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arXiv 1704.04562hep-ph
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$γp \to K^{*+} Λ$中的核子共振

Nucleon resonances in $γp \to K^{*+} Λ$

A. C. Wang, W. L. Wang, F. Huang, H. Haberzettl, K. Nakayama

备注：
19 pages, 14 figures
发表信息：
Phys. Rev. C 96, 035206 (2017)
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摘要：

基于一种有效的拉格朗日方法，在树级近似的基础上，分析了由CLAS合作在托马斯杰斐逊国家加速器设施报道的反应$γp \to K^{*+}Λ$的高精度截面数据。除了$t$通道的$K$、$κ$、$K^*$交换、$s$通道的核子（$N$）交换、$u$通道的$Λ$、$Σ$、$Σ^*(1385)$交换和广义接触项外，在构造反应振幅时还考虑了来自$s$通道中的近阈值核子共振的贡献.结果发现，为了达到一个令人满意的描述的微分截面数据，至少有两个核子共振应包括在内。通过包括$N(2060){5/2}^-$共振（负责$K^*Λ$阈值附近的角分布形状）以及$N(2000){5/2}^+$、$N(2040){3/2}^+$、$N(2100){1/2}^+$、$N(2120){3/2}^-$和$N(2190){7/2}^-$共振之一，可以很好地描述横截面数据，拟合的共振质量和宽度与粒子数据组主张的一致。由此产生的预测的光束，目标，反冲不对称性被发现是完全不同的各种拟合，表明自旋观测数据的必要性$γp \to K^{*+}Λ$，以进一步钉在这个反应中的共振内容和相关参数。

英文摘要：

The high-precision cross-section data for the reaction $γp \to K^{*+}Λ$ reported by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility have been analyzed based on an effective Lagrangian approach in the tree-level approximation. Apart from the $t$-channel $K$, $κ$, $K^*$ exchanges, the $s$-channel nucleon ($N$) exchange, the $u$-channel $Λ$, $Σ$, $Σ^*(1385)$ exchanges, and the generalized contact term, the contributions from the near-threshold nucleon resonances in the $s$-channel are also taken into account in constructing the reaction amplitude. It is found that, to achieve a satisfactory description of the differential cross section data, at least two nucleon resonances should be included. By including the $N(2060){5/2}^-$ resonance, which is responsible for the shape of the angular distribution near the $K^*Λ$ threshold, and one of the $N(2000){5/2}^+$, $N(2040){3/2}^+$, $N(2100){1/2}^+$, $N(2120){3/2}^-$ and $N(2190){7/2}^-$ resonances, one can describe the cross-section data quite well, with the fitted resonance masses and widths compatible with those advocated by the Particle Data Group. The resulted predictions of the beam, target, and recoil asymmetries are found to be quite different from various fits, indicating the necessity of the spin observable data for $γp \to K^{*+}Λ$ to further pin down the resonance contents and associated parameters in this reaction.

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