From: LARRY KLAES (ljk4_at_msn.com)
Date: Wed Mar 14 2007 - 06:59:00 PDT
>From: "AAS Press Officer Dr. Steve Maran" <Steve.Maran_at_aas.org>
>To: "AAS Press Officer Dr. Steve Maran" <steve.maran_at_aas.org>
>Subject: PPARC: Matter Found Becoming Anti-Matter in New Way
>Date: Tue, 13 Mar 2007 13:12:21 -0400
>
THE FOLLOWING RELEASE WAS RECEIVED FROM THE PARTICLE PHYSICS AND ASTRONOMY
RESEARCH COUNCIL, IN THE U.K., AND IS FORWARDED FOR YOUR INFORMATION.
(FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE AMERICAN ASTRONOMICAL
SOCIETY.) Steve Maran, American Astronomical Society maran_at_aas.org
1-202-328-2010 x116
**Contact data appear below**
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.
CONTACT:
Neil Calder, Communications
Stanford Linear Accelerator Center
Tel +1 650 926-8707
neil.calder_at_slac.stanford.edu
Julia Maddock
PPARC Press Office
Tel +44 1793 442094
Julia.maddock_at_pparc.ac.uk
COMMENT:
UK BaBar spokesman
Fergus Wilson (currently at SLAC)
CCLRC Rutherford Appleton Laboratory
F.F.Wilson_at_rl.ac.uk
Tel: +01-650-926-3761
UK Scientist:
Dr Christos Touramanis
University of Liverpool
Tel +44 151 794-6970
mobile: (44)797 324-7767
christos_at_slac.stanford.edu
US Comment:
Hassan Jawahery, BaBar Spokesman
Tel +1 650 926-4781
jawahery_at_slac.stanford.edu
RELEVANT WEBSITES:
STANFORD LINEAR ACCELERATOR CENTER
http://www.slac.stanford.edu
BABAR COLLABORATION
http://www-public.slac.stanford.edu/babar/
The Particle Physics and Astronomy Research Council (PPARC) is the UK's
strategic science investment agency. It funds research, education and
public understanding in four areas of science - particle physics,
astronomy, cosmology and space science.
PPARC is government funded and provides research grants and studentships
to scientists in British universities, gives researchers access to
world-class facilities and funds the UK membership of international
bodies such as the European Laboratory for Particle Physics (CERN), and
the European Space Agency. It also contributes money for the UK
telescopes overseas on La Palma, Hawaii, Australia and in Chile, the UK
Astronomy Technology Centre at the Royal Observatory, Edinburgh and the
MERLIN/VLBI National Facility, which includes the Lovell Telescope at
Jodrell Bank observatory.
PPARC's Public Understanding of Science and Technology Awards Scheme
funds both small local projects and national initiatives aimed at
improving public understanding of its areas of science.
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1-202-328-2010 X116
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