1 Erratum to: Eur. Phys. J. C (2020) 80:479 https://doi.org/10.1140/epjc/s10052-020-8041-4

The original published version of the article used the symbols \(\varepsilon \) and \(\epsilon \), but only one of them was defined and should have been used. This typographical error was introduced in the proofs. The new online version corrects this issue by using \(\varepsilon \) only.

The original article has been corrected.