6 pages. Invited talk at Light Cone 2019 - QCD on the light cone: from hadrons to heavy ions, 16-20 September 2019, Ecole Polytechnique, Palaiseau, France
Light-front holography offers a successful first semiclassical approximation to hadronic spectroscopy and dynamics. We review its underlying assumptions, its remarkable predictions as well as attempts to go beyond the semiclassical approximation in order to the describe a wide range of data with a universal AdS/QCD mass scale.
We evaluate the cross section for the pion induced Drell-Yan process in two different models of the pion light-front wave function, inspired by light-front holographic approaches. We obtain the valence quark distribution functions in those models, which after QCD evolution, are consistent with the experimental data from the E-0615 experiment at Fermilab. Supplemented by the parton distribution functions of the target nuclei, we obtain the cross section consistent with the experimental data for the $π^-$ Nucleus $\rightarrow {μ^+μ^-X}$ Drell-Yan process.
We present an analytically solvable 3D light-front Hamiltonian model for hadrons that extends light-front holography by including finite mass quarks and a longitudinal confinement term. We propose that the model is suitable as an improved analytic approximation to QCD at a low resolution scale. We demonstrate that it preserves desired Lorentz symmetries and it produces improved agreement with the experimental mass spectroscopy and other properties of the light mesons. Importantly, the model also respects chiral symmetry and the Gell-Mann-Oakes-Renner relation.
I survey recent developments in hadron physics which follow from the application of superconformal quantum mechanics and light-front holography. This includes new insights into the physics of color confinement, chiral symmetry, the spectroscopy and dynamics of hadrons, as well as surprising supersymmetric relations between the masses of mesons, baryons, and tetraquarks. I also will discuss some novel features of QCD -- such as color transparency, hidden color, and asymmetric intrinsic heavy-quark phenomena. The elimination of renormalization scale ambiguities and the modification of QCD sum ru…
The Frame-Independent Spatial Coordinate $\tilde{z}$: Implications for Light-Front Wave Functions, Deep Inelastic Scattering, Light-Front Holography, and Lattice QCD Calculations
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 show the 't Hooft Equation and the light-front holographic Schrödinger Equation are complementary to each other in governing the transverse and longitudinal dynamics of colour confinement in quark-antiquark mesons. Together, they predict remarkably well the light, heavy-light and heavy-heavy meson spectroscopic data. The universal emerging hadronic scale of light-front holography, $κ\approx 0.5$ GeV, controls the transverse dynamics of confinement in all mesons. In heavy-heavy mesons, it also coincides numerically with the 't Hooft coupling which governs longitudinal confinement, thus refle…
Light-front holographic QCD provides a successful first approximation to hadron spectroscopy in the chiral limit of $(3+1)$-dim light-front QCD, where a holographic Schrödinger-like equation, with an emerging confining scale, $κ$, governs confinement in the transverse direction. In its supersymmetric formulation, light-front holography predicts that each baryon has two superpartners: a meson and a tetraquark, with their degenerate masses being generated by the same scale, $κ$. In nature, this mass degeneracy is lifted by chiral symmetry breaking and longitudinal confinement. In this paper, we …
The parton distribution functions (PDFs) of heavy mesons are evaluated from their light-front wave functions, which are obtained from a basis light-front quantization in the leading Fock sector representation. We consider the mass eigenstates from an effective Hamiltonian consisting of the confining potential adopted from light-front holography in the transverse direction, a longitudinal confinement, and a one-gluon exchange interaction with running coupling. We present the gluon and the sea quark PDFs which we generate dynamically from the QCD evolution of the valence quark distributions.
We construct spin-improved holographic light front wavefunctions for the nucleons (viewed as quark-diquark systems) and use them to successfully predict their electromagnetic Sachs form factors, their electromagnetic charge radii, as well as the axial form factor, charge and radius of the proton. The confinement scale is the universal mass scale of light-front holography, previously extracted from spectroscopic data for light hadrons. With the Dirac and Pauli form factors normalized using the quark counting rules and the measured anomalous magnetic moments respectively, the masses of the quark…
我们给出了一个概述的光阵面全息方法强耦合QCD，从而限制规范理论，量子化的光阵面，映射到一个更高的维anti de Sitter（AdS）空间。该框架是由AdS/CFT对应纳入重力背景渐近AdS空间编码的QCD的显着性能，如紫外线共形限制在AdS边界在$z \to 0$，以及修改的几何形状在大$z$红外区域描述禁闭和线性Regge行为。推导AdS/QCD运动方程有两种等价的方法：一种方法是从物理时空中的哈密顿运动方程出发，研究束缚态波函数作为组分不变质量的函数的离壳动力学。对于第一个半经典近似，其中不包括量子环和夸克质量，这导致了一个光阵面哈密顿方程，它描述了一个不变的影响变量$ζ$的强子内的部分子在相等的光阵面时间的分离方面的束缚态动力学。或者，我们可以从引力的角度出发，研究强子模在固定的有效引力背景下的传播。这两种方法在半经典近似下是等价的。这使我们能够识别AdS空间中的全息变量$z$与影响变量$ζ$。因此，光前全息术允许从AdS到物理时空的过渡振幅的精确映射。明确地介绍了强子的内部结构，其中组分的角动量起着关键作用。
We investigate the two-photon transitions $H_{c\bar c} \to γ^*γ$ of the charmonium system in light-front dynamics. The light-front wave functions were obtained from solving the effective Hamiltonian based on light-front holography and one-gluon exchange interaction within the basis light-front quantization approach. We compute the two-photon transition form factors as well as the two-photon decay widths for S- and P-wave charmonia, $η_c$ and $χ_{cJ}$ and their excitations. Without introducing any free parameters, our predictions are in good agreement with the recent experimental measurements b…
