Speaker
Summary
The LHC is a proton-proton collider, thus in its use as a research tool it is essential to have the best possible theoretical understanding of QCD, the theory of the strong interactions within the Standard Model. Because QCD is asymptotically free at high energy, any cross section can be expressed as a series expansion in $\alpha_s$. For most processes, it suffices to evaluate the series at next-to-leading (NLO) accuracy, which has several desirable features, but in some cases might be not accurate enough. For instance, in the extraction of $\alpha_s$ from the data, where in order to avoid that the main source of uncertainty be due to the NLO evaluation of some production rates, like the event shapes of jet production in e+e- collisions, only observables evaluated at NNLO accuracy are considered. In this talk we report on the state of the art on the calculation of cross
section at next-to-next-to-leading (NNLO) accuracy, with particular emphasis on the process $e^+e^-\rightarrow 3jets$.
