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First Particle Comprising Four Quarks Discovered

Posted by Soulskill on from the odo-is-going-to-be-busy dept.

ananyo writes "Physicists have resurrected a particle that may have existed in the first hot moments after the Big Bang. Arcanely called Zc(3900), it is the first confirmed particle made of four quarks, the building blocks of much of the Universe's matter (abstract one, abstract two). Until now, observed particles made of quarks have contained only three quarks (such as protons and neutrons) or two quarks (such as the pions and kaons found in cosmic rays)."

25 of 111 comments (clear)

  1. Yahoo! by musth · · Score: 5, Funny

    I always vowed to open a tall cool one on the day they found a four-quarker.

  2. The Gillette Co. says by Anonymous Coward · · Score: 5, Funny

    Fuck everything, we're doing five quarks.

    1. Re:The Gillette Co. says by stewsters · · Score: 2, Informative

      Obligatory onion: http://www.theonion.com/articles/fuck-everything-were-doing-five-blades,11056/

    2. Re:The Gillette Co. says by Teresita · · Score: 4, Funny

      Fuck everything, we're doing five quarks.

      And Gillette will get promptly their ass sued by Apple who has already patented the "look and feel" of particles comprised of more than three quarks.

    3. Re:The Gillette Co. says by su5so10 · · Score: 2

      No way. Apple is a resolutely one-button, one-quark company. Let other companies worry about left quarks, right quarks, middle quarks. up quarks, down quarks...

  3. Continues to confirm current theories by jfdavis668 · · Score: 5, Interesting

    It is amazing that these experiments continue to confirm current theories. I was hoping they would find some strange thing that didn't fit, so we could understand why current theories don't explain everything. Maybe next time.

    1. Re:Continues to confirm current theories by lgw · · Score: 5, Informative

      That's been that state of particle physics for decades. I don't think anyone likes the Standard Model, it's inelegant and has more "elementary" particles than can be easily memorized, but it keeps making accurate predictions. Attempts of think of a simpler model from which one could deduce all the details of the standard model have all failed so far in making better predictions (and in the case of String Theory, turned out to be vastly more complex than what they were trying to simplify).

      --
      Socialism: a lie told by totalitarians and believed by fools.
    2. Re:Continues to confirm current theories by QilessQi · · Score: 3, Interesting

      Well said. But if the various numbers that make up the SM are axiomatic, it's interesting to consider what the universe might look like if some (or all) of those axioms were changed. Sort of like considering what Euclidean geometry would look like if the parallel postulate were not true, and consequently coming up with spherical and hyperbolic geometry.

      After all, there's nothing to say that "other" Universes have to work the same way as ours -- even the mechanics of universe formation might be different.

      --
      Koans and fables for the software engineer
    3. Re:Continues to confirm current theories by wonkey_monkey · · Score: 5, Informative

      You might be interested in Greg Egan's Orthogonal series, set in a universe where time is a space-like dimension. He puts plenty of further reading on his website as well.

      --
      systemd is Roko's Basilisk.
    4. Re:Continues to confirm current theories by OakDragon · · Score: 3, Funny

      The physics is cool, but I'm just excited that someone on the Internet used comprise correctly!

      Naturally - they didn't want to comprise their principals!

      --
      Dark Reflection
    5. Re:Continues to confirm current theories by manu0601 · · Score: 2

      That's been that state of particle physics for decades. I don't think anyone likes the Standard Model, it's inelegant and has more "elementary" particles than can be easily memorized,

      You have poor memory :-)

      • 6 quarks (up, down, charm, strange, top, bottom) and their anti particules
      • 3 leptons (electron, muon, tau), their 3 associated neutrinos, and their anti particules
    6. Re:Continues to confirm current theories by femtobyte · · Score: 2

      Plus the gauge bosons (photon, gluons, W, Z), and the Higgs, which seem to have escaped your memory. Apparently, the Standard Model particles are a bit harder to memorize than you think...

  4. LOL .... by gstoddart · · Score: 5, Funny

    There ... are ... 4 ... quarks!

    And, kidding aside, anyone care to put a meaning for this into layman's terms? Is more quarks == more energetic?

    I'm afraid these particles have always been a little too abstract to grok what this means.

    --
    Lost at C:>. Found at C.
    1. Re:LOL .... by Anonymous Coward · · Score: 2, Informative

      The layman's answer is that it has no meaning. If you follow the link, it shows a pretty picture about quark arrangements, only the 'Baryonic' section matters at all to a layman, and most baryonic matter still doesn't matter.

      For an interested layman, it just means 'these Legos can click together in more ways than we have recorded.'

      For any more depth than that, you don't count as a layman anymore, so go read the root papers.

    2. Re:LOL .... by Anonymous Coward · · Score: 5, Informative

      anyone care to put a meaning for this into layman's terms?

      To my mind the issue is color balance. No, really. Quarks have a property called "color" (not in any way related to visible colors), which needs to be balanced in order to get a stable particle. (It's a consequence of the non-abelian SU(3) gauge group of the strong nuclear force. Aren't you glad you asked?)

      The upshot is that to get a stable particle, you need to have a set of blue+anti-blue, or red+anti-red, or green+anti-green, or blue+green+red or anti-blue+anti-green+anti-red quarks. This is the origin of the 2 quark (color+anti-color) or 3 quark (all colors) particle. (Of course, this is a simplification - because of gluons the colors of the particles are constantly swapping around, but in ways that maintain the color balance.)

      Having four quarks upsets this notion. You need some way of balancing the color, and the "traditional" ways of doing it won't work. My guess is that this new particle is probably something like a blue+anti-blue+red+anti-red. As the news article mentions, it's apparently still up in the air whether this should really be considered a true four quark particle, or simply two particles (blue+anti-blue & red+anti-red) in very close association.

    3. Re:LOL .... by BitterOak · · Score: 2

      No one is suggesting that this is not a colorless state. It consists, as you suggest, of two quarks and two anti-quarks in a colorless configuration. If it is truly a new state, it should have a different mass than two mesons "stuck together".

      --
      If I can be modded down for being a troll, can I be modded up for being an orc, or a balrog?
  5. Hang on by newsman220 · · Score: 5, Informative

    When I read the article yesterday they had not confirmed 4 quarks. They suspected four quarks, but it could also be a pair of two-quark particles closely bonded in a hadron molecule. Confirmation was hoped for in a year or so.

  6. Re:Fractional charges? by Relic+of+the+Future · · Score: 2

    Two quarks (-1/3 or +2/3) and two anti-quarks (+1/3 or -2/3) so no, sum is always an integer.

    --
    Those who fail to understand communication protocols, are doomed to repeat them over port 80.
  7. Three quarks for Muster Mark! by kstahmer · · Score: 2

    "Three quarks for Muster Mark!
    Sure he hasn't got much of a bark
    And sure any he has it's all beside the mark."

    -- James Joyce, Finnegans Wake

    Four quarks screw up Murray Gell-Mann’s perfect “allusion”.

    --
    HRH The Duke of Windsor
    1. Re:Three quarks for Muster Mark! by ssam · · Score: 2

      not really. there are 6 types of quark (plus 6 anti quarks). before we had only observed them bound 2-quark and bound 3-quark states, (though there have been several claimed 5-quark observations that have not stood up). Now we have 2 groups claiming to see a 4-quark state

  8. Pentaquark by Roger+W+Moore · · Score: 2

    Already been theorised and some experiments claimed to see them a while ago until they fixed their analysis. I'd personally hold out a bit longer before believing in tetraquarks - this is by no means the first claim to observe them and QCD spectroscopy is notoriously hard from both an experimental and theoretical point of view.

  9. Free parameters not the issue: SM is wrong! by Roger+W+Moore · · Score: 5, Insightful

    I don't think anyone likes the Standard Model, it's inelegant and has more "elementary" particles than can be easily memorized, but it keeps making accurate predictions.

    Actually that is not really true: just about anyone can do a very simple experiment which is inconsistent with the predictions of the Standard Model. Pick up an object and then let it go. There is nothing in the Standard Model which will predict the behaviour you observe. That's why we physicists don't like it. Parts of it are extremely elegant - e.g. the Higgs mechanism - but since it can't explain gravity we know it is wrong and yet we still cannot find any better model that works for all the other fundamental forces and gravity...not to mention explaining other phenomena like Dark Matter, matter/anti-matter asymmetry of the universe, baryon number violation... etc. The number of particles and free parameters is a minor issue!

    1. Re:Free parameters not the issue: SM is wrong! by femtobyte · · Score: 5, Informative

      Gravitons are not a Standard Model particle, though you can tack them on to the Standard Model to partially explain some gravitational behavior (though not without introducing mathematical problems). The link between Standard Model (and variants) field theories and General Relativity is still missing: one can calculate how particles act within gravitationally bent spacetime, but there is no "microscopic" model for how particles themselves bend the spacetime around them as you approach high enough energies for that to be relevant.

  10. 4.5 litres. Hic. by Hognoxious · · Score: 4, Funny

    Four quarks? That's a Galuon, isn't it?

    --
    Confucius say, "Find worm in apple - bad. Find half a worm - worse."
  11. SM precludes gravity like SR precludes FTL travel by Roger+W+Moore · · Score: 2

    The Standard Model doesn't preclude gravity

    That is like arguing that special relativity does not preclude faster than light travel. You cannot add FTL travel to SR without inconsistencies (like breaking causality) but you technically can add it. You could also imagine developing a framework which expanded on SR and allowed FTL velocities. In the same way adding gravity to the Standard Model creates inconsistencies (renormalization cut-off) but you can imagine a framework which expands on the SM and somehow incorporates gravity.

    The only difference between these two is that gravity is a phenomenon that clearly exists whereas FTL does not (as far as we know). Hence we say the SR forbids FTL because we have no way to incorporate FTL and we do not see it. In the same way the SM forbids gravity: it leads to inconsistencies in the theory just like FTL does in SR. However since gravity clearly exists we conclude that the SM is wrong not that gravity is forbidden!