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UTA physicists on team finding matter-antimatter asymmetry

University of Texas at Arlington physicists are part of the DZero collaboration research team that has found new evidence that may help explain why the universe is composed of matter. The new findings are outlined in a May 18 article in The New York Times.

The UT Arlington team, headed by physics professor Andrew White, spends time at Fermilab taking shifts for data collection, maintaining the detector and data analysis. The team includes professor Kaushik De, associate professors Andrew Brandt and Jaehoon Yu, researcher Mark Sosebee, and students Arnab Pal and Heather Brown.

Scientists at the Fermilab proton-antiproton collider observe hundreds of millions of high-energy collisions of matter and anti-matter particles every day. When the particles collide, they turn into energy and produce new particles and antiparticles.

"Similar processes occurring at the beginning of the universe should have left us with a universe with equal amounts of matter and antimatter," White said. "But the world around us is made of matter only, and antimatter can only be produced at colliders, in nuclear reactions or cosmic rays. What happened to the antimatter is one of the central questions of 21st century particle physics."

DZero is an international experiment of about 500 physicists from 86 institutions in 19 countries. It is supported by the U.S. Department of Energy, the National Science Foundation and a number of international funding agencies. Fermilab is a national laboratory funded by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.

The dominance of matter that is observable in the universe is possible only if there are differences in the behavior of particles and antiparticles. Although physicists have observed such differences 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 certainly not enough to shed any light on the existence of stars, galaxies or life. Those minute differences are fully consistent with the Standard Model.

In analyzing data from collisions of protons and antiprotons at Fermilab's Tevatron, which until the opening of the Large Hadron collider near Geneva was the largest particle accelerator in the world, the scientists found something inexplicable. In the production of pairs of muon and antimuons scientists found, instead of symmetry, more movement from the antimatter state to the matter state. The difference was an observable one percent.

This evidence found by the DZero Collaboration, if confirmed by further observations and analysis, could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond what we know today. This could mean significant discoveries of new physics studies may be forthcoming from the ATLAS Experiment at the CERN Large Hadron Collider - an experiment in which UT Arlington is a very active participant.