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Types of particles.

  1. Nov 21, 2003 #1
    Hi all,
    How many types of sub atomic particles are there?

    lets just list as many as possible.

    -benzun
    all for God.
     
  2. jcsd
  3. Nov 21, 2003 #2
    there are probably hundreds of subatomic particles, but there are only a few so-called elementary particles

    so let me list just those. i find making this list a little tricky, because it is hard to decide which particles i want to list as the same particle.

    there are two basic matter fields, the quark field, and the lepton field. there are three generations of each. the quark field has 3 colors, 2 isospin states (up type versus down type), 2 chiralities, and also comes in an antiparticle version. the up types have different hypercharge from the down types.

    the lepton field has 2 isospin states (electron versus neutrino), and the up isospin states (electrons) have different hypercharge from the down isospin states (neutrinos). they come in 3 generations, 2 chiralities, and also there is an antiparticle version.

    so depending on how you distinguish the various charges, there may be 2, 3, 8, or 16 in each generation (i am not counting antiparticles as distinct particles. if i do, then i should double all those numbers). counting all 3 generations gives 6, 9, 24, or 48.

    96 total when i count every particle with a different charge and its antiparticle.

    yikes

    then there are the bosons. 8 gluons, 3 weak mediators and one hypercharge generators, which are usually combined together according to electroweak unification to give the W±, the Z and the γ.

    for a total of 12 bosons.

    it kind of sounds like a lot when you add them all up, but its not as bad as it seems. its a lot simpler when you think of it like this: there are 2 types of matter, the quark and the lepton, each of which can be charged under 3 different gauge groups, times three generations.
     
  4. Nov 21, 2003 #3
    On the most basic (fundamental) level there are Gauge and Higgs Bosons, Leptons, and Quarks. There are six quarks and six antiquarks. They transform as doublets by generation;

    (u/d), (c/s), (t/b)

    The first generation contains the up and down quarks, which are eigenstates of isospin (Iz = 1/2). The second generation contains the charm and strange quarks; the charm quark has charmness (C) = 1, and the strange quark has strangeness (S) = -1. The third generation contains the top and bottom quarks; the top quark has topness (T) = 1, and the bottom quark has bottomness (B) = -1. Their antiparticles each have the opposite quark flavor number. One thing to remember here is that the sign of the flavor number will always match the sign of the electrical charge for each quark/antiquark. The u, c, and t quarks all carry charge of +2/3, and the d,s, and b quarks all carry charge of -1/3, while the antiparticles of each carries a charge equal in magnitude and opposite in sign.

    There are also six leptons and six antileptons. They also transform as doublets by generation;

    (e/v~e), (mu/v~mu), (tau/v~tau)

    The first generation includes the electron and the electron-neutrino which are eigenstates of isospin (Iz = 1/2). The second generation contains the muon and muon-neutrino, and the third generation contains the tau and tau-neutrino. The second and third generation are not eigenstates of isospin, just as the second and third generations of quarks were not eigenstates of isospin, either. The electron, muon and tau each carry an electric charge of -1, while their antiparticles carry the opposite charge. Neutrinos are electrically neutral.

    The Gauge Bosons are divided into groups corresponding to the forces they mediate. For the weak force, these are the spin triplet members W-, W+, and Z. The charged triplet members interact in a fashion that changes flavor or isospin (hence they must carry charge), while the neutral member interacts only in quark pair annihilation and production. For the electromagnetic force, the photon is the mediating boson, coupling only to charged particles without changing their charge. For the strong force, the gluon is the mediating boson, exchanging color charges between quarks (and thus carrying the color charges themselves). For gravitation there is no known interacting particle, but in theory the graviton may be the mediating boson there. Gravitons should interact with any particle that has mass or energy, in other words all particles, without changing the mass of anything. While all of the other Guage Bosons are spin-1 (vector) particles, the graviton is a spin-2 (tensor) particle, if it exists.

    The Higgs Bosons, which assign mass to particles by creating a vacuum potential with interacting Higgs fields, are H+, H-, and H0. H0 is a scalar particle, and is the base cause for the symmetry breaking of the SU(2)xU(1) electroweak interaction into the U(1) electromagnetic interaction (by assigning mass to Gauge Bosons). The Higgs bosons assign the masses of each of the fundamental particles.

    From the leptons and quarks (which are fermions) we can create all the other matter that we see in existence. On the subatomic level, bound states of a quark and antiquark are called mesons (having integer spin), and bound states of three quarks are called baryons (having half-integer spin). The antiparticles of baryons are antibaryons (three antiquarks), while the antiparticles of mesons are also mesons (some are even identical). The current spectroscopy of mesons contains perhaps 100 known states, while the current spectroscopy of the baryons contains at least the same number so far; both have the potential for an infinite number of combinations of quantum numbers, hence a continuum of ever-increasing energy resonances.
     
    Last edited: Nov 21, 2003
  5. Jan 13, 2004 #4
    Is there any particle which does not have spin and mass or any one of these?
    -benzun
     
  6. Jan 13, 2004 #5
    The only particles that have spin-zero, no angular momentum, no isospin, and hence a total spin of zero only, are the pseudoscalar singlet mesons. These include the eta mesons in the ground state. All of them have masses at or above 547 MeV.

    The only massless particles known so far are the photon and gluon. Both are spin-1 particles. The neutrinos may also be massless, but they have spin-1/2.

    There are no known particles that have spin-zero and are massless.
     
    Last edited: Jan 13, 2004
  7. Jan 14, 2004 #6
  8. Jan 14, 2004 #7

    arivero

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    Gold Member

    Well, if besides looking at charge subspaces you look also to mass subspaces it is easier: you have only four separate sectors: lepton with isospin up, lepton with isospin down, quark with isospin up, quark with isospin down. You can not refine further because the mass eigenvectors are not charge eigenvectors (mixing).

    And you are already accounting here for the antiparticles because they are mass-degenerated with the particles and they appear in the same eigenvector of Dirac equation. Same with helicity.

    So you have basically four matter fields.

    They anticommute very much as differential forms (Clifford and all that), so one could speculate if this is related to dimensionality of space time.

    As for force fields, there are W, Z, photon and gluon. There are 8 gluons, buth there are degenerated in mass.

    Last, you'd have at least one Higgs.
     
    Last edited: Jan 14, 2004
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