Our current understanding of matter and forces at the subatomic scale, as embodied in the Standard Model of particle physics, is widely considered incomplete. Its most famous missing ingredient is the Higgs Boson, thought to endow all particles with mass, but there are strong indications that other pieces of the theoretical jigsaw puzzle are missing too.
One of these concerns "dark matter", the mysterious substance thought to make up more than a fifth of the universe. Postulated to account for gravitational effects that cannot be explained by the amount of visible matter alone, dark matter could be made up of exotic new particles that are not described by the Standard Model. Fortunately, there is a good chance that such particles – and the Higgs – will be created in the high-energy collisions between protons at the Large Hadron Collider (LHC).
There are two approaches to discovering such new physics. The first is to try and observe the new particles directly by detecting their decay products, which will be the goal of the two giant "general-purpose" LHC experiments ATLAS and CMS. The alternative approach is to make precision measurements of parameters that are predicted within the Standard Model and to look for deviations that could be due to as-yet-undetected particles. This is the goal of the LHCb (LHC beauty) experiment, which is dedicated to the precision study of particles that contain the bottom or beauty quark.
In the October issue of Physics World, Roger Forty discusses how the measurements could solve one of the most profound mysteries in physics: why the world is made up almost entirely of matter.