Colliders of the future

Just over a year ago scientists investigating data from the Large Hadron Collider confirmed the discovery of the Higgs Boson - the holy grail of the Standard Model of particle physics that underpins scientists´ understanding of the fundamental workings of our universe. Exactly what sort of collider should come next is a matter of debate. Options for a successor range in size and feasibility, but a central question is what the machine should be colliding. The LHC collides opposing beams of either protons or lead nuclei, which are made up of neutrons. Making a decision about what kind of collider to build depends on what you expect to find. The Higgs Boson was discovered to have a mass of 125GeV (gigaelectronvolts), well within the 1TeV (teraelectronvolt) collision energy scope of proposed lepton colliders. But if new physics beyond the Standard Model such as supersymmetry and string theory exists, as many theorists expect, collision energies beyond the refitted LHC´s 14TeV are widely considered essential. The most technologically mature option is the International Linear Collider (ILC) - an electron-positron collider with an initial collision energy of 500GeV and the potential to upgrade to 1TeV. The technology is well established, with a smaller version running at the DESY research centre in Hamburg.