论文标题
$γd\至π^0ηD$反应的理论研究
Theoretical study of the $γd \to π^0ηd$ reaction
论文作者
论文摘要
我们已经对$γd\至π^0ηd$反应进行了理论研究，该反应是从$γn\ toπ^0ηn$反应开始的，该模型在低能时重现了横截面和极化可观察到$γn\ to $γn\toΔ（1700）\至δ（1700）\ to $ qurovess。对于Deuteron中的相干反应，我们考虑了脉冲近似以及与亲核的脱落和$η$相比与产生它们的核子的$η$。我们发现这种第二种机制非常重要，因为它有助于在两个核子之间共享反应的较大动量转移。对$γd\toπ^0ηD$反应的其他贡献，涉及$γn\至π^\pmπ^0 n^\ prime $过程，然后还包括了$π^\ pm $与另一个核子的撤销，以给出$η$和一个核子。我们发现了一种自然的解释，与模型的动力学相关，与相比计算相比，$η-D $质量分布向较低不变质量的转移以及$π^0-d $质量分布到较大的不变质量。我们还研究了与该过程中涉及的Deuteron波函数的较大动量以及模型中存在的耦合有关的理论不确定性。在实验角度分布中发现了惊人的差异，可能需要进一步进行理论研究。
We have done a theoretical study of the $γd \to π^0 ηd$ reaction starting with a realistic model for the $γN \to π^0 ηN$ reaction that reproduces cross sections and polarization observables at low energies and involves the $γN \to Δ(1700)\to ηΔ(1232) \to ηπ^0 N$ process. For the coherent reaction in the deuteron we considered the impulse approximation together with the rescattering of the pions and the $η$ on a different nucleon than the one where they are produced. We found this second mechanism very important since it helps share between two nucleons the otherwise large momentum transfer of the reaction. Other contributions to the $γd\toπ^0ηd$ reaction, involving the $γN\to π^\pmπ^0 N^\prime$ process, followed by the rescattering of the $π^\pm$ with another nucleon to give $η$ and a nucleon, have also been included. We find a natural explanation, tied to the dynamics of our model, for the shift of the $η-d$ mass distribution to lower invariant masses, and of the $π^0-d$ mass distribution to larger invariant masses, compared to a phase space calculation. We also study theoretical uncertainties related to the large momenta of the deuteron wave function involved in the process as well as to the couplings present in the model. Striking differences are found with the experimental angular distribution and further theoretical investigations might be necessary.
