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How are elementary particles born?

  1. Feb 18, 2006 #1

    If we use the Friedman Equation form to find time(excpected) for a given particle's Rest Mass energy as our input value, does it mean that the most energetic particles were 'born' first and the lighter particles 'born' later on in time in a linear, sequential order?

    eg. T quark (174Gev)---->Z Boson(~90GeV)----->W Boson(~80GeV)---->B Quark(5GeV)------>Tau(~1777MeV)-----Proton(~938MeV)----->Electron(0.511MeV)------>etc...

    Does the order of their Rest Mass energies mean they were 'born' in that order too?

    Thanks, I'm very puzzled about this.
  2. jcsd
  3. Feb 18, 2006 #2

    Physics Monkey

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    A couple of things here. It's important to remember that everything in the Standard Model gets its mass from the Higgs vacuum expectation value (with the possible exception of right handed neutrinos). So in the early universe before the electroweak symmetry breaking everybody in the Standard Model looked a lot different i.e. they were all massless. Also, one of the roles of inflation is to dilute the density of topological relics like monopoles and so forth (this is necessary because we don't see monopoles). However, inflation diluted the density of everything else too! After inflation ended and the universe reheated, generally only those particles with mass less than the reheating temperature could be produced. In this sense, all the types of particles we see now were "born" at the time of reaheating.
    Last edited: Feb 18, 2006
  4. Feb 27, 2006 #3
    I don't understand you Physics Monkey.

    You said after inflation, there was a 'reheating'? I thought the Universe's temperature has been steadily declining since then. Are you suggesting that inflation happened so fast that a period after it was needed to reach thermal equillibrium?

    Please, give clearer arguments, I'm trying to follow you, but its difficult,
  5. Feb 27, 2006 #4

    Physics Monkey

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    Sorry if it was over your head, Order. It seemed based on your first post that you had a fair technical knowledge in this area.

    The short story follows. The universe rapidly expanded during inflation, and the result was a very cold empty place. The matter and energy we now see came from a reheating phase when the "inflaton field" that was driving inflation decayed into other kinds of matter. The result was a hot universe that has since cooled.
  6. Mar 2, 2006 #5

    Ok, I'm following you now.

    1) What time period did this 'reheating phase' take place in? Inflation ended at 10*-32 seconds, so from then to when did this phase take place?

    2) How did the 'Infation field' decay into matter and what type of matter did it decay into?

    Please feel free to speak technically, don't let me dumb your answers down.

    Thanks again!:!!)
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