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Re: [Phys-L] Particle physics

I'd suggest www.particleadventure.org as a good place to start.

I don't care for the vague phrase "particles form from the energy", though it contains a grain of truth; energy is one of several quantities that are conserved in all particle interactions. (Other conserved quantities include momentum, electric charge, and baryon number.)

Some particles are made of quarks and some aren't. Some particle reactions can be understood mainly as rearrangements of quarks; some can't.

You might want to try to understand a very simple reaction such as e+ e- --> mu+ mu-. No quarks at all in the initial or final state! The intermediate state (to a good approximation at reasonably low energies) is a virtual photon, which carries energy, momentum, etc. Note that a photon is not merely energy; it's a quantum of the electromagnetic field and this is why it's able to produce a pair of electrically charged particles such as muons.

Any time a particle decays into other particles, the latter can be called daughter particles. This terminology is the same as in ordinary nuclear decay processes (alpha, beta, etc.).

"Fundamental" is a relative term. So far, nobody has successfully explained leptons or quarks or gauge bosons (photon, gluons, W, Z) in terms of anything else, so for the time being we often call them "fundamental". The Higgs may or may not be as fundamental as any of these. In the "simplest" versions of the theory it is, but our actual knowledge of the Higgs, from experiments, is pretty incomplete so far.

Dan


On Jun 18, 2013, at 10:00 AM, Paul Lulai <plulai@stanthony.k12.mn.us> wrote:

Hi.
I am working to create some materials for 20th century physics & particle physics. Before I do, I need to understand some of it.
When particles collide inside cern / fermi / slac, and produce particles, do the particles form from the energy of the collision?
Do the particles form because the quarks rearrange?
When massive particles decay to daughter particles, are the daughter particles composed of fewer fundamental particles?

Now, I believe a particle can be made from energy for to particle interaction (photon vs photon). So I thought an interaction in a detector would produce particles at least (!) partly due to the energy of the interaction, not just rearranging particles like quarks.
I believe muons are fundamental, and decay (perhaps there is a better term) into particles. Would the particles a myob decays into be considered daughter particles?

One more...
Is the higgs boson fundamental?


Thanks for your help.

...::. Sent from a touchscreen.::...
Paul Lulai