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In my text book it talks about about protons colliding: to demonstrate the idea of pair production and quark confinement. In both scenarios two protons collide (the energies of each are not stated only that one is 'high speed' and the other has 'enough energy'). 1 scenario is that two protons collide and antiproton a proton and energy is given off 2 scenario is that two protons collide and a meson is given off with energy What is the difference?
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  • $\begingroup$ Are you sure about those processes? Neither of the two are possible the way you wrote them because of baryon number conservation. $\endgroup$ – FrodCube May 16 '17 at 15:46
  • $\begingroup$ @FrodCube I have edited the question with the extract from my book. For all I can see that is what it's saying. $\endgroup$ – Aaron May 16 '17 at 15:54
  • $\begingroup$ The diagram showing pair production should show two protons and anti protons. Not just 1 antiproton $\endgroup$ – Aaron May 16 '17 at 15:56
  • $\begingroup$ What does happen when two protons collide? $\endgroup$ – Aaron May 16 '17 at 16:00
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    $\begingroup$ @garyp looking at the actual pictures I see no errors. The $p+p\to p+p+p+\bar{p}$ diagram is right and the meson thing makes sense if you consider it only as a part of a bigger interaction. There he only wants to explain that you can't free a quark from a hadron so he doesn't care to show you how you "break the bond" between the quarks. $\endgroup$ – FrodCube May 16 '17 at 16:19
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Aside from all the discussion in the comments, I'll answer your question.

Pair Production is a process in which some energy gets converted into a particle and an antiparticle. There are several examples of pair productions like the one your book uses an example where a proton and an anti-proton is created or some electromagnetic processes that can create an electron and a positron (anti-electron) from two photons.

Quark Confinement is a property of the strong interaction that prevents you from having free quarks. Every time some process might be able to break the bond between quarks, instead of getting free quarks as a result you get a natural pair production process that creates some quark + antiquark pairs so that at the end all the free quarks become hadrons (mesons or baryons). For example if you somehow manage to break the bond between one up quark of a proton and the other two quarks (one up and one down) instead of getting as a result $u+ud$ a pair $u+\bar{u}$ is created that bonds with the quarks you already have to give you $u\bar{u}+uud$ that is a $\pi$ meson and a proton.

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