Title: Non-nucleonic degrees of freedom and the spin structure of the deuteron Show Chinese title

Title: 非核子自由度与氘核的自旋结构

Abstract: Electro-disintegration of the deuteron at large $Q^2$ currently represents on of the most promising reactions which allows to probe the bound nuclear state at internal momenta comparable to the rest mass of the nucleon. Large internal momentum in this case makes non-nuncleonic states energetically more feasible and the question that we address is what are the signatures that will indicate the existence of such states in the ground state of the nuclear wave function. To probe such states we developed a light-front formalism for relativistic description of a composite pseudo-vector system in which emerging proton and neutron are observed in electro-disintegration reaction. In leading high energy approximation our calculations show the possibility of the existence of a new ``incomplete" P-state-like structure in the deuteron at extremely large internal momenta. The incompleteness of the observed P-state violates the angular condition for the momentum distribution, which can happen only if the deuteron contains non-nucleonic structures, such as $\Delta\Delta$, $N^*N$ or hidden color components. Because such states have distinctive angular momentum ($l=1$) they significantly modify the polarization properties of the deuteron wave function. As a result in addition to angular anisotropy of the LF momentum distribution of the nucleon in the deuteron one predicts strong modification of the tensor polarization asymmetry of the deuteron beyond the S- and D- wave predictions at large internal momenta in the deuteron. Show Chinese abstract

Abstract: 氘核在大$Q^2$条件下的电离解离目前代表了最有望的反应之一，这使得我们能够探测到内部动量与核子静止质量相当的束缚核态。在这种情况下，大的内部动量使非核子状态在能量上更加可行，我们要解决的问题是哪些特征将指示出这些状态存在于核波函数的基态中。 为了探测这些状态，我们开发了一种光前形式主义来描述相对论下复合伪矢量系统的性质，在这个系统中，产生的质子和中子在电离解离反应中被观测到。在高能近似下，我们的计算表明在极大的内部动量下，氘核中可能存在一种新的“不完全”的P态结构。 观察到的P态的不完整性违反了动量分布的角条件，这只能发生在氘核中含有非核子结构，如$\Delta\Delta$、$N^*N$或隐藏的颜色组分的情况下。由于这些状态具有独特的角动量（$l=1$），它们显著地改变了氘波函数的极化属性。因此，除了氘核中核子的光前沿动量分布的角各向异性外，还预测了在氘核的大内部动量下，对S波和D波预测之外的张量极化不对称性的强烈修改。