Late-decaying Q-ball with BBN lifetime Original Research Article

In the Affleck–Dine mechanism of baryogenesis, nontopological solitons called Q-balls can be formed. In this work we propose that such Q-balls decay during the BBN era and study the cosmological consequence of such late decays. We find that the late-decaying baryonic Q-balls with lifetime of about image can provide a new developing mechanism for the BBN through a rolling baryon-to-photon ratio η, which can naturally explain the discrepancy of the BBN prediction with the WMAP data on 7Li abundance. For the late-decaying leptonic Q-balls with lifetime of about image, we find that their decay product, gravitinos, can serve as a dark matter candidate and give an explanation for the approximate equality of dark and baryon matter densities.