Discovery Scenarios

Supersymmetry

Simulation of the creation of superpartner particles at the LHC, as seen in the CMS detector at CERN.

A major obstacle to Einstein’s dream of a unified theory is the clash of the laws of the large with the laws of the small. Quantum mechanics reveals an unruly subatomic world, bubbling with particles that pop into existence out of nowhere and then disappear. On the scale of the universe, we see stars and galaxies that proceed smoothly according to immutable laws of gravity. To reconcile the apparent contradiction, new principles must exist that bring order to the quantum universe. Supersymmetry, a prediction of string theory, could be the key.

Supersymmetry says that all known particles have heavier superpartners, new particles that bring order to the subatomic world. The lightest superpartner is a likely candidate for dark matter, thus perhaps also explaining the structure of the cosmos. Supersymmetry could even explain the existence of the Higgs particle, and be responsible for many Higgs-like cousins.

Some of the heaviest superpartners may be copiously produced at the LHC. They would then decay to the lightest superpartner and dozens of ordinary particles, leaving spectacular but complicated signals in particle detectors. A linear collider would be best suited for producing the lighter superpartners. Linear collider experiments could focus on one type of superpartner at a time, measuring their properties cleanly enough to detect the symmetry of supersymmetry, and to reveal the supersymmetric nature of dark matter. In this way, linear collider physicists could discover how supersymmetry shapes both the inner workings and the grand designs of the universe.