1 Erratum to: Eur. Phys. J. C (2017) 77(6):376 https://doi.org/10.1140/epjc/s10052-017-4930-6

This erratum concerns the correction of some typographic errors appearing in the second and third sections of the article. The errors do not affect any of the results presented.

  • The definitions of operators \(Q_5\) and \(\mathcal {Q}_5\) in Eq. (2.1) should read

    $$\begin{aligned} Q_5^\pm = -2\mathcal {O}^\pm _\mathrm{TT}, \quad \mathcal {Q}_5^\pm = -2\mathcal {O}^\pm _{\mathrm{T}{\tilde{\mathrm{T}}}}. \end{aligned}$$

  • To simplify the notation, from Eq. (2.7) on, the superscript ± is omitted.

  • In Eqs. (2.8), (2.9), (2.18), (2.21), (2.26) and (2.36) the partial derivative should be replaced with a total derivative.

  • In Eq. (2.16) the − sign should be replaced with a \(+\) sign.

  • In Eq. (3.15) \(G^\pm _{k;s}(x_0)\) should be replaced with \(G^\pm _{k;s}(T-x_0)\).

  • From Eq. (3.25) until the end of Section 3, Z should be replaced with \(\mathcal {Z}\).

  • Equation (3.25) should read \({\mathcal {Z}}_{1;s,\alpha }^{\pm }{\mathcal A}_{1;s,\alpha }^{\pm }=\left. {\mathcal A}_{1;s,\alpha }^{\pm }\right| _{g_0^2=0}\).

We thank A. Vladikas for his careful reading of this manuscript.