New success of researchers from University of Nova Gorica – After a publication in Science a new publication in Nature
Physicists from the Laboratory for astroparticle physics of the University of Nova Gorica, the Faculty of Mathematics and Physics of the University of Ljubljana, the Jožef Stefan Institute, Ljubljana and the Faculty of Chemistry and Chemical Engineering of the University of Maribor, who pursue their research of elementary particles within the Belle Collaboration, have together with their international colleagues published a paper on the differences between properties of matter and anti-matter in the most prominent scientific journal Nature (Belle Collaboration, Nature, 452, 332-335 (20 March 2008) | doi:10.1038/nature06827).
Cosmological models assume that the Big Bang produced equal amounts of matter (particles) and anti-matter (anti-particles), however the Universe we are observing today consists entirely of matter. One of the key factors for this kind of evolution of the Universe is CP violation, which describes certain differences between properties of particles and their anti-particles. The international Belle collaboration, experimenting at KEKB electron-positron collider in Tsukuba, Japan is performing precise measurements of differences between subatomic particles, the so-called B mesons and their anti-particles. The paper featured in Nature presents decay rates with which negatively charged B ^-^ decay into K ^-^ p ^0^ particles, and the decay rates of B ^-^ anti-particle decays, B ^+^ → K ^+^ p ^0^. The difference between these decay rates, normalized to the sum of both processes is as large as 7%. The result clearly shows the difference of behaviour of particles and their anti-particles in mirror-like processes, which is due to CP violation.
It is interesting to compare the asymmetry in charged B meson decays (7%) to the same quantity measured in decays on neutral B mesons and their anti-particles, B ^0^ → K ^+^ p ^-^ and anti-B ^0^ → K ^-^ p ^+^. In the neutral B meson decays the asymmetry is negative and has a value of about 10%. Theoretical predictions of the Standard model of elementary particles imply that the two measurements stated above should yield equal asymmetries. This difference perhaps indicates that CP violation might result from sources, which are not included within the framework of the Standard model, the so called New physics, which is essential to adequately describe the full evolution of our Universe from its beginning to the form we see it in today. An interpretation of our measurements by theoretical physicist M. E. Peskin is available in the same issue of Nature (M. E. Peskin, Nature 452, 293-294 (20 March 2008) | doi:10.1038/452293a).
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