Primordial or big bang nucleosynthesis ( BBN ) is one of the three historical strong evidences for the big bang model .
Standard BBN is now a parameter free theory , since the baryonic density of the Universe has been deduced with an unprecedented precision from observations of the anisotropies of the cosmic microwave background ( CMB ) radiation .
There is a good agreement between the primordial abundances of ^ { 4 } He , D , ^ { 3 } He and ^ { 7 } Li deduced from observations and from primordial nucleosynthesis calculations .
However , the ^ { 7 } { Li } calculated abundance is significantly higher than the one deduced from spectroscopic observations and remains an open problem .
In addition , recent deuterium observations have drastically reduced the uncertainty on D/H , to reach a value of 1.6 % .
It needs to be matched by BBN predictions whose precision is now limited by thermonuclear reaction rate uncertainties .
This is especially important as many attempts to reconcile Li observations with models lead to an increased D prediction .
Here , we re-evaluates the d ( p , \gamma ) ^ { 3 } He , d ( d , n ) ^ { 3 } He and d ( d , p ) ^ { 3 } H reaction rates that govern deuterium destruction , incorporating new experimental data and carefully accounting for systematic uncertainties .
Contrary to previous evaluations , we use theoretical ab initio models for the energy dependence of the S –factors .
As a result , these rates increase at BBN temperatures , leading to a reduced value of D/H = ( 2.45 \pm 0.10 ) \times 10 ^ { -5 } ( 2 \sigma ) , in agreement with observations .