1 Erratum to: Eur. Phys. J. C https://doi.org/10.1140/epjc/s10052-015-3580-9

In Ref. [1], the following corrections should be applied:

Eq. (10): the last bracket in the third line should be removed.

Eq. (27): the factor \(\nu ^2\) should be replaced by \(\nu ^2+Q^2\).

Eq. (56): \(j_\nu (y)\) should be replaced by \(j_\mu (y)\).

Eq. (57): the factor m in the denominator should be omitted.

Eq. (63): \(dQ^2Q^2\) should be replaced by \(dQ^2\).

Eq. (B.46): the minus sign on the r.h.s. of the second line should be removed.