Overall Normalization of the Astrophysical<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>S</mml:mi></mml:math>Factor and the Nuclear Vertex Constant for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">Be</mml:mi></mml:mrow><mml:mprescripts/><mml:mrow/><mml:mrow><mml:mn>7</mml:mn></mml:mrow><mml:mrow/><mml:mrow/></mml:mmultiscripts></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mo>(</mml:mo><mml:mi>p</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mrow><mml:mn>8</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi mathvariant="normal">B</mml:mi></mml:math>Reactions
H. XuCyclotron Institute, Texas A&M University, College Station, Texas 77843C. A. GagliardiCyclotron Institute, Texas A&M University, College Station, Texas 77843R. E. TribbleCyclotron Institute, Texas A&M University, College Station, Texas 77843A. M. MukhamedzhanovCyclotron Institute, Texas A&M University, College Station, Texas 77843N. K. TimofeyukCyclotron Institute, Texas A&M University, College Station, Texas 77843
ABI
Abstract
We point out a simple relation between the nuclear vertex constant (NVC) and the overall normalization of the astrophysical $S$ factor. Using predicted values of the NVC for the virtual decay of $^{8}\mathrm{B}\ensuremath{\rightarrow}^{7}\mathrm{Be}+p$ we find ${S}_{17}(0)\ensuremath{\approx}17.6$ eVb for $^{7}\mathrm{Be}{(p,\ensuremath{\gamma})}^{8}\mathrm{B}$ reactions, consistent with the low values extrapolated from direct capture measurements by Filippone et al. and by Vaughn et al. New possibilities, using proton transfer reactions, to measure the astrophysical $S$ factor indirectly are proposed.
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