Ab initio nuclear theory for applications in astrophysics and tests of fundamental symmetries

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Atomic nuclei are quantum many-body systems made by protons and neutrons interacting with forces that originate from the fundamental theory of Quantum Chromo-Dynamics. The exact treatment of nuclei starting from the constituent nucleons and the inter-nucleon interactions among them has been a long-standing goal in nuclear physics. The goal of this project is to develop a predictive ab initio theory of nuclear structure and nuclear reactions for light and medium mass nuclei. Such a theory is needed to understand nuclear reactions important for astrophysics, to calculate electroweak reactions and decays of nuclei, to provide nuclear physics input for tests fundamental symmetries and for search for physics beyond the standard model, to understand fusion reactions important for the future energy generation, and to interpret the structure of exotic nuclei investigated at facilities like ISAC/ARIEL at TRIUMF. At the same time, it provides a feedback on the quality of inter-nucleon interactions used as input to these calculations and ultimately helps to improve our knowledge of the nucleon-nucleon interaction, and in particular of the still-not-completely-understood three-nucleon interaction. In this proposal, we combine an ab initio nuclear structure approach capable to describe bound states of nuclei with a microscopic cluster method developed to describe reactions of nuclear clusters. The resulting method provides a unified description of both bound and unbound nuclear states starting from inter-nucleon interactions among protons and neutrons. We will apply this method for example to improve our understanding of reactions with 8Be as the composite system, e.g., the transfer 7Li(p,n)7Be and electromagnetic captures 7Li(p,?)8Be and 7Li(p,e+e--)8Be relevant for Big Bang nucleosynthesis and the 7Li puzzle as well as for the recently claimed observation of a 17 MeV fifth--force boson. We will investigate 10C?10B and 14O?14N beta decays relevant for probing of the CKM matrix unitarity, an important test of the standard model. We will also focus on the 6He?6Li transition including predictions of the ß--energy spectrum investigated experimentally at present, which is one of the precision tests looking for evidence of interactions beyond the standard model. As experiments are proposed to measure nuclear spin -dependent parity- violating effects in polyatomic molecules, we will continue our calculations of anapole moments of the involved nuclei and focus on contributions from different terms of parity -violating nucleon-nucleon interaction. A similar sensitivity study will be performed in calculations of nuclear electric dipole moments. Finally, a long-term goal of this project is the calculation of reactions important for stellar synthesis of 12C and 16O. This is now within reach as the a--a scattering capability has been developed. The complexity of theoretical understanding of these reactions requires exa-scale computing.