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How to find a new particle

  1. Jun 26, 2014 #1
    To find a new particle, the energy and momentum of the (decayed) particles are measured
    Evaluate the expression m^2 = E^2 - p^2 and plot a histogram.

    I just don't understand why there is a resonance particle if there is a peak in the histogram.
    Is it because the probability is very high and we regard it as a particle ??
     
  2. jcsd
  3. Jun 26, 2014 #2

    Simon Bridge

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    Where else would the peak come from?
     
  4. Jun 26, 2014 #3

    Bill_K

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    A threshold cusp, for one thing. http://arxiv.org/abs/hep-ph/0406293

    Indication of a resonance comes not just from a peak in the partial-wave scattering amplitude, but also a rapid increase in its phase. This recently played a role in the identification of Z(4430) as a candidate for a four-quark state. http://arxiv.org/abs/1404.1903
     
    Last edited: Jun 26, 2014
  5. Jun 26, 2014 #4

    Simon Bridge

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    ... OK, but I wanted HAMJOOP to think about it first.
    (In the context in which the question was asked...)
     
  6. Jun 27, 2014 #5

    Bill_K

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    Sorry, I just thought it was an interesting question. Did I get it right? :smile:
     
  7. Jun 28, 2014 #6

    Simon Bridge

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    Well it is the interesting form of the original question yes.
    A narrow resonance in a spectra could be a wigner cusp - usually a scattering experiment... occurs near the threshold where one channel comes to dominate another one.

    Particle detection experiments try to avoid these thresholds.
    It's the other half fo the answer OP is looking for. The graph, by itself, is not the whole story.
     
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