A different interpretation of "Measuring propagation speed of Coulomb fields" by R. de Sangro, G. Finocchiaro, P. Patteri, M. Piccolo, G. Pizzella

We claim that the anti-relativistic statement in de Sangro et al., Eur. Phys. J. C 75, 137 (2015) that the Coulomb field of a moving charge propagates rigidly with it, cannot as a matter of fact be inferred from the measurements reported in that reference. Registered is not the passing of the Coulomb disk, but the acceleration-dependent part of the Lienard-Wiechert field.Comment: Comment on a work published in Eur. Phys. J. C, 3 page

Note on "Finite Field-Energy and Interparticle Potential in Logarithmic Electrodynamics"

We propose an identification of the free parameter in the model of nonlinear electrodynamics proposed in P. Gaete and J. Helayel-Neto, Eur. Phys. J. C 74, 2816 (2014) by equating the second term in the power expansion of its Lagrangian with that in the expansion of the Heiseberg-Euler Lagrangian. The resulting value of the field-energy of a point-like charge makes 0.988 of the electron mass, if the charge is that of the electron.Comment: 2 pages, a comment on a published work, to be submitted to Eur. Phys. J.

Nonlinear magnetic response of the magnetized vacuum to applied electric field

We find first nonlinear correction to the field, produced by a static charge at rest in a background constant magnetic field. It is quadratic in the charge and purely magnetic. The third-rank polarization tensor - the nonlinear response function - is written within the local approximation of the effective action in an otherwise model- and approximation-independent way within any P-invariant nonlinear electrodynamics, QED included.Comment: 11 pages without figures or tables. Numerical coefficients and some signs in Version I corrected, three new references and two equations adde