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Antimatter’s Oscillations Probed

An operating run at Fermilab involving the Tevatron, the world’s highest-energy particle accelerator, has produced an experimental result of extraordinary precision, one that has measured transitions between matter and antimatter that occur three trillion times a second. Tevatron Run 2, from February of 2002 to January of this year, produced trillions of collisions between protons and antiprotons to achieve the discovery, a measurement sought for two decades.

Making the fast change is the B_s meson (pronounced B-sub-s), whose behavior is predicted by the Standard Model that describes our understanding of fundamental particles and forces in the universe. The finding thus reinforces that model in the world of the exquisitely small. The B_s meson is made up of a bottom quark bound by the strong nuclear interaction to a strange antiquark. These exotic particles, present in abundance in the early universe, can only be produced and studied at particle accelerator installations like Fermilab’s.

Earlier measurements of the matter-antimatter transitions in the B_s meson did not reach the level of accuracy of this latest work, in which the probability for a false observation has been shown to be less than about eight in 100 million. And the discoveries from this impressive run of data may not be over yet:

“Everyone in Fermilab’s Accelerator Division has worked hard to create the number of collisions that were required to reach this impressive result,” said Fermilab Director Pier Oddone. “We’re glad that CDF has been able to put these efforts to such good effect. This is one of the signature measurements for Run II, and as we collect several times the data already on hand, I have great expectations for future discoveries.”

CDF refers to the Collider Detector at Fermilab collaboration, an experiment in high energy particle collisions that involves 700 physicists from 61 institutions in 13 countries. MIT’s Christoph Paus presented the discovery in a talk at Fermilab on Friday September 22; a paper on this work has been submitted to Physical Review Letters.

Centauri Dreams‘ take: The behavior of exotic particles like the quarks under study and their interactions with matter and antimatter may tell us a good deal about how the early universe evolved. It may also push physics into a more complete Standard Model, and that, in turn, should help us understand just how matter and antimatter are entwined. The sense here is that for breakthroughs in antimatter production to occur — and for propulsion purposes we must hope some day they will — they must emerge with the underpinning of work like CDF’s, which may yet tease out phenomena the Standard Model does not predict.

Comments on this entry are closed.

  • Adam September 28, 2006, 7:55

    Perhaps the Tevatron and LHC will show us how to burn baryons without mucking around with antimatter. That would be a far more useful trick.

  • JD September 29, 2006, 19:06


    Out of curiousity has anyone, to your knowledge, ever postulated a theory on that idea? The concept is very, very intrigueing.

    Hmm so it’s assumed anti particles behave the same? Please no redicule but it seems as if matter/antimatter is determined by the frequency of it’s “vibration” (once again please, no redicule, I’m groping for descriptive words, not trying to be precise :)

  • Adam September 30, 2006, 3:28

    Hi JD

    None less than Sakharov himself laid down the requirements for ‘baryon burning’ to take place, and over the years many different asymmetric baryon making and destroying processes have been discussed, but so far they’re all a bit too high energy for direct observation.

    Some process gave the Universe more baryons than anti-baryons and the more we understand about both the more we know about how they might be destroyed asymmetrically. Frank Tipler’s current version of his Omega Point Theory requires a large-scale baryon-number violating field, the sphaleron field, to exist and to be used by intelligent life on a gigantic scale – to consume the Universe’s excess of baryons and to cause the cosmological constant to drop to zero, allowing cosmic recollapse.

    This is a testable prediction and the LHC data might give us some insight into how it happens, if Tipler is right. Or it might show us even more exotic phenomena like large extra-dimensions which should allow black-holes to be made in particle collisions. If that’s discovered then there’s a whole unseen Universe surrounding us in hyperspace, known as ‘the Bulk’, which might have utterly unforeseen properties beyond the Standard Model.

    As for the ‘vibration’ you mention what’s happening in a B_s meson is a quark and anti-quark pair are briefly kept from annihilating due to the ‘colour’ force between them. Otherwise there’s no currently discernible difference between quarks and anti-quarks. Yet there’s still more quarks than anti-quarks in this Universe and that’s where this story began.

  • ljk March 14, 2007, 8:37

    New form of matter-antimatter transformation observed for first time


    Whilst science fiction toys effortlessly with anti-matter, in reality it
    can be very hard to produce, so researchers around the world are
    celebrating a new break through in this area. For the first time,
    scientists using the BaBar experiment at the Stanford Linear Accelerator
    Center (SLAC) have observed the transition of one type of particle, the
    neutral D-meson, into its antimatter particle – a process known as
    ‘mixing’. The new observation will be used as a test of the Standard
    Model, the current theory that best describes the entire universe’s
    luminous matter and its associated forces.

    UK BaBar spokesman, Fergus Wilson of the Rutherford Appleton Lab said
    “D-meson mixing was first predicted over three decades ago but it is
    such an elusive phenomenon that it has taken until today to see it. The
    observation of D-meson mixing is yet another outstanding achievement for
    the BaBar experiment. The BaBar collaboration continues to make
    ground-breaking measurements that challenge our understanding of how
    elementary particles behave.”

    “Achieving the large number of collisions needed to observe D-meson
    mixing is a testament to the tremendous capabilities of the laboratory’s
    accelerator team,” said SLAC Director Jonathan Dorfan. “The discovery of
    this long-sought-after process is yet another step along the way to a
    better understanding of the Standard Model and the physics beyond.”

    The PEP-II accelerator complex at SLAC, also known as the B Factory,
    allows the BaBar collaboration to study not only B-mesons but also
    several other types of particles including the D-meson. Mesons, of which
    there are about 140 types, are made up of fundamental particles called
    quarks, which can be produced when particles collide at high energy. A
    flurry of particles in a variety of combinations is produced when
    electrons and positrons smash together at high energy in the PEP-II
    collider facility. One of the most elusive results of this flurry is the
    transformation of one particle into its anti-particle in a process
    physicists call “mixing.” Neutral K-mesons, observed more than 50 years
    ago, were the first elementary particles to demonstrate this phenomenon.

    About 20 years ago, scientists observed mixing with the B-meson. Now,
    for the first time, the BaBar experimenters have seen the D-meson
    transform into its anti-particle, and vice versa.

    “This is a very exciting moment for us, having found the missing puzzle
    piece for particle-antiparticle mixing,” said BaBar Spokesman Hassan
    Jawahery, a physics professor at the University of Maryland.

    D-meson mixing is remarkably rare. Of the BaBar experiment’s several
    billion recorded collisions, this study focuses on about a million
    events containing a D-meson decay that are candidates for this effect.

    The experimenters found about 500 events in which a D-meson had changed
    into an anti-D-meson before decaying.

    By observing the rare process of D-meson mixing, BaBar collaborators can
    test the intricacies of the Standard Model. To switch from matter to
    antimatter, the D-meson must interact with “virtual particles,” which
    through quantum fluctuations pop into existence for a brief moment
    before disappearing again. Their momentary existence is enough to spark
    the D-meson’s transformation into an anti-D-meson. Although the BaBar
    detector cannot directly see these virtual particles, researchers can
    identify their effect by measuring the frequency of the D-meson to
    anti-D-meson transformation. Knowing that quantity will help determine
    whether the Standard Model is sufficient or whether it must be expanded
    to incorporate new physics processes.

    “It’s too soon to know if the Standard Model is capable of fully
    accounting for this effect, or if new physics is required to explain the
    observation,” said Jawahery. “But in the coming weeks and months we are
    likely to see an abundance of new theoretical work to interpret what
    we’ve observed.”

    Some 600 scientists and engineers from 77 institutions in Canada,
    France, Germany, Italy, the Netherlands, Norway, Russia, Spain, the
    United Kingdom and the United States work on BaBar. SLAC is funded by
    the US Department of Energy’s Office of Science. UK involvement is
    funded by the Particle Physics and Astronomy Research Council (PPARC),

    Notes for Editors

    Images can be downloaded from http://www.interactions.org/imagebank/
    using the keyword BaBar to search the database.


    Neil Calder, Communications
    Stanford Linear Accelerator Center
    Tel +1 650 926-8707

  • george scaglione March 14, 2007, 14:55

    ljk thank you for this news!! good news? heck,better than that!! i am really excited.this is the best i have heard this year or lol,maybe so far in the 21st century!gotta calm down for a moment…ok i took a deep breath but i have already sent an email to mr calder saying how great this all is and asking a question or two.very respectfully,your friend george

  • James M. Essig March 14, 2007, 22:18

    Hi George & ljk,

    These antimatter oscillations is really interesting stuff. If it does point to physics beyond the standard model, it will be interesting to see where it takes us.


    Your Friend Jim

  • george scaglione March 15, 2007, 9:39

    yes jim really really interesting.as i have stated before and will state again here,if we are smart this could be the beginning of a whole new phase of the space program where antimatter powered ships explore solar system much faster and better than the cev we now project! heck guys i see cev going to the moon but mars? a little less so and beyond? maybe not at all.naturally while “the boys in the back room” are planning our first star ship! thank you very much one and all your friend george

  • ljk July 2, 2008, 14:59

    A cosmic conundrum

    Lincoln Wolfenstein explores the enduring mystery of matter-antimatter