+ Research: Why Matter and Not Antimatter — Muons?

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An article by Dennis Overbye in the NY Times reports on research at Fermi National Accelerator Laboratory.  

Researchers may have discovered a new clue that could help explain why the universe is composed of matter and not “its evil-twin” antimatter. 

http://www.nytimes.com/2010/05/18/science/space/18cosmos.html

As Overbye explains it, in a mathematically perfect universe, we would be less than dead: we’d never have existed at all.  In the Big Bang, equal amounts of matter and antimatter should have been created and then immediately annihilated each other.

And yet we exist.  Physicists would love to know why.

A team at Fermilab’s Tevatron, known as the DZero collaboration, found that the fireballs produced at their accelerator created pairs of the particles known as muons (sort of fat electrons) slightly more often than they produced pairs of anti-muons.

The miniature universe inside the accelerator went from being neutral to being about 1 percent more matter than antimatter. 

Says Guennadi Borisov, a co-leader of the study from Lancaster University in England, “This result may provide an important input for explaining the matter dominance in our universe.”

The results have been posted on the Internet and submitted to the Physical Review.

Overby writes

It was Andrei Sakharov, the Russian dissident and physicist, who first provided a recipe for how matter could prevail over antimatter in the early universe.  Among his conditions was that there be a slight difference in the properties of particles and antiparticles known technically as CP violation.  In effect, when the charges and spins of particles are reversed, they should behave slightly differently.

  Over the years, a few examples of CP violation have been discovered in rare reactions between subatomic particles that tilt slightly in favor of matter over antimatter, but “not enough to explain our existence,” in the words of Gustaaf Brooijmans of Columbia, who is a member of the DZero team.

The new effect hinges on the behavior of strange particles called neutral B-mesons, which are famous for not being able to make up their minds.  They oscillate back and forth trillions of times a second, between their regular state and their antimatter state.

The mesons are created in the proton-antiproton collisions, and seem to go from their antimatter state to their matter state more rapidly than they go the other way around.  This leads to an eventual preponderance of about 1 percent matter over antimatter, when they decay to muons.

Dr. Brooijmans calls the situation “fairly encouraging,” but says it’s too early to say whether this is enough to explain our existence.  Research into the cause of the still mysterious behavior of the B-mesons is still needed.

The observed preponderance is about 50 times what is predicted by the Standard Model, the suite of theories that has ruled particle physics for a generation.  This means that whatever is causing the B-meson to act this way is “new physics.”  Physicists have long been yearning for such a development.

The most likely explanations, according to Dr. Brooijmans, were some new particle not predicted by the Standard Model, or some kind of new interaction between particles.  He expects that “this is something we should be able to poke at with the Large Hadron Collider.”

Physicists are holding their breath.  Neil Weiner of New York University says “If this holds up, the L.H.C. is going to be producing some fantastic results.

And a theorist at Fermilab, Joe Lykken, says that this announcement is not the equivalent of seeing the face of God, “but it might turn out to be the toe of God.”

Click the link to read Dennis Overbye’s complete article in the Times.

tutoring in Columbus OH:   Adrienne Edwards   614-579-6021  or email  aedwardstutor@columbus.rr.com

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