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How do you know that a particle is strongly interacting?

  1. Aug 29, 2011 #1
    when physicists discovered particles other than nucleons, before the quark model, how did they know they are "strongly" interacting, is it the half-life?
     
  2. jcsd
  3. Aug 30, 2011 #2

    tom.stoer

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    Yes, half-life i.e. decay width (and in general strength of interaction, i.e. scattering cross section, but that doesn not apply to outgoing particles, of course)
     
  4. Aug 30, 2011 #3

    Bill_K

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    No, not the half-life, it has to do with production. Particles are typically produced via strong interaction and decay via weak interaction. Strong interactions have a characteristic time scale of 10-23 sec, whereas most decays are 10-13 sec or thereabouts.

    However the shortest lived known particle, the top quark, decays into a W boson and a bottom quark with an estimated lifetime of 5×10−25 sec. Even this is a semi-weak interaction.
     
  5. Aug 30, 2011 #4

    tom.stoer

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    I think we are not talking about quarks but e.g. hadrons.

    How do you distinguish a meson and its decay channels from a myon or tau lepton? or from a neutrino? especially when you are capturing data from cosmic radiation? via half-life of the paricle; production is not under control.
     
  6. Aug 31, 2011 #5

    Bill_K

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    Ok, here's a question for you. I have a particle with a mass of 1.8 GeV and an observed lifetime of 3 x 10-13 sec. From the relationship that you believe exists connecting a particle's lifetime with its strong interactions, tell me whether you think this particle is a hadron or a lepton.
     
  7. Aug 31, 2011 #6

    tom.stoer

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    I cannot distinguish whether it's a hadron or a lepton, but I can GUESS that it decays only weakly.
     
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