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Why does the proton have no excited states?

  1. Sep 24, 2011 #1
    I've never heard of any excited states of the proton. Why?
    By "excited state" I mean something with the same composition (uud) that decays to the proton (plus photons etc.) with nearly 100% branching ratio.
     
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  3. Sep 24, 2011 #2

    jtbell

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  4. Sep 24, 2011 #3
    Thanks! One question, though. Does the [itex]\Delta^+[/itex] decay to [itex]p\pi^0[/itex] or to [itex]n\pi^+[/itex] more often? According to Wikipedia on Delta baryons both decay modes exist.
     
  5. Sep 25, 2011 #4

    jtbell

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    In order to answer that question, I'd go to the Particle Data Group and search through the baryon tables, but you might as well do it yourself. :wink:

    http://pdg.lbl.gov/
     
  6. Sep 25, 2011 #5
    I actually check PDG before I posted the previous reply, but I got lost...
    I went to Particle Properties -> Baryons, and found a list of reviews. I admit I often don't understand the terminology, but none of them seems to have any information on Delta+ branching ratios.
     
  7. Sep 25, 2011 #6

    Vanadium 50

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    That's because the decays are given by Clebsch-Gordon coefficients and the assumption is anyone can calculate them.
     
  8. Sep 25, 2011 #7

    Bill_K

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    Last edited by a moderator: Apr 26, 2017
  9. Sep 25, 2011 #8

    Chronos

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    Neutrons decay into protons [plus electons and electron antineutrinos].
     
  10. Sep 25, 2011 #9

    Meir Achuz

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    The ratio of Delta-->pi0 n/Delta-->pi- p is determined by isospin to be 2:1.
     
  11. Sep 25, 2011 #10

    Meir Achuz

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    Thereare a large number of excited states of the proton besides the Delta.
    All the states called N* or Delta can be considered excited states of the proton.
    They decay mainly into pions and a proton or neutron.
    There is a small branching ratio into photon and nucleon.
     
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