本文提出了一种计算核子中价夸克分布的新方法，该方法基于三种主要机制产生x>0.05的价夸克谱：价夸克与剩余核子系统产生的平均场的相互作用，通过胶子交换产生的两夸克和三夸克短程相互作用.在本报告中，我们提出了该项目的第一阶段，其中我们开发了一个非微扰模型的价夸克相互作用的平均场的核子内部，以描述它们在中等x区域（0.05 < x < 0.4）的分布。在我们的方法中，短程夸克-夸克相互作用效应产生了价夸克分布的高x尾。所提出的非微扰模型是基于三个相对论性价夸克占据核子核的图像，它们之间的距离为$\le 0.5$ Fm，同时在剩余核子系统产生的平均场中相互作用.计算是基于短程三价夸克的内部相互作用与这些夸克与剩余系统的长程相互作用的a因子分解的假设。理论方法基于有效光阵面图解法，它允许我们以一致的方式引入价夸克和剩余系统波函数。这些波函数的参数由对应于粲夸克质量的Q_0处的价夸克xf_q（x）分布的峰值位置确定。我们用很少的参数对中等x区域（x < 0.4）的上下价夸克分布进行了非常合理的描述，人们期望在那里平均场动力学占主导地位。然而，该模型系统地低估了高$x$区域，其中部分子短程相关增强的贡献是预期的。
英文摘要：
We present a new approach for the calculation of the valence quark distributions in the nucleon based on the scenario in which the spectrum of the valence quarks at x>0.05 is generated through three main mechanisms: interaction of valence quarks with the mean field generated by the residual nucleon system, two and three quark short range interactions through gluon exchanges. In the current report we present the first phase of the project in which we develop a non-perturbative model for valence quark interaction in the mean field of the nucleonic interior to describe their distribution in the moderate x region (0.05 < x < 0.4). The short range quark-quark interaction effects in our approach generate the high x tail of valence quark distributions. The presented non-perturbative model is based on the picture in which three relativistic valence quarks occupy the nucleon core at distances of $\le 0.5$ Fm while interacting in the mean field generated by the residual nucleon system. The calculations are based on the assumption of the a factorization of the internal interaction of short-range three valence quarks with the long-range interaction of these quarks with the residual system. The theoretical approach is based on effective light-front diagrammatic approach which allows us to introduce the valence quark and residual system wave functions in a consistent way The parameters of these wave functions are fixed by the position of the peak of the xf_q(x) distribution of valence quarks at Q_0 corresponding to the charm-quark mass. With few parameters we achieved a very reasonable description of the up and down valence quark distributions in the moderate x region (x < 0.4), where one expects the mean field dynamics to dominate. The model, however, systematically underestimates the high $x$ region where enhanced contributions from partonic short-range correlations are expected.
Valence quark contributions for the $γ^\ast N \to N(1440)$ form factors from Light-Front holography
本文在光阵面全息的形式下研究了核子的结构和核子的第一径向激发Roper，$N(1440)$。在价夸克自由度占优势的假设下，计算了核子弹性形状因子和$γ^\ast N \to N(1440)$跃迁形状因子。与以前的研究相反，与价夸克相关的模型的裸参数是固定的大动量转移的经验数据（$Q^2$）假设的修正的三夸克图片（介子云的贡献）被抑制。然后在没有任何可调参数的情况下计算$γ^\ast N \to N(1440)$过渡形状因子。我们的估计进行了比较，从价夸克和其他模型的基础上的结果。该模型与$γ^\ast N \to N(1440)$转换形状因子的数据进行了比较，表明介子云的影响并不大，除了在$Q^2< 1.5$ GeV $^2$区域。特别是介子云对泡利形状因子的贡献很小。
We investigate the scattering of a quark jet on a high-energy heavy nucleus using the time-dependent light-front Hamiltonian approach. We simulate a real-time evolution of the quark in a strong classical color field of the relativistic nucleus, described as the Color Glass Condensate. We study the sub-eikonal effect by letting the quark jet carry realistic finite longitudinal momenta, and we find sizeable changes on the transverse coordinate distribution of the quark. We also observe the energy loss of the quark through gluon emissions in the $\ket{q}+\ket{qg}$ Fock space. This approach provid…
We have scrutinized the transverse momentum dependent quark-gluon-quark correlation function. We have utilized the light-front quark-diquark model to study the time-reversal-odd interaction-dependent twist-3 gluon distributions which we have obtained from the disintegration of the transverse momentum dependent quark-gluon-quark correlator. Specifically, we have studied the behavior of $\tilde{e}_{L}$ and $\tilde{e}_{T}$ while considering our diquark to be an axial-vector.
We explore the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the two-point and three-point functions of the pion. Including the axial-vector coupling as well as the pseudoscalar coupling in the light-front quark model, we discuss the implication of the chiral anomaly in describing the pion decay constant, the pion-photon transition form factor and the electromagnetic form factor of the pion. In constraining the model parameters, we find that the chiral anomaly plays a critical role and the analysis of $F_{πγ}(Q^2)$ in timelike …
The ladder kernel of the Bethe-Salpeter equation is amended by introducing a different flavor dependence of the dressing functions in the heavy-quark sector. Compared with earlier work this allows for the simultaneous calculation of the mass spectrum and leptonic decay constants of light pseudoscalar mesons, the $D_u$, $D_s$, $B_u$, $B_s$ and $B_c$ mesons and the heavy quarkonia $η_c$ and $η_b$ within the same framework at a physical pion mass. The corresponding Bethe-Salpeter amplitudes are projected onto the light front and we reconstruct the distribution amplitudes of the mesons in the full…
Resolving the SELEX--LHCb Double-Charm Baryon Conflict: The Impact of Intrinsic Heavy-Quark Hadroproduction and Supersymmetric Light-Front Holographic QCD
Universidade Federal Rural da Amazônia（亚马逊联邦农村大学）；Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo（克鲁塞罗苏尔大学 / 圣保罗城市大学）；Instituto Tecnológico de Aeronáutica（航空技术学院）
This is the third paper on hadronic light front wave functions (LFWFs). We derive a light front Hamiltonian from first principles using the key features of the QCD vacuum at low resolution. In the first approximation, it gives transverse oscillator and longitudinal harmonic modes and yields the correct Regge trajectories. For heavy quarkonia, we compare its spectrum to that obtained from the usual Schroedinger equation in the rest frame. We use the same approach for light quarks, and investigate the role of confinement and chiral symmetry breaking in the quark-antiquark sector. We then study s…
We investigate the structure of the light meson with one dynamical gluon from the light-front QCD Hamiltonian, determined for their constituent quark-antiquark and quark-antiquark-gluon Fock sectors, together with a three-dimensional confinement. After fitting the light meson mass spectroscopy, the light-front wave functions provide a good quality description of the pion electromagnetic form factor, and the valence quark distribution functions following QCD scale evolution.
