Explosive nucleosynthesis with fast neutrino-flavour conversion in core-collapse supernovae

Fast neutrino ( v)-flavour conversion (FFC) is a possible game-changing ingredient in core-collapse supernova (CCSN) theory. In this paper, we examine the impact of FFC on e xplosive nucleosynthesis by including the effects of FFC in conjunction with asymmetric v emission into nucleosynthetic computations in a parametric way. We find that the ejecta compositions are not appreciably affected by FFC for elements lighter than Co while the compositions are influenced by FFC for the heavier elements. We also find that the role of FFC varies depending on the asymmetric degree of v emission (m(asy)) and the degree of v-flavour mixing. The impact of FFC is not monotonic to m(asy). The change in the ejecta composition increases for higher m(asy) up to similar to 10 per cent compared with that without FFC, whereas FFC has little effect on the nucleosynthesis in very large asymmetric v emission ( (sic) 30 per cent ). Our results suggest that FFC facilitates the production of neutron-rich ejecta in most cases, although it makes the ejecta more proton-rich if anti v conversion is more vigorous than that of v. The key ingredient accounting for this trend is v absorption, whose effects on nucleosynthesis can be quantified by simple diagnostics.