Nucleon Capture Cross Sections
Calculated from ab initio Wave Functions

Christian Forssen
Lawrence Livermore National Laboratory

I will discuss present attempts to employ high-precision nuclear  
structure information, from a microscopic many-body model, in nuclear  
reaction calculations. The ultimate goal is to develop a fundamental  
theory for light-ion fusion reactions based on realistic inter-nucleon  
forces. The foundation of our approach is the ab initio no-core shell  
model (NCSM), which is a well-established theoretical framework aimed  
at an exact description of nuclear structure starting from  
high-precision interactions between the nucleons. After a short  
introduction to the nuclear many-body problem, and the NCSM in  
particular, I will describe how we can extract translationally  
invariant cluster form factors (overlap functions) from A-body wave  
functions in the harmonic-oscillator basis space, and subsequently use  
them in cross section calculations. Examples will be given for a few  
capture reactions that are of interest for nuclear astrophysics.