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Natural Science Forum / Physics / Relativity / January 2005Standard model accurately describes elementary particle interactions 99% of the time
In another post Tom Roberts wrote: 'The standard model of particle physics is the currently-accepted theory of the interactions of elementary particles; it accurately describes about 99% of what we know about particle interactions. The standard model is a quantum-mechanical gauge theory of strong, weak, and electromagnetic interactions.' I am certainly no expert on the standard model but I do know a little of it. My understanding is that no elementary particle interaction is not described by the standard model hence I am very curious as to exactly what Tom meant. I wonder if Tom, or anyone else, could elaborate? Thanks Bill > In another post Tom Roberts wrote: >> 'The standard model of particle physics is the currently-accepted theory of [quoted text clipped - 3 lines] > My understanding is that no elementary particle interaction is not described > by the standard model hence I am very curious as to exactly what Tom meant. There are now enough measurements of neutrino oscillations that it is pretty clear that at least some neutrinos have nonzero mass. The standard model does not include massive neutrinos. But a straightforward extension of the standard model does, and fits the data quite well (but there are rather large errorbars, hence the desire for a neutrino factory). Neutrino masses are really input parameters to the standard model, and they were set to zero based on the data available when the SM was formulated. Nonzero neutrino masses requires a mixing matrix to be added to the model, too -- this corresponds to the quark mixing for weak interactions that has been in the SM from the beginning. The bounds on neutrino masses remain so small they are not observable in other tests of the model (e.g. measurements of muon decay). Google "neutrino oscillations" for more.... The NuFACT04 website seems to be down, but google's cached pages have valid links to talks by (e.g.) Valle, Mitsui, Kajita, and others.... [In case you have not guessed, this is related to my current research; I attended NuFACT04, and gave several talks at the following MICE collaboration meeting.] Tom Roberts tjroberts@lucent.com > There are now enough measurements of neutrino oscillations that it is > pretty clear that at least some neutrinos have nonzero mass. The standard [quoted text clipped - 18 lines] > research; I attended NuFACT04, and gave several talks at the > following MICE collaboration meeting.] According to the Standard model, anti-neutrino + proton = neutron + positron However, if I write the above equation as energetic electron + proton = neutron Would this explain the Cowan-Reines Experiment? No. The antineutrino is required for angular momentum conservation and lepton number conservation. PD Koobee Wublee: >> There are now enough measurements of neutrino oscillations that it is >> pretty clear that at least some neutrinos have nonzero mass. The standard [quoted text clipped - 26 lines] > >energetic electron + proton = neutron e- + p -> n + \nu otherwise known as electron capture in nuclei. > In another post Tom Roberts wrote: > [quoted text clipped - 7 lines] > My understanding is that no elementary particle interaction is not described > by the standard model hence I am very curious as to exactly what Tom meant. No part of the standard model addresses the gravitational elementary particle interaction. > I wonder if Tom, or anyone else, could elaborate? > > Thanks > Bill |
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