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This is going to be a strange question, but here we go. I'm working on a computer puzzle game that will simulate subatomic particle collisions. I am not a physicist by training, but I do dabble. I would like the game to be loosely based on reality, and I've been trying very hard to find a resource that could outline, simply put, what happens when:

proton <-> proton collides
electron <-> positron collides
electron <-> electron collides
...etc.

It would be even more interesting to see what happens at varying energy levels (as energy, in the game, will be a resource). If you think think this question is a waste of time, I apologize in advance.

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  • $\begingroup$ There really isn't a way to make such lists simple once the energies reach interesting levels. You are playing in quantum mechanics land and anything that is not forbidden is mandatory. Worse some things that are forbidden in one channel may be allowed in another (axial scattering in $\vec{e} + p$ scattering as in $G^0$ for instance). Even the notion of "collision" gets very fuzzy very fast. The particles are said to "interact". $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Jul 27, 2012 at 2:10
  • $\begingroup$ For instance, just in electron--nucleus scattering we have elastic, nuclear excitation, resonant pion production, resonant vector meson production, quasi-elasic nucleon knockouts, further resonance reaction and so on up to "deep inelastic scattering" in which the nucleus is blasted into itty bitty bits (to use a technical term). $\endgroup$
    – dmckee --- ex-moderator kitten
    Commented Jul 27, 2012 at 2:13

2 Answers 2

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Oh goodness... that is an immensely complicated topic. Many thousands of people have put in decades of work figuring out exactly what happens when two subatomic particles collide. The calculations are all done using quantum field theory, so I would say if you want to learn about the process involved in describing the outcome of a collision, read up on QFT - not necessarily in the full detail needed to do the calculations, but at least enough to know the basic overview of how it works. (I happen to be a fan of this book, if you know some quantum mechanics.)

I don't know of any master list of all the possible interactions that can occur when two particles collide. A good general guideline, though, is that anything that can happen will happen. In other words, when you collide two particles together, any set of particles that have the same conserved charges as the original particles can be produced. For example, imagine colliding an electron and a positron, both polarized such that they have spins pointing in opposite directions. The pair together have zero charge, zero total spin, zero lepton number, zero baryon number, etc. So any set of particles that also has all those charges totaling zero is a potential result. At low energy, you'll probably get two photons, but at higher energies you could get, say, a muon and antimuon, or even a proton and an antiproton. (Or two protons and two antiprotons, etc.) The requirement for production of massive particles is simply that the total energy of the colliding particles is at least the total mass (times $c^2$) of the particles produced.

Collisions between composite particles like protons are much more complicated than those between fundamental particles like electrons, because there are a lot more individual particles involved that can collide. What happens in these hadron collisions is typically that you get 2 or 3 high-energy jets, which are groups of particles that come out of the collision in roughly the same direction, along with a bunch of other lower-energy particles that emerge in random directions. Again, any set of products that obeys the relevant conservation laws is in general a possible outcome, but in high energy hadron collisions, you get so many product particles (hundreds or thousands) that basically anything can come out.

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In a sense these "games" exist, need large computing power and are called high energy physics monte carlos.

These are very complicated simulations of the reality of the experiment and include all the detector effects.

At the first level of the core of these HEP monte carlos there exist tables of "complete" possibilities of scattering products: all interactions are simulated with their probabilities according to the known physics of the time of the experiment, with correct balances of all quantum numnbers and conservation laws.

I suppose if you started reading the code of these programs you might extract just the generators and the tables and these could become the core of your game.

If you are serious you should try to find somebody familiar with GEANT to collaborate with, else spend a lot of time in reading up on the programs.

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