In the light of the new data on the various neutron and protonelectromagnetic form factors taken in recent years, we update thedispersion-theoretical analysis of the nucleon electromagnetic form factorsfrom the mid-nineties. The parametrization of the spectral functions includesconstraints from unitarity, perturbative QCD, and recent measurements of theneutron charge radius. We obtain a good description of most modern form factordata, with the exception of the Jefferson Lab data on G_E^p/G_M^p in thefour-momentum transfer range Q^2=3...6 GeV^2. For the magnetic radii of theproton and the neutron we find r_M^p = 0.857 fm and r_M^n = 0.879 fm, which isconsistent with the recent determinations using continued fraction expansions.
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机译：根据近年来获得的有关各种中子和质子电磁形状因数的新数据，我们更新了90年代中期对核子电磁形状因数的色散理论分析。频谱函数的参数化包括来自单一性，微扰QCD和最近对中子电荷半径的测量的约束。除了在四动量传递范围Q ^ 2 = 3 ... 6 GeV ^ 2中G_E ^ p / G_M ^ p的Jefferson Lab数据外，我们对大多数现代形状因数数据都有很好的描述。对于质子和中子的磁半径，我们发现r_M ^ p = 0.857 fm和r_M ^ n = 0.879 fm，这与最近使用连续分数展开式进行的确定是一致的。
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