Probing the physics of confinement: the GlueX Project

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（SM）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“减弱”相互作用进行分析计算。然而，当夸克结合在一起形成我们所知道的物质时，它们的相互作用是如此强烈，以至于它们不能被分离，也不能作为单个的“自由”夸克存在。这是一个实验事实，它给SM强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, that have strengthened our conviction that the basic model, known as the Standard Model (SM), is essentially a valid - but not necessarily complete - description of the subatomic world. 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 matter as we know it, their interactions are so strong that they cannot be separated and cannot exist as individual "free" quarks. This is an experimental fact that imposes and additional aspect to the SM, that of "quark confinement". Its exact nature remains one of the outstanding problems in physics.