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At a vertex of the diagram the usual conservation rules apply. Lepton number, charge and so on...


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Let me begin with David Miller's illustration of the Higgs mechanism. Miller depicts the Higgs field as a throng of journalists and politicians at a cocktail party. A famous politician, Margaret Thatcher (the only bad thing about this analogy), enters the room, playing the role of a particle. As she passes, the crowd gather around her, resisting her ...


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I would add to that list the masses and mixing angles of the three known neutrinos, which are just as arbitrary as the others within the confines of the standard model. This adds seven parameters to the 19 listed in the Wikipedia article https://en.wikipedia.org/wiki/Standard_Model#Construction_of_the_Standard_Model_Lagrangian


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We don't currently have an underlying theory for these parameters, we obtain their values experimentally, not theoretically. No, but one day I think the Standard Model will be enhanced to derive some of these paramaters from first principles. I've spoken to a medical doctor called Andrew Worsley who has some interesting "quantum harmonics" ideas about ...


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Within the standard model alone, all these parameters are independent, and to those you can add the masses and mixing angles of the neutrinos. Possible additional symmetries beyond the standard model suggest some relations between the gauge couplings, since renormalization group analyses based on these symmetries lead to unification of these couplings at ...


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I suggest you to read my answer here for a quick look into exotic hadrons. These particles mostly(at least so far) are very unstable appears for a short time and decay into another particles, hadrons and mesons. Hadrons made of 3 quarks and mesons one quark and its anti-matter. These unstable particles(resonances) have a quark content based on initial and ...


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In Scientific American, they said it was this specific grouping as illustrated, though with arbitrary coloring. It briefly stated how it must involve which quarks based on decay channels. I lost my hardcopy of the magazine so I can't easily look upmthe quotation now. I think it was not as you describe though... Yea, it's in Wikipedia now. In July ...


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A pentaquark is a particle made of five quarks. "Penta" means 'five' in Greek. Technically it could be made of any combination of quarks/antiquarks, though subject to some restrictions - see below. Quarks are bound by the strong force. In the same way as the electromagnetic force sees the (electric) charge of particles and causes interactions only within ...


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Here we will for simplicity just consider an arbitrary finite-dimensional complex$^1$ semisimple Lie algebra $\mathfrak{g}$. I) One may show that the CSAs are precisely the maximal toral Lie subalgebras of $\mathfrak{g}$. In particular CSAs are abelian. Also the Killing form $\kappa:\mathfrak{g}\times \mathfrak{g}\to \mathbb{C}$ (which is ...


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All processes involving neutrinos are weak mediated because neutrinos have zero electromagnetic and color charge. At tree level, all processes involving a $\nu + \bar\nu$ final state without other debris involve a time-like $Z^0$ (except neutrino NC scattering) which implies the annihilation of a particle/antiparticle pair (and will be suppressed relative ...


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I'm speculating here, basically looking at two considerations. Considering you used the term "radioactive decay" I'm going to look at this from a gross nuclear viewpoint rather than a particle/subnuclear viewpoint. If a nucleus is in it ground state, it would have no mode to lose energy without changing Z. So, in this case, no. If a nucleus is not in its ...


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In general, it is possible to derive "minor" concepts from a more general theoretical framework. This is the very definition of deductive reasoning, and it is in fact at the foundation of the scientific method. However, there are cases where the hierarchy of concepts is not so clear, in the sense that it is not always straightforward to decide which is the ...


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What you are looking for are explanations of effective field theory (for example see this review by Burgess http://arxiv.org/abs/hep-th/0701053) and chiral perturbation theory in particular (for example see this review by Scherer http://arxiv.org/abs/hep-ph/0210398, and here are some slides by Tiburzi that look good at first glance: ...


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Inflation, separation of gravity from other forces, separation of strong from electroweak force, and electroweak symmetry breaking, are all different events. It's easiest to start by describing the different sorts of fields involved. Quantum fields get classified by their "spin", which describes the angular momentum states that field quanta (particles) can ...


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Because you are looking only at the so-called global part, i.e. the part of the gauge transformation which resembles a group action. Recall that the vector bosons transform as $$ A_\mu \to g A_\mu g^{-1} - (\partial_\mu g) g^{-1}$$ where the first part is the global part of the gauge transformation, which tells you that $A_\mu$ transform in the Adjoint ...



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