Background: R-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are beta-decay half-lives of neutron rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. Purpose:To provide a table of β-decay half-lives and β-delayed neutron emission probabilities, including firstforbidden transitions, calculated within a fully self-consistent microscopic theoretical framework. The results are used in an r-process nucleosynthesis calculation to asses the sensitivity of heavy element nucleosynthesis to weak interaction reaction rates.Method: We use a fully self-consistent covariant density functional theory (CDFT) framework. The ground state of all nuclei is calculated with the relativistic Hartree-Bogoliubov (RHB) model, and excited states are obtained within the proton-neutron relativistic quasiparticle phase approximation (pn-RQRPA).Results: The β-decay half-lives, β-delayed neutron emission probabilities and the average number of emitted neutrons have been calculated for 5409 nuclei in the neutron-rich region of the nuclear chart. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced, both for even-even, odd-A and odd-odd nuclei, in particular for short-lived nuclei. Conclusions:In certain regions of the nuclear chart, first-forbidden transitions constitute a large fraction of the total decay rate and must be taken into account consistently in modern evaluations of half-lives. Both the beta-decay half-lives, and beta-delayed neutron emission probabilities have a noticeable impact on the results of heavy element nucleosynthesis models.

We perform three-flavor Boltzmann neutrino transport radiation hydrodynamics simulations covering a period of 3 s after the formation of a protoneutron star in a core-collapse supernova explosion. Our results show that a treatment of charged-current neutrino interactions in hot and dense matter as suggested by Reddy et al. [Phys. Rev. D 58, 013009 (1998)] has a strong impact on the luminosities and spectra of the emitted neutrinos. When compared with simulations that neglect mean-field effects on the neutrino opacities, we find that the luminosities of all neutrino flavors are reduced while the spectral differences between electron neutrinos and antineutrinos are increased. Their magnitude depends on the equation of state and in particular on the symmetry energy at subnuclear densities. These modifications reduce the proton-to-nucleon ratio of the outflow, increasing slightly their entropy. They are expected to have a substantial impact on nucleosynthesis in neutrino-driven winds, even though they do not result in conditions that favor an r process. Contrary to previous findings, our results show that the spectra of electron neutrinos remain substantially different from those of other (anti)neutrino flavors during the entire deleptonization phase of the protoneutron star. The obtained luminosity and spectral changes are also expected to have important consequences for neutrino flavor oscillations and neutrino detection on Earth.

Observations of metal-poor stars indicate that at least two different nucleosynthesis sites contribute to the production of r-process elements. One site is responsible for the production of light r-process elements Z ≲ 50, while the other produces the heavy r-process elements. We have analyzed recent observations of metal-poor stars selecting only stars that are enriched in light r-process elements and poor in heavy r-process elements. We find a strong correlation between the observed abundances of the N = 50 elements (Sr, Y and Zr) and Fe. It suggest that neutrino-driven winds from core-collapse supernova are the main site for the production of these elements. We explore this possibility by performing nucleosynthesis calculations based on long-term Boltzmann neutrino transport simulations. We use an equation of state that reproduces recent constrains on the nuclear symmetry energy. We predict that the early ejecta is neutron rich with Ye ∼ 0.48, it becomes proton rich around 4 s and reaches Ye = 0.586 at 9 s when our simulation stops. The nucleosynthesis in this model produces elements between Zn and Mo, including 92Mo. The elemental abundances are consistent with the observations of the metal-poor star HD 12263. For the elements between Ge and Mo, we produce mainly the neutron-deficient isotopes. This prediction can be confirmed by observations of isotopic abundances in metal-poor stars. No elements heavier than Mo (Z = 42) and no heavy r-process elements are produced in our calculations.

We show that for the active-sterile flavor mixing parameters suggested by the reactor neutrino anomaly, substantial νe-νs andνe-νs conversion occurs in regions with electron fraction of ≈ 1/3 near the core of an 8.8 M⊙ electron-capture supernova. Compared to the case without such conversion, the neutron-richness of the ejected material is enhanced to allow production of elements from Sr, Y, and Zr up to Cd in broad agreement with observations of the metal-poor star HD 122563. Active-sterile flavor conversion also strongly suppresses neutrino heating at times when it is important for the revival of the shock. Our results suggest that simulations of supernova explosion and nucleosynthesis may be used to constrain active-sterile mixing parameters in combination with neutrino experiments and cosmological considerations.

We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity including neutrino nucleus reactions for all nuclei with charge numbers Z < 76 with average neutrino energies in agreement with modern Supernova simulations. Considering progenitors with initial main sequence masses between 13 M and 30 M , we find a significant production of 11 B, 138 La, and 180 Ta by neutrino nucleosynthesis, despite the significantly reduced neutrino energies. The production of 19 F turns out to be more sensitive to the progenitor mass and structure than to the ν process. With our complete set of cross sections we have identified effects of the ν process on several stable nuclei including 33 S, 40 Ar, 41 K, 59 Co, and 113 In at the 10% level. Neutrino-induced reactions contribute to a similar extent to the production of radioactive 26 Al and increase the yield of 22 Na by 50%. Future γ ray astronomy missions may reach the precision at which the contribution from the ν process becomes relevant. We find that the production of 22 Na by the ν process could explain the Ne-E(L) component of meteoritic graphite grains. The ν process enhances the yield of 36 Cl and we point out that the resulting 36 Cl/ 35 Cl ratio is in agreement with the values infrerred for the early solar system. Our extended set of neutrino-nucleus interactions also allows us to exclude any further effects of the ν process on stable nuclei and to quantify the effects on numerous, hitherto unconsidered radioactive nuclei, e.g., 36 Cl, 72 As, 84 Rb, and 88 Y.