-2

Which fundamental particles are involved in an anti-matter collision and what is the result of this, only photons?

Frederic Thomas
  • 9,695
Martin
  • 1
  • 1
  • Your question is rather broad, it would be better if you can give it more focus. There's some useful info here: https://en.wikipedia.org/wiki/Annihilation#Proton-antiproton_annihilation You may also find my answer here helpful: https://physics.stackexchange.com/a/451337/123208 – PM 2Ring Apr 04 '20 at 06:16
  • 1
    What do you mean by a fundamental particle "having" an anti-matter collision? – ACuriousMind Apr 04 '20 at 11:11
  • I can only find certain things are not enough . Sorry the question was broad. Scientific pages state from a collision between matter and anti-matter , photons are produced. With this, what matter was used in the collision? Surely not an elementary particle past the boson? – Martin Apr 04 '20 at 13:09

2 Answers2

1

Any fundamental particle can in principle collide with its antiparticle and annihilate.

In practice this has been done on a reasonable scale only with positrons/electrons (as in PET scanning, as well as particle colliders) and protons/antiprotons(at the Fermilab Tevatron and the CERN Antiproton Decelerator, for example)

Such an annihilation can produce any particle-antiparticle $P \overline P$ pair, provided (1) there is enough energy, at least $2 M_P$ and (2) there is some sort of coupling, which rules out some proposed dark matter candidates.

The reason photons feature in descriptions ('matter and antimatter annihilate to gamma rays...') is that most of our experience is with low energy positrons and electrons, and the photon is the only particle lighter than the electron (apart from the neutrino, but see (2) above). Low energy positrons (from nuclear sources) annihilate with stationary electrons to produce photons but higher energy collisions, as happened at PETRA and LEP, can produce pairs of muons or pairs of quarks. Low energy proton-antiproton annihilation produces mostly pions.

RogerJBarlow
  • 10,063
  • Good answer +1. Could you expand a small bit on the coupling issue, in particular regarding the production of neutrinos from an electron-positron annihilation? – Dale Apr 04 '20 at 14:24
  • 1
    A low energy electron and positron have enough mass to produce a neutrino antineutrino pair, but the annihilation proceeds through a virtual Z rather than a virtual photon (or, to put it another way, it's a weak interaction rather than an electromagnetic one) so the probability is very very very small. – RogerJBarlow Apr 04 '20 at 14:33
  • 1
    Sorry I was unclear. I meant to expand in the answer itself. It would further refine this already good answer – Dale Apr 04 '20 at 15:01
  • Thank you so much for your time and response. So, your first statement “in principle”, what does this exactly mean with your comment. 2. Where is the position found in the natural world literally. 3. The collision of two particles produces two particles? 4.what is coupling apart from the two holding together as one. Where is the conservation of energy law here in the destruction of elementary particles. Sorry to pull at every thread – Martin Apr 04 '20 at 22:37
  • 'In principle' is the contrast to 'in practice' in the next para. In principle, say, an $\Omega^-$ could annihilate with and $\overline \Omega^+$ but you could never design the experiment (2) Potassium 40 decays produce positrons. So bananas are positron sources at a VERY low level. They also occur in cosmic rays from photon showers (3) Some times two, but also 3 or more. There is no specific restriction on the number. (4) Coupling is jargon for any interaction, as in a Feynman diagram. Responsible for holding-together and for decays/scattering as applicable. (contd)
    • – RogerJBarlow Apr 05 '20 at 08:29
  • (5) Conservation of Energy is everywhere. But you have to remember to include the rest mass energies. – RogerJBarlow Apr 05 '20 at 08:31