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Science

First Particle Comprising Four Quarks Discovered 111

Posted by Soulskill 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)."
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First Particle Comprising Four Quarks Discovered More

First Particle Comprising Four Quarks Discovered

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  • Yahoo! (Score:5, Funny)

    by musth ( 901919 ) on Tuesday June 18, 2013 @01:51PM (#44041443)

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

  • The Gillette Co. says (Score:5, Funny)

    by Anonymous Coward on Tuesday June 18, 2013 @01:58PM (#44041501)

    Fuck everything, we're doing five quarks.

  • Continues to confirm current theories (Score:5, Interesting)

    by jfdavis668 ( 1414919 ) on Tuesday June 18, 2013 @01:59PM (#44041513)
    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.

    • So someone already knows all this stuff and is just playing the "i told you so" game right!

    • Re:Continues to confirm current theories (Score:5, Informative)

      by lgw ( 121541 ) on Tuesday June 18, 2013 @02:08PM (#44041611) Journal

      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).

      • Re:Continues to confirm current theories (Score:4, Interesting)

        by QilessQi ( 2044624 ) on Tuesday June 18, 2013 @02:26PM (#44041771)

        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.

      • Free parameters not the issue: SM is wrong! (Score:5, Insightful)

        by Roger W Moore ( 538166 ) on Tuesday June 18, 2013 @03:46PM (#44042555) Journal

        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!

        • Re: (Score:2)

          by lgw ( 121541 )

          I've yet to really understand the Higgs mechanism - does it explain why binding energy has/is inertia? I think it would be pretty unsurprising at this point if we one day get a good theory of "more elementary" particles than the standard model, in which all mass is binding energy. Point particle mass seems like the odd exception now. But how do all these different kinds of binding energy each give rise to mass/inertia? Does every field couple to the Higgs field in some way? It just seems very strange.

          • Re: (Score:2)

            by slew ( 2918 )

            As a non-physicist, my understanding of the Higgs mechanism is pretty weak, but...

            The way I understand it the generic idea of the Higgs mechanism isn't simply restricted to be a "mass-generating" mechanism, although the most interesting Higgs mechanism that are searched for are the ones that can suggest electro-weak symmetry breaking which gives non-zero rest masses to W and Z bosons. The reason why most folks are searching for something that can describe this is that W and Z boson have the largest masses

      • 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

        • 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...

          • Well they did not really escaped my memory and I can add a precision to your precision: the weak interaction bosons are W+, W- and Z.

            But are are gauge bosons fundamental particles? They are not used to build compound particles, this is why I did skip them.

            • But are are gauge bosons fundamental particles?

              Yes, they are considered fundamental/"elementary" by the same logic that the others are: that they are not themselves built of other fundamental particles.

    • 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.

      It could just be that, particularly when dealing with particle physics, one can only find what one is looking for. Or put differently, you are unlikely to discover something that the theories don't predict, because all of the equipment and tests have been designed to confirm what the theories predict. Of course that is how the scientific method is supposed to work. You come up with a hypothesis, you devise and experiment to test that hypothesis, you repeat it numerous times to confirm the results.

      In short,

    • I've never quite been comfortable with the idea that we should be disappointed with detailed confirmation of the standard model. Yes there's obviously a more fundamental theory at work that we don't understand yet, but there's no reason that it has to be visible at human-accessible energy scales when the natural (Planck) energy scale of the universe is 16 orders of magnitude larger than the collision energy of the LHC. It's easy to theorize new physics at those energies, but when you don't see anything that

  • LOL .... (Score:5, Funny)

    by gstoddart ( 321705 ) on Tuesday June 18, 2013 @02:05PM (#44041579) Homepage

    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.

    • Re: (Score:2, Informative)

      by Anonymous Coward

      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.

    • Re:LOL .... (Score:5, Informative)

      by Anonymous Coward on Tuesday June 18, 2013 @02:44PM (#44041931)

      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.

      • 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".

    • Let's try a car analogy.

      Quarks are like cars. When an accident occurs with a Ford Pinto, a Barbie Convertible (with Ken), and a D-9 Cat g and they lock bumpers, they merge and you end up with a Subaru Legacy Outback.

      See, quarks can make sense in the real world too! Well, at least as much sense as they normally do.

    • Well, first of all, it's two quarks and two anti-quarks. Second, you'll note that that's the same as two mesons glued together (each with one quark and one anti-quark). And as the original article states, there is controversy about whether in fact this is a new type of particle... or just two mesons. "One side proposes that the particle is actually a union of two ordinary particles called mesons .... Other theorists have tentatively labelled the new particle a true tetraquark — four quarks stuck toge

      • Thank you, I believe I actually followed that.

        So if it's a union of two mesons, I'm calling it a mesonicule, but I'm hoping for tetraquark, because that just sounds awesome and makes we want to say "10 quatloos on the newcomer". ;-)

  • Can five blades [wikipedia.org] be far behind?

  • Fractional charges? (Score:1)

    by Anonymous Coward

    Would particles like this have fractional electrical charges? +4/3, -4/3, etc?

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

    • Would particles like this have fractional electrical charges? +4/3, -4/3, etc?

      No. The "tetraquarks" that are being talked about in this article consist of a pair of quarks and a pair of antiquarks. (i.e., the same quark content as two mesons). Quarks have charges of +2/3 or -1/3, while anti-quarks have charges of -2/3 or +1/3. Whenever you put together 2 quarks with 2 anti-quarks, you'll always get whole number charges, i.e. -2, -1, 0, 1, or 2. (Try it.)

  • Hang on (Score:5, Informative)

    by newsman220 ( 1928648 ) on Tuesday June 18, 2013 @02:26PM (#44041777)
    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.

    • There's no real way to "confirm" the number of quarks. Quark number is not a conserved quantum number, so every particle exists as a superposition of different quark numbers. This is particularly problematic if you probe a particle at very high energies; at sufficiently high energies, every hadron (including the humble proton) appears to be a soup of quark-antiquark pairs bubbling out of the vacuum. However, you should be able to make predictions of what the particle's properties will be if it's mostly like

  • Wow! A quad-quark particle. That must be as exciting for Physicists, as the quad-screwdriver drink I discovered years ago. (or at least I was told I was very happy).

  • Physicists have resurrected a particle that may have existed in the first hot moments after the Big Bang

    I'm pretty certain that these particles do appear every now and then, given how the universe itself acts like a giant particle accelerator - like a much larger, much more powerful, and much much more badass particle accelerator, to be more specific.

  • "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 [finwake.com]

    Four quarks screw up Murray Gell-Mann’s perfect “allusion [takeourword.com]”.

    • Re: (Score:3)

      by ssam ( 2723487 )

      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

      • It’s “Three quarks for Muster Mark!” That’s the allusion I referenced; wasn’t trying to exclude mesons [gsu.edu] or any other quark combinations, including pentaquarks [gsu.edu].

    • Four quarks screw up Murray Gell-Mann’s perfect “allusion [takeourword.com]”.

      Comic Sans screws up Murray Gell-Mann's perfect allusion. My eyes!

  • As long as my car still gets 40 rods to the hogshead then that's the way I likes it.

  • ...still don't know her last name...

  • How many quarks do you see? There....Are.....Four.......Quarks......

  • ...Deep Space Nine?

  • Seriously, they keep changing this since I was in high school and I'm only freaking 25. Last I heard, protons and neutrons were each made up of 3 quarks, not were quarks themselves. What gives?

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