Hadron phenomenology using holographic light-front Quantum Chromodynamics

使用全息光前量子色动力学的强子现象学

• 批准号: SAPIN-2020-00051
• 负责人: Sandapen, Ruben
• 金额: $ 1.09万
• 依托单位: Acadia University
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=762577
• 关键词: Hadron; phenomenology; using; holographic; light

There are four known fundamental interactions in Nature and this proposal investigates one of the them: the strong interaction which is responsible for binding quarks together in hadrons and nucleons together in atomic nuclei. It is thus the underlying interaction for both hadronic and nuclear physics. We do have a fundamental theory for the strong interaction: Quantum Chromodynamics (QCD) and it tells us how quarks interact by exchanging gluons and also how gluons interact between themselves by exchanging other gluons. However, the equations of QCD are extremely difficult to solve exactly when the coupling between the interacting particles is strong. Experimentally, isolated quarks (or gluons) are never observed, i.e. our detectors only see hadrons. Understanding the permanent confinement of quarks and gluons inside hadrons from first principles in QCD remains to this day an open problem. Consequently, hadronic physics remain largely phenomenological. But phenomenology is what allows theory and experiment to mutually guide and reinforce each other, it is a key element to progress in science.  New insights into strongly-coupled QCD comes from conjecture, proposed by Juan Maldacena (Princeton) in the late nineties, of a mathematical equivalence between special classes of quantum theory (without gravity) in 4-dimensional spacetime and a classical (not quantum) gravity theory in a higher dimensional spacetime. The usefulness of this equivalence is due to the fact that if the quantum theory is strongly-coupled, its gravity dual is weakly-coupled. Hence, one can obtain information on the hard-to-solve quantum theory by solving instead its easy-to-solve gravity dual.  Unfortunately, the gravity dual to QCD is not known. But gravity duals to approximate versions of QCD are known and one of them is referred to as light-front holographic QCD. This research focuses on the phenomenology of light-front holographic QCD to understand hadronic structure and how the latter affects the physics of rare decays of the B meson. Such decays are extraordinarily sensitive probes to new physics beyond the Standard Model (SM).  In the recent years, a number of discrepancies between SM predictions and experimental data have been observed at the Large Hadron Collider (LHC) in Europe. A better understanding of hadronic structure will shed light on these discrepancies. At the same time, this research will serve to interpret and guide future experiments on hadronic structure from other facilities like the Jefferson Lab in the US.  This research contributes to the training of the next generation of Canadian researchers by introducing them to highly sophisticated mathematics and computational tools and giving them the opportunity to use real world data coming from particle colliders around the world. It also sustains the prominent Canadian role at the forefront of world-class research in addressing one of the most fundamental questions in contemporary particle physics.

自然界中有四种已知的基本相互作用，该提议研究了其中一种：强相互作用将强子中的夸克和原子核中的核子结合在一起，因此它是强子物理和核物理的基础相互作用。确实有一个强相互作用的基本理论：量子色动力学（QCD），它告诉我们夸克如何通过交换胶子相互作用，以及胶子如何通过交换其他胶子在它们之间相互作用。然而，当相互作用的粒子之间的耦合很强时，量子色动力学方程很难精确求解，在实验中，孤立的夸克（或胶子）永远不会被观察到，也就是说，我们的探测器只能看到强子和胶子的永久限制。量子色动力学第一原理的强子至今仍然是一个悬而未决的问题，强子物理学在很大程度上仍然是现象学的，但现象学使理论和实验能够相互指导和加强。另一方面，它是科学进步的关键要素，它来自于胡安·马尔达西纳（普林斯顿大学）在九十年代末提出的关于强耦合 QCD 的猜想，即特殊类别的量子理论（无引力）之间的数学等价性。 4 维时空和高维强时空中的经典（非量子）引力理论这种等价性的有用之处在于，如果量子理论是耦合的，则其引力对偶是。因此，我们可以通过求解容易求解的引力对偶来获得有关难以求解的量子理论的信息，不幸的是，QCD 的引力对偶尚不清楚，但 QCD 的引力对偶却是未知的。已知，其中之一被称为光前全息 QCD。这项研究的重点是光前全息 QCD 的现象学，以了解强子结构以及后者如何影响稀有物理。 B 介子的衰变是对标准模型（SM）之外的新物理学的极其敏感的探索。近年来，在大型强子对撞机（LHC）中观察到了 SM 预测和实验数据之间的许多差异。欧洲。对强子结构的更好理解将揭示这些差异。同时，这项研究将有助于解释和指导杰斐逊实验室等其他机构未来的强子结构实验。这项研究有助于培训下一代加拿大研究人员，向他们介绍高度复杂的数学和计算工具，并让他们有机会使用来自世界各地粒子对撞机的真实世界数据。加拿大在解决当代粒子物理学最基本问题之一方面处于世界级研究的前沿。