2,250 research outputs found

    How sensitive are various NN observables to changes in the πNN\pi NN coupling constant?

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    The deuteron, NN analyzing powers A_y, and the singlet scattering length show great sensitivity to the πNN\pi NN coupling constant gπg_\pi. While the pp A_y data favor gπ2/4π13.6g^2_\pi/4\pi\leq 13.6, the np A_y data and the deuteron quadrupole moment imply gπ2/4π14.0g^2_\pi/4\pi\geq 14.0. The two diverging values could be reconciled by the assumption of (substantial) charge-splitting of gπg_\pi. However, the established theoretical explanation of the charge-dependence of the 1S0^1S_0 scattering length (based upon pion mass splitting) is very sensitive to a difference between gπ0g_{\pi^0} and gπ±g_{\pi^\pm} and rules out any substantial charge-splitting of gπg_\pi. Thus, there are real and large discrepancies between the values for gπg_\pi extracted from different NN observables. Future work that could resolve the problems is suggested.Comment: Latex, 19 pages, 4 figures; invited talk presented at the Workshop on `Critical Points in the Determination of the Pion-Nucleon Coupling Constant', Uppsala (Sweden), June 7-8, 199

    Nuclear Forces and Nuclear Structure

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    After a historical review, I present the progress in the field of realistic NN potentials that we have seen in recent years. A new generation of very quantitative (high-quality/high-precision) NN potentials has emerged. These potentials will serve as reliable input for microscopic nuclear structure calculations and will allow for a systematic investigation of off-shell effects. The issue of three-nucleon forces is also discussed.Comment: Invited Talk presented at Nuclear Structure '98, Gatlinburg, Tennessee, August 10-15, 1998; 15 pages, 6 figures, aipproc2.sty and epsfig.st

    Recent Advances in the Theory of Nuclear Forces and its Impact on Microscopic Nuclear Structure

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    The theory of nuclear forces has made great progress since the turn of the millenium using the framework of chiral effective field theory (ChEFT). The advantage of this approach, which was originally proposed by Weinberg, is that it has a firm basis in quantum-chromodynamics and allows for quantitative calculations. Moreover, this theory generates two-nucleon forces (2NF) and many-body forces on an equal footing and provides an explanation for the empirically known fact that 2NF >> 3NF >> 4NF. I will present the recent advances in more detail and put them into historical context. In addition, I will also provide a critical evaluation of the progress made including a discussion of the limitations of the ChEFT approach.Comment: 8 pages, 2 figures, talk at EXOCT 2007, Catania, Italy, June 11-15, 200