An experimental observation of proton decay would be a spectacular proof of Grand Unification. Currently, the best constraint on the proton lifetime for the p\to e⁺\pi ⁰ decay channel, coming from the SuperKamiokande experiment, reaches 8×10³³ years. To improve the measurement, much bigger detectors should be constructed. Moreover, a better description of the bound-nucleon states and of the propagation of the proton-decay products through nuclear matter have to be developed. In this article special attention is paid to the argon nucleus because a liquid argon detector is a promising candidate for the future large apparatus.

PACS numbers: 13.30.Ce, 14.20.Dh, 24.10.Lx, 27.40.+z