THE FATE OF LI AND BE IN STARS AND IN THE LABORATORY

We connect the observed under-abundances of Li and Be in dwarfs, with recent results on nuclear cross sections at low energies: for collisio ns of protons with atomic or molecular targets, the measured cross sec tions seem too high with respect to extrapolations for bare nuclei. Ph enomenologically, these anomalous nuclear interactions can be describe d in terms of an effective screening potential U-lab in the range of f ew hundred eV: in the presence of the electron cloud, nuclei become mo re transparent to each other as if the effective collision energy is a umented by U-lab. This implies that fusion cross sections are enlarged and at the same time elastic cross sections are lowered. If something similar occurs in stellar plasma, the nuclear burning temperatures ar e lowered, whereas diffusion processes are enhanced. We find that the observed Li and Be abundances in the Hyades and in the Sun can be repr oduced for effective screening potentials of the plasma in the range o f 600-700 eV, close to that found by experiments in the laboratory.