On the infrared sensitivity of the longitudinal cross section in $e^{+}{e}^{-}$ annihilation

M. Beneke, V. M. Braun, L. Magnea

We have calculated the contributions proportional to ${\beta }_0^n{\alpha }_s^{n+1}$ to the longitudinal fragmentation function in $e^{+}{e}^{-}$ annihilation to all orders of perturbation theory. We u…