标题： $πNN$和$πNΔ$从$πN$散射的微观模型中确定的形式因子 显示英文标题

标题： $πNN$ and $πNΔ$ formfactors determined from a microscopic model for $πN$ scattering

摘要： 我们从$P_{11}$与$P_{33}$的$\pi N$散射的分波中，通过用$\pi N$非极点贡献对相应的裸顶点进行修饰来确定$\pi NN$和$\pi N\Delta$形因子。 基础模型基于介子交换，并包括核子和delta-轴子极点项以及交叉极点项，同时还包括在$\pi\pi$-交换的$J^P=0^+$($\sigma$) 和$1^-$($\rho$) 通道中的相关性。 结果对于$\pi NN$和$\pi N\Delta$非常相似，可以大致用截止质量为$>$500 MeV 的单极子来参数化，由于模型依赖性有些变化。 因此，形式因子比之前对$\pi NN$情况由 Saito 和 Afnan 使用相同方法但不同的$\pi N$相互作用模型得出的结果要硬得多。 显示英文摘要

摘要： We determine the $\pi NN$ and $\pi N\Delta$ formfactors from the $P_{11}$ resp. $P_{33}$ partial wave of $\pi N$ scattering by dressing corresponding bare vertices with the help of $\pi N$ non--pole contributions. The underlying model is based on meson exchange, and involves nucleon and delta--isobar pole and crossed--pole terms together with correlated $\pi\pi$--exchange in the $J^P=0^+$ ($\sigma$) and $1^-$ ($\rho$) channel. The results are very similar for $\pi NN$ and $\pi N\Delta$ and can be roughly parametrized by a monopole with cutoff mass $>$ 500 MeV, with some variation due to model dependencies. Thus the formfactors are much less soft than derived before for the $\pi NN$ case by Saito and Afnan using the same procedure but different $\pi N$ interaction models.