The NLO corrections to the DIS structure functions $F_2$ and $F_L$ (or equivalently the photon-target cross sections $\sigma^{ \gamma^*}_{ T}$ and $\sigma^{ \gamma^*}_{ L}$) at low $x_{ Bj}$ are obtained, as a generalization of the dipole factorization formula. For the first time, the contributions of both the $q\bar{ q}$ and the $q\bar{ q}g$ Fock states in the photon are directly calculated, using earlier results for the $q\bar{ q}$ light-front wave-functions at one loop inside a dressed virtual photon. Both the $q\bar{ q}$ and the $q\bar{ q}g$ contributions have UV divergences, which are shown to cancel each other, using conventional dimensional regularization as UV regulator. Finally, the resummation of high-energy logarithms on top of the NLO results for $\sigma^{ \gamma^*}_{ T}$ and $\sigma^{ \gamma^*}_{ L}$ is discussed.
Categories: hep-ph