  Halo nuclei are exotic nuclei which exhibit a strongly clusterised structure:
they can be seen as one or two valence nucleons loosely bound to a core. Being
observed at the ridge of the valley of stability, halo nuclei are studied
mostly through reactions. In this contribution the reaction models most
commonly used to analyse experimental data are reviewed and compared to one
another. A reaction observable built on the ratio of two angular distributions
is then presented. This ratio enables removing most of the sensitivity to the
reaction mechanism, which emphasises the effects of nuclear structure on the
reaction.
