Space.com - 18 May 2010
Evidence for an anomalous like-sign dimuon charge asymmetryThe seemingly inescapable fact that matter and antimatter particles destroy each other on contact has long puzzled physicists wondering how life, the universe or anything else can exist at all. But new results from a particle accelerator experiment suggest that matter does seem to win in the end.
The experiment has shown a small — but significant — 1 percent difference between the amount of matter and antimatter produced, which could hint at how our matter-dominated existence came about.
The current theory, known as the Standard Model of particle physics, has predicted some violation of matter-antimatter symmetry, but not enough to explain how our universe arose consisting mostly of matter with barely a trace of antimatter.
But this latest experiment came up with an unbalanced ratio of matter to antimatter that goes beyond the imbalance predicted by the Standard Model. Specifically, physicists discovered a 1 percent difference between pairs of muons and antimuons that arise from the decay of particles known as B mesons.
The results, announced Tuesday, came from analyzing eight years worth of data from the Tevatron collider at the Department of Energy's Fermi National Accelerator Laboratory in Batavia, Ill.
"Many of us felt goose bumps when we saw the result," said Stefan Soldner-Rembold, a particle physicist at the University of Manchester in the United Kingdom. "We knew we were seeing something beyond what we have seen before and beyond what current theories can explain."
The Tevatron collider and its bigger cousin, the Large Hadron Collider at CERN in Switzerland, can smash matter and antimatter particles together to create energy, as well as new particles and antiparticles. Otherwise, antiparticles only arise due to extreme events such as nuclear reactions or cosmic rays from dying stars.
Measurements made by the DZero collaboration, a 500-member international group, are still limited by the number of collisions recorded so far. That means physicists will continue to collect data and refine their analysis of the matter-antimatter struggle for dominance.
Researchers came up with their latest finding by performing a so-called blind data analysis, so that they would not bias their analyses based on what they observed. They have submitted their results to the journal Physical Review D.
Fermilab scientists find evidence for significant matter-antimatter asymmetry
Fermilab Press Room - 18 May 2010
Fermi's Tevatron finds another bias against antimatter
ars technica > Nobel Intent > 18 May 2010
