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Amir Rahimi

BaBar Reports Evidence for New Form of Matter-Antimatter Oscillations

Last week, the BaBar experiment at the Stanford Linear Accelerator Center (SLAC) announced a major physics result: for the first time ever, they had seen matter particles, so called D-mesons, transition into their antimatter counterparts. The existence of this process, also referred to as "D mixing," has been subject of debate by physicists for over thirty years and many current and former high-energy physics experiments have searched for it. Ohio State physicist Dr. Amir Rahimi is a member of the small team that made the first observation of these rare and illusive events. "After many years of work", Rahimi says, "It is exciting to finally have unmistakable evidence for D mixing."

So what is the value of this new result? SLAC director Jonathan Dorfan calls the Standard Model of particle physics, the theory that so successfully describes the ordinary matter particles and the fundamental interactions between them, one of the greatest scientific triumphs of the twentieth century. Nevertheless we know the Standard Model cannot be fully correct. Ever more precise measurements and/or elucidation of yet unobserved phenomena - like BaBar's first observation of D mixing - allow us to probe the Model yet more incisively. This new result leaves open an intriguing question about the origin of the effect. Is it due to known physics of the Standard Model, or is it due to new processes previously unseen? Over the coming months we expect to see a flurry of new theoretical work from researchers worldwide to interpret these observations while Dr. Rahimi and his colleagues continue to analyze the enormous BaBar data sample seeking further evidence for D mixing... so stay tuned.

A paper describing this result has been submitted to Physics Review Letters.

More information on the Ohio State BaBar group can be found here.

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