International Physics Masterclasses

Research at the LHC

The LHC is the biggest and most powerful particle accelerator in the world. It was built to enter an unknown territory beyond the Standard Model. Despite its great success in explaining the building blocks and forces of our universe and its strong experimental confirmation, the Standard Model is not complete and fails to address some observed mysteries. The experiments at the LHC may provide answers to some burning questions like how particles acquire mass or why the universe has more matter than antimatter.

During the initial phase of LHC operations physicists keep their eyes on every known elementary particle. Most of them were successfully rediscovered within weeks only, e.g. bound systems of quarks and antiquarks (Charmonium and Bottomonium, originally discovered in 1974 and 1977), unbound heavy Top Quarks (first discovered in 1995) and W and Z Bosons (discovered at CERN in 1983). In order to reliably discover new particles in proton-proton collisions, it is necessary to assign known particles to LHC events unambiguously. This is the particle-physicists real challenge and results in quite a bit of detective work! However, once the known particles are tracked down and identified, they are used to not only confirm previous results but also to show what already-known physics looks like in the new high energy environment of the LHC. And this is the key to discover new physics!

In our study, the Z boson – one of the mediator of weak interactions – is the particle of interest. By rediscovering the Z at LHC we can learn about the physics at such high energies, and in this way hope to discover new and exciting Nature’s phenomena!