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LHCb Confirms Existence of Exotic Hadrons 99

Posted by Soulskill
from the pushing-back-the-boundaries-of-physics dept.
An anonymous reader sends this news from CERN: "The Large Hadron Collider beauty (LHCb) collaboration today announced results that confirm the existence of exotic hadrons – a type of matter that cannot be classified within the traditional quark model. Hadrons are subatomic particles that can take part in the strong interaction – the force that binds protons inside the nuclei of atoms. Physicists have theorized since the 1960s, and ample experimental evidence since has confirmed, that hadrons are made up of quarks and antiquarks that determine their properties. A subset of hadrons, called mesons, is formed from quark-antiquark pairs, while the rest – baryons – are made up of three quarks. ... The Belle Collaboration reported the first evidence for the Z(4430) in 2008. They found a tantalizing peak in the mass distribution of particles that result from the decays of B mesons. Belle later confirmed the existence of the Z(4430) with a significance of 5.2 sigma on the scale that particle physicists use to describe the certainty of a result. LHCb reports a more detailed measurement of the Z(4430) that confirms that it is unambiguously a particle, and a long-sought exotic hadron at that. They analyzed more than 25,000 decays of B mesons selected from data from 180 trillion (180x10^12) proton-proton collisions in the Large Hadron Collider."
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LHCb Confirms Existence of Exotic Hadrons

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  • by barlevg (2111272) on Wednesday April 09, 2014 @01:51PM (#46707029)
  • strange (Score:2, Interesting)

    by slashmydots (2189826)
    If it's not made up of quarks, what evidence so they have that it actually is a Hadron at all? They just stated that the definition of a Hadron is a particle made up of quarks.
    • Re:strange (Score:5, Informative)

      by iggymanz (596061) on Wednesday April 09, 2014 @02:22PM (#46707365)

      it is believe to be made of quarks, but instead of the usual two or three it has four, c c_ d u_

      that means it has charge of negative one

    • Re:strange (Score:5, Informative)

      by gman003 (1693318) on Wednesday April 09, 2014 @02:22PM (#46707373)

      It *is* made up of quarks - a charm quark, an anti-charm quark, down quark, and anti-up quark. The interesting thing is that this is a pairing never before seen - all previous hadrons were either two quarks (quark + antiquark of same color) or three quarks (three quarks or antiquarks, all of different colors). Two quarks and two antiquarks has been postulated but never observed, until now.

      • Re:strange (Score:4, Informative)

        by Anonymous Coward on Wednesday April 09, 2014 @06:04PM (#46709217)

        For a more useful perspective and pretty graph of the experimental data, see:
        http://www.quantumdiaries.org/2014/04/09/major-harvest-of-four-leaf-clover

    • It is made of quarks, it's "just" that it doesn't seem to be a meson (quark +antiquark) or a baryon (3 quarks)

      They're speculating that it's charm + anticharm + up + antidown, i.e 4 quarks (or 2 quark/antiquark pairs).

      Probably bollocks.

      • Re:strange (Score:5, Informative)

        by Anonymous Coward on Wednesday April 09, 2014 @03:18PM (#46707905)

        To get Psi' you need c-cbar; to get a pi you need an up and a down. The final state they observe is a mu-,mu+ K pi. The production of the muons in pairs means that they came out of the same reaction -- that is you can put them together to get a Psi' with good reliability. So you that leaves you with Psi' k and pi, you could have an initial state that decays to a psi' and a (k+pi) in a baggy (aka the K* resonances), or a psi' and a k and a pi that don't interact with each other (but three prong decays are well down from pair wise decay chains), or a k + (psi' pi) in a baggy. Since momentum and energy are conserved having K*'s in the produced stuff can reflect into the other pairings (this is the crux of the venerable Dalitz plot analysis). The reflections are insufficient to explain away a k +(psi' pi) decay chain --it's not an echo from other known physics. The psi' is a pure ccbar state and the quark content of the pion is well known -- either all four quarks are present in the (psi' pi) baggy or something really weird is going on. Whip out the Occam's razor and you claim a tetraquark. (It's not clear however that the ancient a0(980) and f0(980) are not tetraquarks or molecules ... it's just a very very hard place to work -- here the muon decays help a lot at cleaning up the states -- there's not a great analog of the psi' below 1GeV that is a clean resonance to beat against.

    • No, it defines hadrons as follows: "Hadrons are subatomic particles that can take part in the strong interaction – the force that binds protons inside the nuclei of atoms." It then goes on to say that Hadrons are theorized to be constituted by quarks. Presumably the evidence they have for these particles being hadrons is that they take part in the strong interaction.

    • It's not made up of Quark's, it's made up of Rom's.

  • It's not a quark-antiquark pair. It's not three quarks of different colors. So what is it? Four quarks? Something else?

    • by MobyDisk (75490) on Wednesday April 09, 2014 @02:13PM (#46707273) Homepage

      According to http://lhcb-public.web.cern.ch... [web.cern.ch]
      "It is therefore a four quark state or a two-quark plus two-antiquark state."

    • Exactly what I was just about to ask.

      hadrons are made up of quarks and antiquarks that determine their properties. A subset of hadrons, called mesons, is formed from quark-antiquark pairs, while the rest – baryons – are made up of three quarks.

      And the exotic hadrons...?

      This "summary" appears to be simply paragraphs 1, 2, 4 and 5 from the article, with the submitter's sole contribution being to delete paragraph 3, which gives us the pertinent information that:

      But since it was first proposed physicists have found several particles that do not fit into this model of hadron structure. Now the LHCb collaboration has published an unambiguous observation of an exotic particle – the Z(4430) – that does not fit the quark model.

      So, that explains that.

      http://en.wikipedia.org/wiki/E... [wikipedia.org]

    • by hamburger lady (218108) on Wednesday April 09, 2014 @03:09PM (#46707815)

      Fuck it, we're doing five quarks.

      Would someone tell me how this happened? We were the fucking vanguard of particles in this universe. The meson was the hadron to own. Then the other guy came out with a three-quark nucleon. Were we scared? Hell, no. Because we hit back with a little thing called the proton. That's three quarks and a positive charge. For positivity. But you know what happened next? Shut up, I'm telling you what happened—the bastards went to four quarks. Now we're standing around with our cocks in our hands, selling three quarks and a charge. Charge or no, suddenly we're the chumps. Well, fuck it. We're going to five quarks.

      • by Megane (129182)

        Sure, we could go to four quarks next, like the next universe over. That seems like the logical thing to do. After all, three worked out pretty well, and four is the next number after three. So let's play it safe. Let's make a thicker gluon field and call it the Quark3SuperTurbo. Why innovate when we can follow? Oh, I know why: Because we're a fundamental force of the universe, that's why!

        Now we're standing around with our cocks in our hands

        Such a missed opportunity for the word "hadron".

      • Hmmm....this sounds familiar: http://www.theonion.com/articl... [theonion.com]
      • You never go full hadron.

  • 4 quarks particle (Score:3, Informative)

    by Anonymous Coward on Wednesday April 09, 2014 @02:18PM (#46707329)

    From the original publication ( http://lhcb-public.web.cern.ch/lhcb-public/ ):
    The minimal quark content of the Z(4430) state is: charm + anti-charm + down + anti-up.
    It is therefore a four quark state or a two-quark plus two-antiquark state.

  • by JoshuaZ (1134087) on Wednesday April 09, 2014 @02:19PM (#46707343) Homepage
    Can someone who knows more about this subject explain what if any the implications this result has for the Standard Model?
    • by DirePickle (796986) on Wednesday April 09, 2014 @02:29PM (#46707441)
      Unfortunately, none really. There's nothing in the standard model that says we can't have tetraquarks or mesonic molecules (this seems to be one or the other), it's just that we haven't seen any before.
    • by BitZtream (692029)

      It means we're one step closer to confirming theoretical constructs such as wormholes as we're rapidly approaching the stage where exotic matter is no longer theoretical, and things such as negative mass start to look achievable.

      Not that this observation makes all of that actually true, but we're still moving in the right direction to maybe eventually one day confirm and observe things such as stable wormholes.

      • by Anonymous Coward
        Exotic hadrons have absolutely nothing to do with the "exotic matter" talked about needed for wormholes. It doesn't move us in that direction at all, even though both use the description "exotic" it is such a generic term and these do not have any of the properties, particularly negative mass, that is needed for wormholes. These don't even really challenge the Standard Model, but were already half expected. They only challenge particular approximate calculations based on the Standard Model, which we were
  • Lisi's "An Exceptionally Simple Theory of Everything" predicts particles. Is this one of those particles that it predicts?

    http://en.wikipedia.org/wiki/A... [wikipedia.org]

    • by iggymanz (596061)

      Lisi's theory predicts fields and the kind of particles known as bosons, it's a field theory that hasn't even been refined enough to include quantization. It doesn't predict mass of particles either.

  • by Anonymous Coward on Wednesday April 09, 2014 @02:22PM (#46707363)

    18 comments in, and 17 of them are just stupid stuff about hard-ons. Either Slashdot has been taken over by 12 year old boys, or they're all just still boys trapped in the bodies of men.

    • by mx_mx_mx (1625481)

      Nope.. we all moved to http://soylentnews.org/ [soylentnews.org]

    • by wjcofkc (964165) on Wednesday April 09, 2014 @02:33PM (#46707471)
      Clearly you weren't here in those dark days before moderation. Natalie Portman, hot grits, goatse links, etc, etc, etc... Don't like what you see in the comments? Get an account, stop whining as an AC, earn some mod points, and help eradicate the less flattering posts. I do.
    • Of course, in every high-energy experiment, there's a lot of juvenile, short-lived resonances, but only few respectable, long-lived stable particles like us.
    • by steelfood (895457)

      Don't kid yourself. "Men" in the form you romanticize do not exist. All men are "boys" at heart, and remain so irrespective of age.

      There's a reason why male-oriented comedy is filled with penis jokes. They're not just targeting the teenage demographic.

    • For slightly less purile fun, look at https://www.youtube.com/watch?... [youtube.com] (The large haddock collider)

  • by MAXOMENOS (9802) <maxomai.gmail@com> on Wednesday April 09, 2014 @02:23PM (#46707375) Homepage

    Belle later confirmed the existence of the Z(4430) with a significance of 5.2 sigma on the scale that particle physicists use to describe the certainty of a result.

    I believe that "scale" is called the normal distribution; that is to say, the odds of getting that result as a fluke are the same as finding a point 5.2 standard deviations away from the mean of the normal curve. If so, everything in that sentence after "5.2 sigma" can be left out.

    • by Kjella (173770)

      Well, to a lay person it might sound a little like "Belle later confirmed the existence of the Z(4430) with [something]", common folk don't talk about probability in terms of "a significance of 5.2 sigma".

      A better phrasing would be:
      Belle later confirmed the existence of the Z(4430) with a significance of 5.2 sigma, a certainty high enough to be considered a discovery in particle physics.

  • Since I could no longer comprehend the technical nature of the discovery, what is the consequence of this discovery? Will existing theories be changed (or validated)? Any complications to other theories?

    I hope someone with more knowledge in the subject matter will be able to share.

    • by Xtifr (1323)

      what is the consequence of this discovery?

      Some idle speculation has finally been confirmed.

      Will existing theories be changed (or validated)?

      Not really. There was no particular reason to think this was impossible. We just didn't have any evidence it was possible.

      Any complications to other theories?

      Not to any useful theories. Theories like the Electric Universe have one more thing added to the list of things they can't explain, but that's no surprise. :)

  • ... er, I thought it was a typo that was to read, "LHCb Confirms Existence of Exotic Hard on's"

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