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New Particle Throws Monkeywrench in Particle Physics

by Anne Minard on March 18, 2009

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fermilab-collider

The CDF detector, about the size of a 3-story house, weighs about 6,000 tons. Its subsystems record the "debris" emerging from high-energy proton-antiproton collisions. Credit: Fermilab

The hits just keep on coming from Department of Energy’s Fermi National Accelerator Laboratory. So far this month, the lab has announced the discovery of a rare single top quark, and then narrowed the gap — twice, actually — for the mass of the elusive Higgs Boson particle, or “God particle,” thought to give all other particles their mass. 

Now, scientists have detected a new, completely untheorized particle that challenges what physicists thought they knew about how quarks combine to form matter. They’re calling it Y(4140), reflecting its measured mass of 4140 Mega-electron volts. 

“It must be trying to tell us something,” said Jacobo Konigsberg of the University of Florida, a spokesman for Fermilab’s collider detector team. “So far, we’re not sure what that is, but rest assured we’ll keep on listening.”

particles

The Standard Model of elementary particles and forces includes six quarks, which bind together to form composite particles. Credit: Fermilab

 

 

 

 

 

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Matter as we know it comprises building blocks called quarks. Quarks fit together in various well-established ways to build other particles: mesons, made of a quark-antiquark pair, and baryons, made of three quarks. 

But recently, electron-positron colliders at Stanford’s SLAC National Accelerator Laboratory and the Japanese laboratory KEK have revealed examples of composite quark structures — named X and Y particles — that are not the usual mesons and baryons. And now, the Collider Detector at Fermilab (CDF) collaboration has found evidence for the Y(4140) particle.

The Y(4140) particle decays into a pair of other particles, the J/psi and the phi, suggesting to physicists that it might be a composition of charm and anticharm quarks. However, the characteristics of this decay do not fit the conventional expectations for such a make-up. Other possible interpretations beyond a simple quark-antiquark structure are hybrid particles that also contain gluons, or even four-quark combinations.

The Fermilab scientists observed Y(4140) particles in the decay of a much more commonly produced particle containing a bottom quark, called the B+ meson. Sifting through trillions of proton-antiproton collisions from Fermilab’s Tevatron, they identified a small sampling of B+ mesons that decayed in an unexpected pattern. Further analysis showed that the B+ mesons were decaying into Y(4140).

The Y(4140) particle is the newest member of a family of particles of similar unusual characteristics observed in the last several years by experimenters at Fermilab’s Tevatron as well as at KEK and the SLAC lab, which operates at Stanford through a partnership with the U.S. Department of Energy.

“We congratulate CDF on the first evidence for a new unexpected Y state that decays to J/psi and phi,” said Japanese physicist Masanori Yamauchi, a KEK spokesperson. “This state may be related to the Y(3940) state discovered by Belle and might be another example of an exotic hadron containing charm quarks. We will try to confirm this state in our own Belle data.”

Theoretical physicists are trying to decode the true nature of these exotic combinations of quarks that fall outside our current understanding of mesons and baryons. Meanwhile, experimentalists happily continue to search for more such particles.

“We’re building upon our knowledge piece by piece,” said Fermilab spokesperson Rob Roser, “and with enough pieces, we’ll understand how this puzzle fits together.”

The Y(4140) observation is the subject of an article submitted by CDF to Physical Review Letters this week. Besides announcing Y(4140), the CDF experiment collaboration is presenting more than 40 new results at the Moriond Conference on Quantum Chromodynamics in Europe this week, including the discovery of electroweak top-quark production and a new limit on the Higgs boson, in concert with experimenters from Fermilab’s DZero collaboration. 

Source: Fermilab

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  • Eric

    Geokstr: “My favorite statistic of all time is this – over 99.999% of all the scientists that have ever lived in the entire history of the human race…ARE STILL ALIVE.”
    ————–

    And I’ll bet most of them would like to keep it that way. :)

  • Peter

    So what does this say about the abilities of the CERN? 3 story house versus 27 kilometre mega tunnel. There’s got to be a quantum increase in intel if we get that going!

  • http://db48x.net/ db48x

    Peter: the “3-story house” figure is only the size of that particular detector. Fermi lab’s Tevatron uses a giant tunnel as well, since the particles are accelerated in the tunnel before being sent to the detector. Of course, the Tevatron’s tunnel is only 7km across. The radius of the tunnel limits the maximum energy of the beam, so the LHC will have quite an edge. Obviously Fermi’s accelerator isn’t obsolete yet, however.

  • Fry

    “http://www.extinctionshift.com/SignificantFindings.htm”

    A bad article by a would-be scientist. He gives 2 formulas for 2 different angles — and note that 2nd formula is derived from 1st and some simple geometry — and argues that this disproves general relativity.
    What a tool!

  • J.L.Lee

    The Fermilab elementary particles chart is beginning to look like a Rubik’s cube.

  • http://aphyr.com Aphyr

    Re: dark matter’s existence: I’m not an astrophysicist, but I’ve played with our radio telescope a bit, and I can inform you that it is relatively easy to reproduce the suggestive evidence that led to the proposal of dark matter. Put simply, if you examine the angular velocity of various stars at different distances from the galactic center (specifically, by looking for the doppler shift in known stellar emission lines), you can construct something called the galactic rotation curve, which is a plot of the angular velocity of the galaxy as a function of radius. If our understanding of gravity is correct, and the galaxy’s density distribution matches what we can see, you’d expect stars to rotate fastest at the center and slower towards the outside. However, this is not the case–the galactic rotation curve is basically flat.

    Some people have proposed a model called MOND, for modified newtonian dynamics, which imposes a phenomenological corrective term on all forces at large distances; this really only means gravity, since the other forces are negligible at astronomical scales. You can get acceptable results using MOND, but it doesn’t sit well with many physicists, because we don’t have a very good reason to impose that corrective term.

    Another explanation is to posit a different mass density for the galaxy–or the addition of “dark matter”. As it turns out, there are several candidates for what this dark matter is; for example, Weakly Interacting Massive Particles, or MAssive Compact Halo Objects are two current (and very interesting) research efforts. Neutrinos are also present in abundance throughout the universe, and can actually account for part–but not all–of the required dark matter mass. Some supersymmetric theories propose additional particles which could account for the remainder… people throw about terms like “neutralino”… but that’s about the edge of my understanding. :-)

    Hope this helps!

  • solrey

    Anthony Peratt produced an accurate spiral galaxy rotation curve based on electromagnetic forces only.
    That’s an explanation that does not require making stuff up.
    Remember, ‘dark matter’ was conjured in order to provide enough galactic mass because the original prediction did not even come close to matching observations.
    Recently, after more accurate velocity measurements, they determined that the Milky Way needs to be 50% more massive than previously thought. And even then it still takes mathematical acrobatics and fanciful names, akin to collateralized debt obligations :) , to produce a flat rotation curve.

    It comes down to faith in un-observed, theoretical mathematical constructs, or confidence in predictable, scalable applications of laboratory confirmed, empirical data.

    peace

  • Lawrence B. Crowell

    The Y(4140) is an odd composite particle of quarks. This does not shake QCD and standard model in fundamental ways, but it does indicate there are hadronic systems which heretofore were unknown.

    Dark matter is a moniker for sme source of gravity which accounts for the motion of stars in galaxies. Galaxies rotate much as a solid disk. Using Gauss’ law you can demonstrate this means that much of the source of gravitation is in halos and something which contains the galaxy. Further, this is not accounted from by an accounting of luminous matter, such as stars, nebula and local clusters.

    This physics of galactic motion is gravitational, it is not electromagnetic. Further, by being “dark” this means what ever it is that makes up this mass does not absorb or emit photons. So EM appears not to play any role in the structure of this mass-energy.

    The neutralino is a condensate of the supersymmetric pairs of the neutrino, photon and Higgs. It is a particle state that exist by physics similar to what happens with kaon oscillations.

    I am not sure how it is that so many people have gotten these ideas about plasma & EM cosmology as some alternative to gravitation and relativity. Please folks, this stuff is nonsense.

    Lawrence B. Crowell

  • Jon Hanford

    @ Lawrence B.. Crowell, What a breath of fresh air compared to some of the numerous dubious postings. Thanks for giving a informed overview of this subatomic particle & where it may fit within the Standard Model. Unexpected discovery’s like this one stoke the flames of particle physicists everywhere. These results are telling us something important, and just maybe the Standard Model will have to be expanded or improved to make way for this new discovery. Double thanks for rebutting pseudoscience notions like PU/ EU/ EC originating from trolls with an agenda. Ever notice that they all provide links to the same web pages to back up their dubious claims. I’m afraid some novices may visit the homemade sights and come away with the idea that these spectacular assertions are in line with current astrophysical thinking. Hopefully most discerning reader will see these sites for what they are; PURE BUNK!

  • John Barrett

    You mean they didn’t find icy tentacles streaching across space sending messages to everything at some sort of a action at a distance? Lame, figures they would just find some new quark. They haven’t found the higgs but they haven’t made a black hole yet either. I know this because if they did we would all be dead. But maybe we could find the higgs and study it for a micro secound before the force of gravity sucks in everything around it. I am still waiting for a proof of the speed of gravity and that random particle pairs are destined to always appear 100% percent of the time near micro scopic places before everything else does. Particle pair creations are measured in square meters and feet!

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