# What We Know So Far: An Introduction to the Standard Model

February 17, 2017

Kevin Grizzard, Department of Medical Physics, Virginia Commonwealth University

The modern understanding of nature at its most fundamental level is built on two foundations. One is general relativity, which describes gravity and the large scale structure of the universe. The other is commonly known as the Standard Model of particle physics ("the SM"), which incorporates quantum mechanics and special relativity in a description of the known elementary particles and their interactions via the electromagnetic force, the strong nuclear force, and the weak nuclear force. It also describes how elementary particles acquire mass via the Higgs mechanism, and the detection of a Higgs boson at the Large Hadron Collider in 2012, some fifty years after its proposal, was one of the greatest confirmations of a theoretical prediction in history. I will give an overview of the SM, noting some of its motivations and successes while emphasizing its essential conceptual features (e.g., the least-action principle; symmetries including Poincare invariance and gauge symmetry; the Higgs mechanism).