% miko:type: atomic
% miko:title: QCD and Asymptotic Freedom
% miko:summary: The strong interaction becomes weaker at short distances and stronger at long distances.
% miko:tags: particle
% miko:difficulty: undergrad
% miko:related: complete-particle-physics, standard-model, feynman-diagrams
% miko:keywords: QCD, running coupling, color

\documentclass{article}
\usepackage{amsmath}
\title{QCD and Asymptotic Freedom}
\begin{document}
\maketitle

\section{QCD}

Quantum chromodynamics is the $SU(3)_C$ gauge theory of the strong interaction.
Quarks carry color charge and gluons mediate the force.

\section{Running Coupling}

The strong coupling depends on the energy scale. At high energy or short
distance, it becomes smaller. This is asymptotic freedom.

\section{Confinement}

At low energy, the coupling grows. Isolated quarks are not observed as free
particles; physical states are color-neutral hadrons.

\end{document}
