• Number 312  |
• May 24, 2010

Evidence for significant matter-antimatter asymmetry

Scientists of the DZero collaboration at DOE's Fermi National Accelerator Laboratory have found evidence for significant violation of matter-antimatter symmetry in the behavior of particles containing bottom quarks beyond what is expected in the current theory, the Standard Model of particle physics. The new result, submitted for publication in Physical Review D, indicates a one percent difference between the production of pairs of muons and pairs of antimuons in the decay of B mesons produced in high-energy collisions at Fermilab's Tevatron particle collider.

The dominance of matter that we observe in the universe is possible only if there are differences in the behavior of particles and antiparticles.

Although physicists have observed such differences (called "CP violation") in particle behavior for decades, these known differences are much too small to explain the observed dominance of matter over antimatter in the universe and are fully consistent with the Standard Model.  If confirmed by further observations and analysis, the effect seen by DZero physicists could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond what we know today.

Using unique features of their precision detector and newly developed analysis methods, the DZero scientists have shown that the probability that this measurement is consistent with any known effect is below 0.1 percent (3.2 standard deviations).

[Rhianna Wisniewski, 630.840.6733,
rhianna@fnal.gov]