  Reaching next-to-leading order accuracy in perturbative calculations of
particle production in QCD at high energy is essential for reliable
phenomenological applications. In recent years, the Color Glass Condensate
effective theory (the natural framework for such calculations) has indeed been
promoted to NLO accuracy. However, the first NLO calculation of
single-inclusive hadron production met with an unexpected difficulty: the
cross-section suddenly turns negative at transverse momenta of the order of a
few GeV, in a range where perturbation theory is expected to be reliable. We
summarize recent efforts to understand and solve this issue, as well as to
develop a running coupling scheme that can be used to consistently describe
various processes in this formalism.
