Image: Tevatron at Fermilab
An aerial photo of Fermilab shows the futuristic Wilson Hall alongside the cooling canal for the Tevatron, with a prairie habitat inside the collider ring. staff and news service reports
updated 7/27/2011 6:57:34 PM ET 2011-07-27T22:57:34

U.S. scientists said on Wednesday that they could get enough data by the end of September to establish whether the Higgs boson, long believed to have played a vital role in the creation of the universe, exists or not.

Physicist Eric James from Fermilab near Chicago told a conference in the French city of Grenoble that his team — working in parallel with scientists at the CERN research lab near Geneva — were fast narrowing down the mass range where the particle could be hiding.

The Higgs boson is the last missing piece of the so-called Standard Model of physics. It's thought to be the particle that gave mass to the debris of the big bang 13.7 billion years ago, but it hasn't yet been detected.

Teams at CERN's Large Hadron Collider and Fermilab's Tevatron have been looking for the boson's trail in the products of trillions of high-energy particle collisions.

CERN Director-General Rolf Heuer told the Grenoble meeting of top international physicists on Monday that the Higgs had so far evaded researchers at the Large Hadron Collider. He said the LHC could "settle the question" of the Higgs' existence by the end of 2012.

The U.S. research center put up a much tighter timetable.

Fermilab Today, the laboratory's daily bulletin, said James reported in Grenoble that researchers at the Tevatron, the LHC's friendly rival, were stepping up their experiments in the search for the Higgs.

They were now "extremely close to the sensitivity needed ... either to see a substantial excess of Higgs-like events or to rule out the existence of the particle," the bulletin declared in a summary of James' report.

Earlier studies at the Tevatron, in operation since 1983, and at the much bigger LHC, operating since March 2010, have left a narrow window as the best place to look for the Higgs, posited by British scientist Peter Higgs and others four decades ago.

The experiments in Tevatron, Fermilab said, "are on track to collect enough data by the end of September 2011 to close this window if the Higgs particle does not exist." The Tevatron is due to shut down at the end of September, and a U.S. replacement is not in view. Rather, the LHC will monopolize the spotlight for particle physics research.

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Although the required data could be taken in by the end of September, it would take months more to analyze the data.

Last weekend, scientists visiting Grenoble for the Europhysics Conference on High-Energy Physics said they were encouraged by reports from CERN and Fermilab showing that the Higgs might be emerging from hiding.

Physicists said unusual fluctuations in the data from the explosions suggested that they were getting close to the Higgs in the mass range of 120 billion to 150 billion electron volts, or 120 to 150 GeV. But others cautioned that these could be misreadings or random anomalies.

“With the additional data and further improvements in our analysis tools, we expect to be sensitive to the Higgs particle for the entire mass range that has not yet been excluded," Dmitri Denisov, co-spokesperson for the Tevatron's DZero experiment, said in the Fermilab report. "We should be able to exclude the Higgs particle or see first hints of its existence in early 2012.”

Higgs, who is tipped to get a Nobel prize if his theory is proven correct and the particle is identified, has always left open the possibility that he might be wrong. "If it doesn't exist, there must be something else like it," he once said.

This report includes information from Reuters and

© 2013

Interactive: Inside the big bang machine

Explainer: What’s a hadron? Tour the particle zoo

  • Image: Elementary particles

    The Standard Model of particle physics is one of science's most successful theories, enabling the development of devices ranging from light bulbs, to microwave ovens and television, to quantum computing devices. The Standard Model is also one of the oddest theories, because it lays out a dizzying menagerie of hundreds of subatomic particles. At its heart are 16 types of elementary particles ... plus at least one more mysterious particle that scientists are spending billions of dollars to detect.

    Click on "Next" to get the full rundown.

  • Quarks

    Image: Quarks and gluons
    Berkeley Lab

    Six "flavors" of quarks have been detected: up and down, charm and strange, top and bottom. Quarks are almost always found in different combinations, bound together by gluons (more on those later). Particles built up from quarks and gluons are called hadrons. The Large Hadron Collider is so named because it's a large collider that smashes hadrons together.

    Three-quark combinations fit in the category of baryons. The best-known baryons are the proton (with two up quarks and one down quark) and the neutron (with two down quarks and one up quark).

    Particles that have one quark and one antiquark fit in the category of mesons. For example, the pion, or pi meson, contains an up quark and an anti-down quark.

  • Leptons

    Image: Single electrons in helium
    Brown University

    Six "flavors" of leptons have been detected: The negatively charged electron is the best-known lepton — along with its antimatter counterpart, the positron. This photo shows the path of single electrons passing through liquid helium, in an experiment devised by Brown University researchers.

    The muon is also negatively charged, but it's about 207 times as massive as the electron. ("Who ordered that?" physicist Isidor Rabi reportedly asked.) The negatively charged tau particle is even bigger — 3,477 times as massive as the electron — but it decays into other particles in less than a trillionth of a second.

    Each of those leptons has a neutrino associated with it: the electron neutrino, the muon neutrino and the tau neutrino. Neutrinos interact only weakly with other particles, and they zip through our planet virtually without a trace. Physicists only recently determined that they have mass, but there's still a great deal of mystery surrounding the ghostly particles.

  • Force carriers

    Image: Graviton

    The Standard Model sets aside a category for particles that are associated with force fields. The effect of a field can be viewed as involving an exchange of such force-carrying particles.

    Four elementary force-carrying particles have been detected. The best-known force carrier is the photon — which plays a part in the electromagnetic spectrum, including visible light. The gluon binds quarks together through the strong nuclear force. The weak nuclear force involves the exchange of W and Z bosons. The W boson can carry a positive or a negative charge, while the Z boson is neutral.

    If gravity could be incorporated into the Standard Model, the force-carrying particle would be called the graviton (shown here in an artist's depiction). However, gravitons have not yet been detected, and at least for now, such particles are not accounted for in the Standard Model.

  • Bosons vs. fermions

    Image: Bosons vs. fermions
    Rice Univ. via AIP

    All force-carrying particles are bosons, but not all bosons are force carriers. The difference has to do with a property known as particle spin. Particles with a fractional spin value (for example, electrons, protons and neutrons) are fermions. Two identical fermions cannot occupy the same quantum state. This is a property that keeps electrons from collapsing into a jumble, and thus makes chemical reactions possible.

    All particles with a whole-integer spin value are classified as bosons, and such particles can occupy the same quantum state even if they're identical. The photon is the best-known type of boson.

    Even atoms can be classified as fermions and bosons. This photo shows how atom clouds of lithium-7 (bosons) and lithium-6 (fermions) behave at low temperatures. The bosons collapse into a compact cloud, while the fermions can't squeeze that closely together.

  • The mysterious Higgs

    Image: Higgs as seen by CMS
    Ianna Osborne / CERN / CMS Collection

    The Higgs boson is the only particle predicted by the Standard Model that has not yet been detected. The Higgs is the main quarry for physicists at the Large Hadron Collider. This image is a simulation of the Higgs' signature as it might appear in one of the LHC's detectors.

    The Higgs boson, named after Scottish theorist Peter Higgs, is thought to be associated with a field that endows some particles (such as the weak nuclear force's W and Z bosons) with mass, while leaving the electromagnetic force's photons without mass.

    This Higgs field may have played a role at the very beginnings of the universe: Physicists believe that at the highest energies, the electromagnetic and weak nuclear forces were unified, but something led to "electroweak symmetry breaking" as the infant cosmos cooled. That would be why the electromagnetic force and the weak nuclear force are distinct in the current universe. The Large Hadron Collider could shed new light on this mysterious Higgs mechanism.

  • Why so complicated?

    Image: Particle zoo
    Tim Jones / McDonald Observatory / HETDEX

    Hadrons and leptons? Baryons and mesons? Fermions and bosons? Sometimes it seems as if particle physicists set up these classifications just to keep outsiders totally confused. But for researchers, these occasionally overlapping categories are useful for figuring out how different types of particles interact with each other.

    In a sense, it's as if we've been talking about the game of chess but have gotten only to the point of naming the different pieces on the board: black pieces and white ones, pawns and knights, bishops and rooks, kings and queens. The real meaning of the game comes out when you start studying how the pieces perform and interact.

    To delve into the deeper meaning of the Standard Model, you can visit The Particle Adventure at Lawrence Berkeley National Laboratory, "A Subatomic Venture" at CERN, or Particle Physics UK.


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