that exists in the theoretical prediction and the experimental observation of the magnetic anomaly of the muon, aμ = (g − 2)/2. This discrepancy may arise from undiscovered particle effects through virtual loops, which could provide an indication of "new physics".

We study various contributions of the Standard Model to the magnetic moment at the level of at the one-loop level and we try to extend and modify it by taking the symmetric limit for the external moments of the diagram and considering mass terms of the photon and the gluon in their respective propagators.

Additionally, we analyze the anomalous chromomagnetic moment in QCD with symmetric and on-shell limits, where our main interest lies in the existence of the divergence in the non-abelian contribution in the on-shell limit.

Finally, we analyze the anomalous chromomagnetic moment for the electroweak interactions in each of the quarks, considering the symmetric configuration and the on-shell limit. All the calculations made have been done in an arbitrary (linear) covariant gauge. Only when the results are finite and gauge invariant can they be considered as physical observables.