The Science of LHCb

LHCb detector magnet
LHCb experiment magnets. Image © CERN
Each morning when you look in the bathroom mirror you expect to see an identical reflection of yourself. However, imagine that one morning your mirror-twin didn't pick up the toothbrush in the same way that you did.

For years, physicists believed that matter particles and their antimatter twins should behave identically, as if they were mirror images. Then, in 1964, scientists observed a certain neutral kaon decay process that defied those predictions. The phenomenon, called CP violation, has since been an area of intense study, particularly because it may provide insight into the mysterious lack of antimatter in the universe.

The international team of scientists working on the Large Hadron Collider beauty experiment—LHCb for short—study the rare phenomenon of CP violation in the decays of mesons containing b quarks. Measuring the properties of CP violation using their 21-meter-long, multilayer detector, LHCb physicists may provide new insight into the universe’s matter-antimatter imbalance.

Current particle physics theory—the Standard Model—holds that matter and antimatter existed in equal amounts just after the Big Bang and thus should have eventually annihilated into a sea of photons. The preponderance of matter in the universe today clearly demonstrates that this didn't happen, so something must have tipped the balance. 

The Standard Model cannot generate enough asymmetry between the matter and antimatter to account for the amount of matter in the universe, so LHCb scientists will study rare decays of mesons made of b (for beauty or bottom), strange and down quarks, searching for new physics that could explain the discrepancy.

LHCb physicists also search for never-before-seen particles and physics phenomena through their influence on rare decays of mesons containing b quarks. Such decays are a sensitive way to search for undiscovered high-mass particles, and may yield discoveries beyond the reach of other LHC experiments. 

An additional goal of some LHCb scientists is to use the experiment’s unique technology to study the decay products of the Higgs boson, which explains why a select group of particles have mass.