Pairing correlations. I. Description of odd nuclei in mean-field theories

International audienceIn order to extract informations on pairing correlations in nu-clei from experimental masses, the different contributions to odd-even mass differences are investigated within the Skyrme HFB method. In 1 this first paper, the description of odd nuclei within HFB is discussed since it is the key point for the understanding of the above mentioned contributions. To go from an even nucleus to an odd one, the advantage of a two steps process is demonstrated and its physical content is discussed. New results concerning time-reversal symmetry breaking in odd-nuclei are also reported