The status of a new evaluation of astrophysical nuclear reaction rates, referred as NACRE-II, is reported. It includes 19 radiative capture and 15 transfer reactions on targets with mass numbers A < 16. This work is meant to supersede the NACRE compilation. Post-NACRE experimental data are taken into account. Extrapolations of the astrophysical S-factor to largely sub-Coulomb energies are based on the use of the potential model and of the distorted wave Born approximation (DWBA) for capture and transfer reactions, respectively. Adopted rates and their lower and upper limits are provided. Here, we illustrate with some results the general procedure followed in the construction of NACRE-II.

Light sub-GeV halo dark matter (DM) particles up-scattered by high-energy cosmic-rays (CRs) (referred to as CRDM) can be energetic and become detectable by conventional DM direct detection experiments. We perform a refined analysis on the exclusion bounds of the spin-independent DM-nucleon scattering cross section σχ p in this approach. For the exclusion lower bounds, we determine the parameter of the effective distance Deff for CRDM production using spatial-dependent CR fluxes and including the contributions from the major heavy CR nuclear species. We obtain Deff≃ 9 kpc for CRDM particles with kinetic energy above ∼ 1 GeV, which pushes the corresponding exclusion lower bounds down to σχ p∼ 4× 10-32 cm2 for DM particle mass at MeV scale and below. For the exclusion upper bounds from Earth attenuation, previous estimations neglecting the nuclear form factor leaded to typical exclusion upper bounds of σχ p∼𝒪(10-28) cm2 from the XENON1T data. Using both the analytic and numerical approaches, we show that for CRDM particles, the presence of the nuclear form factor strongly suppresses the effect of Earth attenuation. Consequently, the cross section that can be excluded by the XENON1T data can be a few orders of magnitude higher, which closes the gap in the cross sections excluded by the XENON1T experiment and that by the astrophysical measurements such that for the cosmic microwave background (CMB), galactic gas cloud cooling, and structure formation, etc..

No abstract