Our quest to discover the fundamental laws of nature has led to the revelation that the laws of physics, and the particles they govern, exist because of underlying symmetries of nature, some of them lost since the big bang. One such lost symmetry might be supersymmetry. Just as for every particle there exists an antiparticle, supersymmetry predicts that for every known particle there also exists a superpartner particle. Part of the strong theoretical appeal of supersymmetry, an essential part of string theory, is its possible connection to dark energy and the fact that it provides a natural candidate for dark matter, the neutralino. James Siegrist, Universtiy of California, Berkeley, explains that one of the main goals in particle physics today is to not only discover new particles and forces but also to discover what principles explain their necessity. View the Video The discovery of supersymmetry is an immediate experimental challenge of particle physics, followed by the exploration of its structure and the properties of the superpartner particles. Particle accelerator experiments will uncover the role of supersymmetry in a unified theory and reveal whether the neutralino superpartner accounts for dark matter. The laws of nature derive from nature's symmetries; searching for new particles and forces means searching for new symmetries. One such symmetry might be supersymmetry, which predicts that for every known particle there exists a superpartner particle of the same mass. Experiments have not yet detected any of the superpartners; thus, if supersymmetry exists, it must be broken by unknown physics that makes superpartner particles heavy. Superpartner masses may be related to the Higgs field; supersymmetry provides a natural dark matter candidate, the neutralino. Experiments are searching for supersymmetry now; directly at the Tevatron and indirectly at the B-factories Belle and BaBar. The Tevatron may have enough energy to produce detectable signals of the lightest superpartners. The LHC should have enough energy to produce all or most of the superpartner particles, either directly or through the decays of other superpartners, to determine the pattern of superpartner masses and decays. CMS EXPERIMENT USCMS is a collaboration of US scientists participating in construction, software and physics analysis at the LHC's Compact Muon Solenoid experiment. Credit: CERN View larger image A Linear Collider would measure the properties of the superpartners very precisely, showing that they are indeed the superpartners of known particles; it could study the properties of the lightest superpartner (most likely the neutralino) with great precision. Do neutralinos behave like dark matter? Studies of the neutralino at a Linear Collider, combined with precision measurements of other superpartners, would produce a prediction for the cosmic relic density of neutralinos to determine whether the predictions are consistent with the dark matter hypothesis. Theoretical models for the physical mechanism that breaks supersymmetry are already constrained by data from Belle and BaBar. Future precision studies at Belle and BaBar, as well as from the future hadron B-factories BTeV and LHC-b will allow physicists to disentangle the flavor structure of supersymmetry through subtle changes to decays of B mesons. The MECO experiment will provide unprecedented sensitivity to the direct conversion of muons into electrons in nuclei; and some models of supersymmetric grand unification predict rates for this process that MECO can observe. Proceed to "HOW CAN WE SOLVE THE MYSTERY OF DARK ENERGY?"