The α + d → 6 Li + γ radiative capture is studied in order to predict the 6 Li primordial abundance. Within a two-body framework, the α particle and the deuteron are considered the structureless constituents of 6 Li. Five α + d potentials are used to solve the two-body problem: four of them are taken from the literature, only one having also a tensor component. A fifth model is here constructed in order to reproduce, besides the 6 Li static properties as binding energy, magnetic dipole, and electric quadrupole moments, also the S-state asymptotic normalization coefficient (ANC). The two-body bound and scattering problem is solved with different techniques, in order to minimize the numerical uncertainty of the present results. The long-wavelength approximation is used, and therefore only the electric dipole and quadrupole operators are retained. The astrophysical S factor is found to be significantly sensitive to the ANC, but in all the cases in good agreement with the available experimental data. The theoretical uncertainty has been estimated of the order of few percent when the potentials which reproduce the ANC are considered, but increases up to 20% when all five potential models are retained. The effect of this S-factor prediction on the 6 Li primordial abundance is studied, using the public code PArthENoPE. For the five models considered here we find 6 Li/H = (0.9-1.8) × 10 −14 , with the baryon density parameter in the 3-σ range of Planck 2015 analysis, b h 2 = 0.022 26 ± 0.000 23.

Theν e + 2 H → e + + n + n, ν e + + n + n + p reactions (l = e, µ, τ ) are studied consistently in momentum space for (anti)neutrino energies up to 300 MeV. For most of these processes we provide predictions for the total cross sections and in the case of the (anti)neutrino-3 He and (anti)neutrino-3 H inelastic scattering we compute examples of essential response functions, using the AV18 nucleon-nucleon potential and a singlenucleon weak current operator. For the reactions with the deuteron we study relativistic effects in the final state kinematics and compare two-nucleon scattering states obtained in momentum and coordinate spaces. Our results from momentum space are compared with the theoretical predictions by G. Shen et al., Phys. Rev. C86, 035503 (2012). The observed disagreement can be attributed to the differences in kinematics and in the weak current operator.

Response functions, differential cross sections and total cross sections for several (anti)neutrino induced reactions on 2 H, 3 He and 3 H are calculated in momentum space for (anti)neutrino energies up to 160 MeV, using the AV18 nucleon-nucleon potential and a single-nucleon weak current operator. This work is a continuation of our investigations presented in J. Golak et al. [Phys. Rev. C98, 015501 (2018)].