Physics – asymmetrically decaying particles

In experiments on the particle accelerator Hadron Collider of the core research center Cern, scientists were able to show for the first time that the decay of severe subatomar particles and their anti -particle has statistically significant differences. This proof could help to better understand the standard model of the elementary particle physics and thus ultimately the development of the universe in its earliest times.

At first not surprisingly, the universe consists of stable matter: the positively charged protons, the neutral neutrons (both heavy particles that are built up of three quarks) and the light, negatively charged electrons. In 1928 the British physicist Paul Dirac predicted the existence of an anti -particle to the electron: The “Positron” would therefore have the same mass as the electron, but a positive load and a reverse magnetic moment. Most physical laws are not impressed by this – they run for particles and anti -particles immediately, they show a “symmetry”.

If electron and positron now meet, the particles are destroyed (“annihilated”) and radiation of a precisely determined energy becomes free. According to today, each particle has an anti -particle.

According to today, each particle has an anti -particle.

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Common cosmological models assume that the same amount of matter and antimacy occurred during the big bang – but why the universe today consists exclusively of matter is one of the great still unexplained questions of physics. One possibility would be that at the beginning there was a tiny surplus of matter that survived the great annihilation; However, it is more likely that matter and antimatter are not as symmetrical as assumed. Particles and antipartels therefore have slightly different, ie “asymmetrical” properties, and the fact that is observed today would be the result of a dynamic development of the universe.

Specifically, it is about the violation of the CP invariance, i.e. the expectation that physical laws and relationships will remain the same when particles are replaced by their anti-particles (“c” by English batch, load) and at the same time all room coordinates are mirrored (“p” by English parity, parity). A particle should therefore also decay as much as its anti -particle.

Already from experiments in the 1960s it was known that a group of elementary particles, which showed medium and unstable mesons, a violation of this CP invariance. In 1964, physicists at the University of Princeton carried out an experiment to disintegrate “K-Meson”. It was shown that the weak interaction-one of the basic forces of physics-violated CP symmetry, which indicated that matter and antimatter could actually behave differently. In 1980 there was the Nobel Prize for Physics, and the Soviet physicist Andrej Sacharow suspected for the first time that the CP injury, increasingly on the high mass scales in the early universe, could have caused a matter-antimacy asymmetry shortly after the big bang.

In the “Large Hadron Collider Beauty” experiment (LHCB), new heavy particles, the so-called Delta-Baryons and their antiparticles, were created in the collision of two protons under the highest energies. While protons and neutrons from “Up” and “Down Quarks” are built up, the Delta-Baryon is even more exotic quark, the heavy “bottom quark”. For the first time, scientists have succeeded in creating a sufficient number of these (anti) baryoses and recording their decays with the high-precision detector of the LHCB experiment: more than 80,000 decays have been detected in order to be able to demonstrate the matter antimacy asymmetry. However, the extent of the observed CP injury of the Delta-Baryons and their anti-particles is not sufficient to explain the matter-antimacy-making weight in the Big Bang. Nevertheless, the details of the experiment provide important information for further theoretical and experimental studies for possible physics beyond the standard model.