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posted by martyb on Sunday July 05 2020, @10:04AM   Printer-friendly
from the Kirk's-quirks-warps-quatro-quarts-quartz-quarks dept.

Exotic never before seen particle discovered at CERN:

The Large Hadron Collider Beauty (LHCb) project has observed an exotic particle made up of four charm quarks for the first time.

[...] Quarks form together to form composite particles known as hadrons, which include protons and neutrons. This breakthrough new discovery can help scientists now understand the complex ways in which quarks bind themselves together to form these composite.

Quarks typically combine together in groups of twos and threes to form hadrons. For decades, however, theorists have predicted the existence of four-quark and five-quark hadrons, which are sometimes described as tetraquarks and pentaquarks and in recent years experiments including the LHCb have confirmed the existence of several of these exotic hadrons.

[...] "Particles made up of four quarks are already exotic, and the one we have just discovered is the first to be made up of four heavy quarks of the same type, specifically two charm quarks and two charm antiquarks," says the outgoing spokesperson of the LHCb collaboration, Giovanni Passaleva. "Up until now, the LHCb and other experiments had only observed tetraquarks with two heavy quarks at most and none with more than two quarks of the same type."

[...] As with previous tetraquark discoveries, it is not completely clear whether the new particle is a "true tetraquark", that is, a system of four quarks tightly bound together, or a pair of two-quark particles weakly bound in a molecule-like structure. Either way, the new tetraquark will help theorists test models of quantum chromodynamics, the theory of the strong interaction.

Journal Reference:
LHCb collaboration, Aaij, R., Beteta, C. Abellán, et al. Observation of structure in the $J/ψ$-pair mass spectrum, (arXiv: 2006.16957)


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  • (Score: 2) by DrkShadow on Sunday July 05 2020, @04:11PM (7 children)

    by DrkShadow (1404) on Sunday July 05 2020, @04:11PM (#1016527)

    Can we even call this a particle? As opposed to four
    Small things happening to be in the same vicinity at the Same time?

    It takes an electron 1.5E-16 seconds to cover the orbit around an electron. (All other physics about "it's not actually an orbit" dont apply, I'm looking for time vs distance) if this "particle" existed for the time it would require an electron to cover one ten-thousandth of the diameter of an electron/proton orbit... aren't we approaching planck length? It feels like any effect such a "particle" could have on its surroundings would be just incidental.

    Anyway, how can a particle and an anti-particle exist in such close proximity without annihilating each other?

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  • (Score: 0) by Anonymous Coward on Sunday July 05 2020, @04:47PM

    by Anonymous Coward on Sunday July 05 2020, @04:47PM (#1016535)

    >> how can a particle and an anti-particle exist in such close proximity without annihilating each other?

    Maybe it takes 10^-21 seconds for them to notice each other.

  • (Score: 2, Informative) by Anonymous Coward on Sunday July 05 2020, @04:52PM (2 children)

    by Anonymous Coward on Sunday July 05 2020, @04:52PM (#1016537)

    You're looking for Planck time, which is 10^-43 seconds, plenty of time for the tetraquark to exist. If the Planck time were analogous to one second, this tetraquark would last a thousand times the age of the universe.

    The tetraquark's existence is meaningful (scientifically, not spiritually, although maybe!) because there is still a strong force interaction which holds the quarks together, however briefly, and determines the resulting decay products.

    • (Score: 0) by Anonymous Coward on Sunday July 05 2020, @08:30PM

      by Anonymous Coward on Sunday July 05 2020, @08:30PM (#1016631)

      Thanks! Please come back and keep posting usefully like this.

    • (Score: 2) by Muad'Dave on Monday July 06 2020, @01:31PM

      by Muad'Dave (1413) on Monday July 06 2020, @01:31PM (#1017011)

      See the relativistic muon experiment [gsu.edu] for an example [wikipedia.org].

  • (Score: 2) by pe1rxq on Sunday July 05 2020, @05:22PM (1 child)

    by pe1rxq (844) on Sunday July 05 2020, @05:22PM (#1016541) Homepage

    You are forgetting relativity. If particles move fast enough space contracts so much that from a human perspective they can get very far and live long.
    This is also yet another reason why your 'electron orbit' refefence is bull.

  • (Score: 2) by Immerman on Monday July 06 2020, @03:49PM

    by Immerman (3985) on Monday July 06 2020, @03:49PM (#1017092)

    Yes, we can.

    It boils down to how particle accelerators work - you smash a few particles into each other at almost light speed, and that immense kinetic energy gets converted to other forms of energy - neutralizing the intense negative binding energy so that sub-particles can fly free, and as well as creating whole new particles from pure energy.

    Much of what you create is unstable, and most of it is also traveling at high speeds, so if for example you're using a bubble chamber you'll see an explosion of particle traces emerging from the initial impact point, and some of those traces then themselves "explode" as the unstable particles decay. You're not going to get to explosion fragments traveling in the exact same direction and then suddenly spontaneously repel each other after they've traveled a bit.

    Even without bubble chamber you can recreate a great deal of what happened because of the rigorous rules of quantum chromodynamics. Quarks can't exist individually, only in particles that have a net color charge of zero. Most commonly you'll see either mesons (quark anti-quark pairs with charges such as red + anti-red = 0) or bosons (normal matter) that are some combination of three charges that adds up to zero (e.g. red+green+blue = 0)

    Also, quarks and anti-quarks don't annihilate - despite the name, they don't behave like matter and antimatter. In fact *all* mesons are composed of quark-antiquark pairs.