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New LHC study puts `the end` to antimatter `flip`

Last Updated: Friday, March 1, 2013 - 16:32

London: For the first time, researchers at the Large Hadron Collider have observed particles called D-mesons flipping from matter into antimatter and back.

Such "oscillations" are well known among three other particle types, but this is the first time D-mesons have been seen doing it in a single study, the BBC reported.

Mesons are part of a large family of particles made up of the fundamental particles known as quarks.

The protons and neutrons at the centres of the atoms of matter are each made up of three such quarks.

Mesons, on the other hand, are made of just two - specifically one quark and one antimatter quark.

Theory holds that four members of the meson family can undergo the matter-antimatter oscillation - the matter and antimatter quarks both flip to their opposites.

Three particle types - K-mesons and two types of B-mesons had been caught in the act before.

LHCb has already been intimately involved in refining those prior measurements; in March 2012, the team confirmed earlier oscillation observations of a meson called Bs, and published the result in Physics Letters B.

Now, the team has published results that set a new record of precision on the oscillations of the B0 meson, in the same journal.

This is the last of the four mesons that had never been seen flipping from matter to antimatter and back in a single measurement.

Other experiments had seen some evidence of the D-meson`s flipping, but this is the first that crosses the "five sigma" level of statistical significance that particle physicists use to denote an official discovery.

"This is a nice moment, it`s a sort of completeness," said Chris Parkes of the University of Manchester, spokesman for UK participation in the LHCb experiment.

"There are four systems in nature that oscillate, and this is the last one where a single-channel measurement has crossed the five-sigma threshold - we know now about mixing in all four of these systems," he told BBC News.

Mesons measured by LHCb have hinted at an answer to why the Universe is made overwhelmingly of matter rather than anti matter, which is the next target for the team, said Prof Parkes.

The team behind the collider`s LHCb detector has put their results on the Arxiv repository and the manuscript will be published in Physical Review Letters.


First Published: Friday, March 1, 2013 - 16:32
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