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The origin of baryon number

  1. Jan 10, 2014 #1
    I'm doing a little research on quarks on stumbled upon the baryon number. Wikipedia says that the notion predates the quark model. I have no clue why particle physicists were motivated to introduce it before flavour quantum numbers came to the scene.

    So... What's the (historical) origin of baryon number?
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  3. Jan 10, 2014 #2

    Vanadium 50

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    Baryon number as a conserved quantity was to explain why you didn't see decays like p -> e+ pi0.
  4. Jan 10, 2014 #3

    Meir Achuz

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    In all known experiments so far, the number of baryons is conserved, and the notion goes back to the early beta decay experiments. This has nothing to do with quarks, but most quark models incorporate baryon number conservation. Some extended symmetry theories predict proton decay into leptons and mesons which would violate baryon number conservation.
  5. Jan 10, 2014 #4

    Simon Bridge

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    Well baryons were observed before the quark model and their behaviors documented.

    One of the things researchers try is to sort things into groups and see what makes sense.

    Doesn't it seem reasonable to count matter as +1 and antimatter as -1? Once you've done that for nucleons, and looked at what happens to the numbers in various nuclear reactions, what would be a sensible number to give mesons?
  6. Jan 10, 2014 #5


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    Where the quark model helps explain baryon number is motivating why baryon number of mesons is zero (quark/antiquark pair). Baryon number could be replaced with quark number, but everyone was used to baryon number.
  7. Jan 10, 2014 #6
    Thanks everyone for your input! Got the type of answers I wanted.
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