Mapping the Spectrum of Light Quark Mesons and Gluonic Excitations with Linearly Polarized Photons

亚原子物理学试图在最基本的层面上理解自然及其所有规律，直至其基本成分及其相互作用。在过去的几十年里，利用加速器和天体物理观测，我们取得了巨大的进步，这加强了我们的信念，即被称为标准模型的基本模型，本质上是对亚原子世界的有效描述，但不一定是完整的。它的成功基本上是基于“渐近自由”的概念，该概念规定，当夸克（最基本的粒子）的分离距离很小时（例如在高能碰撞中），它们的行为就像自由粒子一样，这样就可以对它们的弱相互作用进行分析计算。然而，当夸克结合在一起形成普通物质时，它们的相互作用是如此强烈，以至于它们不能分离，也不能作为单个的自由夸克存在。这是一个实验事实，它给标准模型增加了一个额外的方面，即“夸克约束”。它的确切性质仍然是物理学中突出的问题之一。

Subatomic physics seeks to understand nature - and all its laws - at the most fundamental level, down to its elementary constituents and their interactions. Tremendous strides have been made in the last several decades, using accelerators and astrophysical observations, which have strengthened our conviction that the basic model, known as the Standard Model, is essentially a valid description of the subatomic world but not necessarily a complete one. Its success is based fundamentally on the concept of “asymptotic freedom,” which stipulates that the quarks, the most elemental particles, behave as free particles when their separation distance is small (such as in high energy collisions) so that analytical calculations of their weakened interactions can be made. However, when the quarks are bound together to form ordinary matter their interactions are so strong that they cannot be separated and cannot exist as individual free quarks. This is an experimental fact that imposes an additional aspect to the Standard Model, that of “quark confinement.” Its exact nature remains one of the outstanding problems in physics.