Antimatter’s Oscillations Probed

by Paul Gilster on September 27, 2006

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.

Adam September 28, 2006 at 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 at 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 at 3:28


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 at 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
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 at 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 at 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 at 9:39

yes jim really really 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 at 14:59

A cosmic conundrum

Lincoln Wolfenstein explores the enduring mystery of matter-antimatter

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