  Accurate 7Li(d,n)24He thermonuclear reaction rates are crucial for precise
prediction of the primordial abundances of Lithium and Beryllium and to probe
the mysteries beyond fundamental physics and the standard cosmological model.
However, uncertainties still exist in current reaction rates of 7Li(d,n)24He
widely used in Big Bang Nucleosynthesis (BBN) simulations. In this work, we
reevaluate the 7Li(d,n)24He reaction rate using the latest data on the three
near-threshold 9Be excited states from experimental measurements. We present
for the first time uncertainties that are directly constrained by experiments.
Additionally, we take into account for the first time the contribution from the
subthreshold resonance at 16.671 MeV of 9Be. We obtain a 7Li(d,n)24He rate that
is overall smaller than the previous estimation by about a factor of 60 at the
typical temperature of the onset of primordial nucleosynthesis. We implemented
our new rate in BBN nucleosynthesis calculations, and we show that the new
rates have a very limited impact on the final light element abundances in
uniform density models. Typical abundance variations are in the order of
0.002%. For nonuniform density BBN models, the predicted 7Li production can be
increased by 10% and the primordial production of light nuclides with mass
number A>7 can be increased by about 40%. Our results confirm that the
cosmological lithium problem remains a long-standing unresolved puzzle from the
standpoint of nuclear physics.
