Abstract

The spin response of the \(\vec{\gamma}\vec{d}\to\pi^{0}d\) reaction near threshold is investigated. Our formalism based on the impulse approximation, uses the realistic Bonn \(NN\) potential (full model) for the deuteron wave function and the unitary isobar MAID-2007 model for the elementary \(\gamma N\to\pi N\) amplitude. We present the first results for the double polarized differential and total cross sections for parallel and antiparallel helicity states, the deuteron spin asymmetry, the helicity \(E\)-asymmetry, the deuteron GDH integral, and the double spin asymmetries of the total cross section in the near-threshold region. Sensitivity of the estimated results to the \(D\)-wave effect of the deuteron wave function for a realistic \(NN\) potential is studied. We find an insignificant sensitivity of most of the estimated observables to the \(D\)-wave component. A noticeable role is obtained only in the double polarized differential cross section with antiparallel spins of photon and deuteron \(d\sigma^{A}/d\Omega_{\pi}\) close to the threshold energy at forward and backward pion angles as well as in the double spin asymmetry of the total cross section \(\sigma\tilde{T}_{20}\) at relatively large photon energies. Thus, we compare results for these two observables using various \(NN\) potential models with different \(D\)-state probabilities, and a noticeable influence is found.

中文翻译：

---

$$ \ vec {\ boldsymbol {\ gamma}} \ vec {\ boldsymbol {d}} \对\ pi ^ {0} \ boldsymbol {d} $$的自旋响应阈值附近及其对GDH的影响和规则和双极化$$ \ boldsymbol {E} $$-不对称

摘要

研究了接近阈值的\（\ vec {\ gamma} \ vec {d} \ to \ pi ^ {0} d \）的自旋响应。我们基于脉冲逼近的形式主义，对氘核波函数使用现实的波恩\（NN \）势（完整模型），对基本\（\ gamma N \ to \ pi N \）使用单一等压线MAID-2007模型。振幅。我们给出了平行和反平行螺旋状态，氘核自旋不对称性，螺旋度（E \）不对称，氘核GDH积分和总交叉的双旋不对称性的双极化微分和总横截面的第一个结果阈值附近的区域。估计结果对\（D \）的敏感性研究了氘核波函数对现实\（NN \）势的波效应。我们发现大多数估计的可观测值对\（D \）-波分量的敏感度均很小。仅在双极化微分截面中，光子和氘核的反平行自旋\（d \ sigma ^ {A} / d \ Omega _ {\ pi} \）才在接近正向和反向π角处的阈值能量附近获得明显的作用。以及在相对较大的光子能量下总横截面\（\ sigma \ tilde {T} _ {20} \）的双自旋不对称性。因此，我们使用具有不同\（D \）的各种\（NN \）势模型来比较这两个可观测值的结果状态概率，并发现明显的影响。