Characterizing the efficiency of magnetic braking: ALMA observations to probe the physicochemical co

How the angular momentum of parent cores is transfered to the central regions and redistributed during the star formation process is not well constrained observationally. The presence of strong magnetic fields in dense cores appears as a solution for the redistribution of angular momentum through magnetic braking. B335 is a young protostar which has been shown to present no resolvable disk, organized magnetic fields, and slowing down of its envelope rotation: hence it is considered as an ideal candidate to study magnetic braking efficiency and the possible physical processes allowing the field to diffuse towards the central, high density parts. The huge resolving power of ALMA allows to measure these constrains with an unprecedent precision and therefore to have a better understanding of the processes that allow star and solar system formation. ALMA high angular resolution observations of the young Class 0 protostar B335, in several bands were obtained, probing the emission of different molecular lines tracing neutrals and ions at all envelope scale, from 50-5000 au. Preliminary results regarding the degree of ionization in the B335 envelope, the coupling of the infalling matter to the local magnetic fields, and estimates of the ambipolar diffusion scale will be presented. It will be shown how the data will allow to calculate in a precise way the strength of the magnetic field in the B335 envelope, as well as the first attempts at using these observational constraints as inputs to MHD simulations and ultimately produce better description of the physical processes at work in this young protostar