An approach for a Poincare covariant description of nuclear structure and of lepton scattering off nuclei is proposed within the relativistic Hamiltonian dynamics in the light-front form. Indeed a high level of accuracy is needed for a comparison with the increasingly precise present and future experimental data at high momentum transfer. Therefore, to distinguish genuine QCD effects or effects of medium modified nucleon structure functions from conventional nuclear structure effects, the commutation rules between the Poincare generators should be satisfied. For the first time in this paper a proper hadronic tensor for inclusive deep inelastic scattering of electrons off nuclei is derived in the impulse approximation in terms of the single nucleon hadronic tensor. Our approach is based : i) on a light-front spectral function for nuclei, obtained taking advantage of the successful non-relativistic knowledge of nuclear interaction, and ii) on the free current operator that, if defined in the Breit reference frame with the momentum transfer, $\bf q$, parallel to the $z$ axis, fulfills Poincare covariance and current conservation. Our results can be generalized : i) to exclusive processes or to semi-inclusive deep inelastic scattering processes; ii) to the case where the final state interaction is considered through a Glauber approximation; iii) to finite momentum transfer kinematics. As a first test, the hadronic tensor is applied to obtain the nuclear structure function F$_2^A$ and to evaluate the EMC effect for $^3He$ in the Bjorken limit. Encouraging results including only the two-body part of the light-front spectral function are presented.

中文翻译：

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EMC 效应、少核子系统和庞加莱协方差

在光前形式的相对论哈密顿动力学中，提出了一种对核结构和轻子从核上散射的庞加莱协变描述的方法。事实上，在高动量传递下，与越来越精确的当前和未来实验数据进行比较需要高水平的精度。因此，为了区分真正的 QCD 效应或中等修正核子结构函数的效应与常规核结构效应，应满足 Poincare 发生器之间的对易规则。在本文中，第一次在单核子强子张量的脉冲近似中导出了一个适当的强子张量，用于包含电子离核的深度非弹性散射。我们的方法基于：i) 基于原子核的光前光谱函数，利用核相互作用的成功非相对论知识获得，以及 ii) 在自由电流算子上，如果在 Breit 参考系中定义了动量传递 $\bf q$，平行于 $z$ 轴，满足庞加莱协方差和电流守恒。我们的结果可以推广： i) 排他过程或半包容深非弹性散射过程；ii) 通过 Glauber 近似考虑最终状态相互作用的情况；iii) 有限动量传递运动学。作为第一个测试，应用强子张量来获得核结构函数 F$_2^A$ 并评估 Bjorken 极限中 $^3He$ 的 EMC 效应。令人鼓舞的结果只包括光前光谱函数的双体部分。