In 2008 I was at the Open University’s Quantum Mechanics (QM) Summer School. Over coffee I confided to one of the tutors that I was pleased I would be completing the course just in time for new science from the Large Hadron Collider (LHC). This was of course before the accident with the liquid helium which set things back by a year.
The tutor rubbed his chin sagely, trying to think of any overlap between what is covered in a first course in QM and what the LHC was all about. He failed.
This note is the shortest possible explanation of what extra you need to know to understand the main professed objective of the LHC, namely to find and determine the properties of the Higgs boson ...
[Note: the text has been superceded by an improved version here.]