4/2/2023 0 Comments Feynman diagrams![]() The reason for this is Feynman’s particular way of doing quantum mechanics, which is to sum over all possible processes. There might be more than one at lowest order, so it is important to draw all possible. 3 For a given process draw an FD of lowest order. The higher the order, the greater the complexity and the more terms in the corresponding series. Figure 1 above, for instance, is second order. The order of a FD is the number of vertices in it. A vertex always has three lines attached to it: one boson, one fermion pointing in, and another fermion pointing out. A photon in the initial or final states is represented, respectively, by a wavy line meeting a vertex, or . A positron in the initial (final) state reverses the direction of the arrows. An electron in the initial state is represented by a solid line with an arrow pointing toward the vertex, , but in the final state it is represented by a line with an arrow pointing away from the vertex, . Three symbols are used to depict QED processes: solid straight lines for the fermions, wavy lines for photons, and dots or vertices for the interaction. But I will assume that there is a clear difference between the two possibilities that I will eventually discuss: Feynman diagrams might be typical models or representations, on the one hand, or they might be something very different from that, on the other. I can’t say what that similarity is, since there is no consensus on the nature of similarities in models at all. The question is much more interesting when we put a reasonable constraint on it and require some appropriate sort of similarity. Of course, this is silly and nothing useful is likely to come of it-but it could be done, which is the point. For instance, I could stipulate that Feynman’s first diagram stands for Napoleon and his second for Kutuzov. If we take a sufficiently liberal view, then there could hardly be a question about Feynman diagrams representing or modeling physical reality. Add the pepper as a second electron in orbit around the salad and we have a model of helium. That same salt and salad is used by another person to model a hydrogen atom they play the respective roles of electron and nucleus. At dinner, someone says a salt shaker stands for Napoleon while the potato salad represents La Grande Armée. Darcy represent gender relations and class tensions in Regency England. In Pride and Prejudice Elizabeth Bennet and Mr. To appear in the proceedings.It is a truth universally acknowledged, as Jane Austen might say, that anything can stand for anything else. Comment: Invited Talk at Seesaw (1979-2004), Fujihara Seminar, Neutrino mass and Seesaw mechanism, Feb 23-25, 2004, KEK, Japan. We explicitly show that in a class of SUSY SO(10) GUTs there exist cases where LFV and CP violation in B-physics can constitute a major road in simultaneously confirming the ideas of Seesaw and low-energy SUSY. In Grand Unified theories, these effects can be felt even in hadronic physics. Indeed, even when supersymmetry breaking is completely flavour blind, Renormalisation Group running effects are expected to generate large lepton flavour violating entries at the weak scale. ![]() contrary remains unobservable in the SM seesaw. ![]() SUSY seesaw exhibits a potentially striking signature: a strong (or even very strong) enhancement of lepton flavour violation (LFV), which on the. After a quarter of century of intense search for new physics beyond the Standard Model (SM), two ideas stand out to naturally cope with (i) small neutrino masses and (ii) a light higgs boson : Seesaw and SUSY. ![]()
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