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I Question about relative abundance of particles before annihilation

  1. Nov 21, 2015 #1
    I am looking to correct my understanding about the relative abundance of particles and antiparticles created before the two periods of annihilation:
    (1) protons/neutrons and anti-protons/anti-neutrons, and
    (2) electrons and positrons.​

    In a previous thread
    I presented my understanding about this, but I have since decided that I made some mistakes. I had previously assumed that the relative rest mass of particles was relevant to their relative abundance, but I overlooked that at temperatures high enough for all particles to be created with relativistic speeds the relative rest masses were insignificant.

    So, what I would like is someone to either to confirm or correct the following ideas:
    (a) Well before the period of (1) annihilation, the relative abundance of (1) particles would be about the same as that of the (2) particles.
    (b) Just before (1) annihilation, the (1) particles would not be relativistic when created, but the (2) particles would be.​
    Question 1: What would the relative abundance of (1) and (2) particles be just before (1) annihilation?
    (c) After (1) annihilation, but before (2) annihilation, the number density of (2) particles would decline as the scale factor a increased with expansion. This decline would be inversely proportional to a3. However, the decline should be faster than this because the temperature is also declining, and that should also have an effect on the equilibrium between the creation of (2) particles and their mutual annihilation.​
    Question 2. How does the equilibrium abundance of a protons and electrons depend on temperature.

    I will have some more questions later, but getting answers to the above is my first priority.
  2. jcsd
  3. Nov 26, 2015 #2
    Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?
  4. Nov 26, 2015 #3
    Hi @Greg Bernhardt:

    Thanks for the automated encouragement. I am not sure that it is easy for anyone to answer any of my questions, or to find a reference that would help. I guess I was too optimistic in putting this post together. I think the best thing I can try is to start a new thread with just one of the questions.

  5. Nov 27, 2015 #4


    Staff: Mentor

    Thread closed as the OP has started a new one.
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