Search for resonant states in ¹⁰C and ¹¹C and their impact on the primordial ⁷Li abundance

The cosmological ⁷Li problem arises from the significant discrepancy of about a factor 3 between the predicted primordial ⁷Li abundance and the observed one. The main process for the production of ⁷Li during Big-Bang nucleosynthesis is the decay of ⁷Be. Many key nuclear reactions involved in the production and destruction of ⁷Be were investigated in attempt to explain the ⁷Li deficit but none of them led to successful conclusions. However, some authors suggested recently the possibility that the destruction of ⁷Be by ³He and ⁴He may reconcile the predictions and observations if missing resonant states in the compound nuclei ¹⁰C and ¹¹C exist. Hence, a search of these missing resonant states in ¹⁰C and ¹¹C was investigated at the Orsay Tandem-Alto facility through ¹⁰B(³He,t)¹⁰C and 11B(³He,t)¹¹C charge-exchange reactions respectively. After a short overview of the cosmological ⁷Li problem from a nuclear physics point of view, a description of the Orsay experiment will be given as well as the obtained results and their impact on the ⁷Li problem. (paper)