On the neutron orbital angular momentum: Has it actually been demonstrated?

Abstract: In a Nature LETTER [1], a control of neutron angular momentum was apparently demonstrated using a neutron crystal interferometer. In the meantime, a number of highly interesting articles have been published dealing with the n-OAM and neutron interferometry, citing [1]. We show that the interpretation of [1] having detected a n-OAM is incorrect for several serious reasons and point out inconsistencies. Based only on the theory of dynamical neutron diffraction, we calculate all the interferograms and show perfect agreement with those given in [1]. There was no need to assume an additional n-OAM because no additional effect was observed that could not be explained by standard theory.