![]() ![]() At the same time, these clues have motivated Institute theorists to pursue a radical transcription of our ordinary physics formulated in space and time in terms of a theory without explicit reference to spacetime. Most recently, clues provided by Feynman diagrams have led to powerful new methods that are revolutionizing our ability to understand the fundamental particle collisions that will occur at the Large Hadron Collider (LHC). Members of the Institute have played leading roles in the development of their use, from Freeman Dyson in the late 1940s and early 1950s to the current generation of theoretical physicists in the School of Natural Sciences. Instead, a “holographically dual” formulation of the problem has been developed (Figure 5), where the gluon scattering in a four-dimensional conformal field theory (CFT) is related to a tractable string theoretic calculation in a higher-dimensional anti–de Sitter (AdS) space.įor sixty years, Feynman diagrams have been an essential calculational and conceptual tool for theoretical physicists striving to deepen our understanding of the fundamental forces and particles of nature. Scattering processes involving very strongly interacting gluons are impossible to calculate using Feynman diagrams. Recent work has revealed a direct relationship between BCFW terms and “twistor diagrams” (Figure 4), which reduce the calculation of amplitudes to simple multiplication rules. For example, this six-gluon process is only not zero when the points in twistor space representing the six gluons lie along two intersecting lines (Figure 3). These powerful new diagrams were developed at the Institute, and were made possible by the realization that the amplitudes possess remarkable properties when the gluons are associated with points in a geometric setting known as “twistor space,” rather than ordinary spacetime. Figure 2 represents the complete set of BCFW diagrams required to calculate the same process. The amplitude is obtained by adding up a total of 220 diagrams.īecause the number of Feynman diagrams needed to calculate an amplitude can climb into the thousands, increasingly clever tricks have been developed to bypass their direct computation. Each Feynman diagram pictorially represents a specific way in which this process can happen, and is associated with a complicated mathematical expression. This process will occur several hundred times a second at the LHC. The many graphs depicted in Figure 1 represent a small sample of the Feynman diagrams necessary to compute the amplitude for producing four outgoing gluons from the collision of two incoming ones. Feynman diagrams provide a way of calculating scattering amplitudes in a manner that is consistent with quantum mechanics and special relativity and more recently they have been used for increasingly complex calculations related to the physics being probed at high-energy particle accelerators, such as the Large Hadron Collider (LHC). Their broad utility was due initially in large part to the seminal work of Freeman Dyson, Professor Emeritus in the School of Natural Sciences. some flavour specific diagrams involving supersymmetric particles appear under Flavour physics.Physicists have used Feynman diagrams as a tool for calculating scattering amplitudes that describe particle interactions for more than six decades. Be aware that some diagrams may appear in unexpected groups, e.g.
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