![]() When a core electron is removed, leaving a vacancy, an electron from a higher energy level may fall into the vacancy, resulting in a release of energy. The Auger effect or Auger−Meitner effect is a physical phenomenon in which the filling of an inner-shell vacancy of an atom is accompanied by the emission of an electron from the same atom. (b) illustrates the same process using X-ray notation, KL 1L 2,3. The final atomic state thus has two holes, one in the 2s orbital and the other in the 2p orbital. An electron from the 2s level fills in the 1s hole and the transition energy is imparted to a 2p electron which is emitted. An incident electron (or photon) creates a core hole in the 1s level. (a) illustrates sequentially the steps involved in Auger deexcitation. And which case you imagine would depend on the reference frame of your imaginary observation point.Physical phenomenon Two views of the Auger process. And if you imagine the electron interaction occurring first, then you would imagine that the W boson is a W -, but if you imagine the proton interaction occurring first, you would imagine that the W boson is a W +. However, if you imagine this occurring as an actual process, a specific one of the infinite set of processes represented by the Feynman diagram, then you would imagine one of the interactions occurring before the other. The diagram actually represents the sum of all possible orderings. Sure, you might draw it one way or the other, but the information of which interaction happens first is not part of the information that is represented by the Feynman diagram. Those other fluctuations are more or less what we call virtual particles.Īnd so what you are saying is that if the Feynman diagram shows the electron interaction happening earlier than the proton, then it should be a W-, but if the proton appears earlier on the diagram then it's a W+ ?Īctually, what I'm saying is that the Feynman diagram does not show the electron interaction happening earlier than the proton interaction, or vice versa. Roughly speaking, you can have a particular shape and size of "bump" in a field that does correspond to a real particle, but you can also have other bumps/fluctuations that are too small to correspond to real particles. See, the thing is that Feynman diagrams describe fields. Or rather, they do exist, but they're not particles. Hm, well, I guess you could say that they don't really exist. This actually does turn out to be the case, since the mathematical expression that corresponds to a Feynman diagram is a Lorentz-invariant amplitude. This suggests that it's kind of arbitrary which one you call it, and when you go to do the math, it should work out in a way such that it doesn't matter which order you see the vertices in. If events A and B are the two vertices in the Feynman diagram, then it stands to reason that one observer might see the exchanged boson as a W + while another observer sees it as a W. One observer might see event A occur before event B, and another observer might see event B occur before event A. As you may know, special relativity tells you that different observers won't agree on the time ordering of events at different locations in spacetime. ![]() In fact, if you think about it, for some cases, whether you see the W boson as a W + or W - is reference-frame dependent. Because the Feynman diagram represents all the possible ways of associating a vertex with a spacetime point, it includes both possibilities. But if the npW vertex has the earlier time, then it looks like the proton emits a W boson, which means it's a W +. ![]() In all the cases where the eνW vertex is "tagged" with an earlier time than the npW vertex, then it looks like the electron emits a W boson and turns into an uncharged particle, which means you would call that a W. In an exact physical process, then each of these vertices would be associated with some specific coordinate in spacetime, but the Feynman diagram represents the sum of all possible ways of associating those vertices with spacetime coordinates.įor example, in the diagram you're looking at, there are two vertices: one involving an electron, a neutrino, and a W boson, and the other involving a W boson, a neutron, and a proton. What I mean by "interaction" here is just a meeting of three or more lines. You have to remember that Feynman diagrams are a way of representing a set of individual interactions that occur, not an exact physical process. There's really no difference - it's just two different ways of drawing the same thing. ![]()
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