There exist only quarks and leptons being elementary particles?

  • #1
519
0

Main Question or Discussion Point

Please teach me this:
I wonder whether there exist only quarks(6 quarks) and leptons being really elementary particles. Or there are many another types of particles?
Thank you in advance.
 

Answers and Replies

  • #2
45
1
Please teach me this:
I wonder whether there exist only quarks(6 quarks) and leptons being really elementary particles. Or there are many another types of particles?
Thank you in advance.
It depends on what and how you count.
The 6 quarks come in 3 colors; so one may be inclined to count in fact 18 quarks.
In addition to these spin 1/2 particles which you have mentioned there are also spin 1 fields, which are denoted as "particles" too - the so-called gauge bosons: 8 gluons, 2 W-bosons, the Z-boson and the photon. Last not least, there is the long awaited Higgs boson, predicted by the standard model but unobserved yet.
 
  • #3
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It depends on what and how you count.
The 6 quarks come in 3 colors; so one may be inclined to count in fact 18 quarks.
In addition to these spin 1/2 particles which you have mentioned there are also spin 1 fields, which are denoted as "particles" too - the so-called gauge bosons: 8 gluons, 2 W-bosons, the Z-boson and the photon. Last not least, there is the long awaited Higgs boson, predicted by the standard model but unobserved yet.
Just to make this list complete, the leptons include the electron, muon, and tauon, along with a corresponding neutrino for each of them, so a total of 6. Then you have to remember that all of these matter particles (quarks and leptons) have a corresponding antiparticle, so you have to multiply all those numbers by 2.

According to the Standard Model of particle physics, these are all the elementary particles. Everything else (including protons and neutrons as well as a whole zoo of other particles that have been detected) can be considered composite collections of these elementary quantum fields.
 
  • #4
980
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That's still neglecting the fact that in the weak theory there's only a single handedness, but that flavour basis isn't the same as the QCD flavour basis... Which all complicates the counting a little bit...
 
  • #5
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That's still neglecting the fact that in the weak theory there's only a single handedness, but that flavour basis isn't the same as the QCD flavour basis... Which all complicates the counting a little bit...
How does this complicate the counting?
 
  • #6
arivero
Gold Member
3,295
57
I think there are two ways of counting, mainly: helicity states, and then we go up to 96, or mass eigenstates, and then we are down to 12.
 
  • #7
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what about the gravitron which is also unconfirmed but greatly anticipated?

iirc, LIGO is going through their data now.
 
  • #8
arivero
Gold Member
3,295
57
W, Z, foton and gluons are also elementary quanta. But you can stick to old terminology, and call them not particles, but forces.
 

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