Rachel Yohay

At the Large Hadron Collider (LHC), the world’s highest energy accelerator at 7 TeV center-of-mass energy, I am searching for evidence of a theorized symmetry of nature called supersymmetry. At the heart of supersymmetry is the notion that there exists a fundamental relationship between matter particles (fermions) and force carriers (bosons). If supersymmetry exists in the form I’m studying, then proton-proton collisions at the LHC should produce a pair of supersymmetric gluons (gluinos), each of which then decays into quark jets, a photon, and a supersymmetric graviton (gravitino). The Compact Muon Solenoid (CMS) detector, located at access point 5 of the LHC ring, is a general-purpose particle detector well equipped to find the high-energy jets and photons characteristic of supersymmetric particle production and decay. However, the signature gravitino does not interact with any of the detector material. Its existence can only be inferred by applying conservation of momentum to all of the particles in the event which do interact with the detector. Therefore, CMS must be calibrated well enough that physicists can trust the so-called “missing energy” extracted from the collision event, and equate it with the energy and momentum carried by the gravitino. Should supersymmetry exist in nature, an excess of events with two high-energy photons, a number of high-energy jets, and large missing energy will be observed in the data. We expect to be able to observe or rule out many variants of supersymmetric models with only the first year's data produced by the LH