Members of the international collaboration DZero, working at the Tevatron collider at the National Accelerator Laboratory. Fermi, reported on the registration of a new case of violation of CP-invariance, which does not fit into the framework of the Standard Model of particle physics.

Physics cannot yet answer the question of why matter predominates in the modern Universe. In 1967, Andrei Dmitrievich Sakharov showed that the required imbalance arises shortly after the Big Bang when certain conditions are met, one of which is the violation of CP invariance.

Specular reflection and replacement of particles with their antiparticles are traditionally denoted by the letters P and C; violation of CP symmetry, thus, indicates the non-invariance of the laws of physics with respect to the two indicated operations. Examples of this phenomenon are well known. In 1964, in experiments with neutral kaons (K-mesons), it was registered by employees of the Brookhaven National Laboratory. In 2001, cases of violation of CP invariance were noted in the analysis of the decay of B mesons.

But the observed CP violation, which is consistent with the Standard Model, does not allow explaining the predominance of matter, since the effect they produce is too small. This forces physicists to look for new experimental ways to register the violation.

In order to reduce the error of the result, the scientists changed the direction of the magnetic field in the DZero detector, which determines the trajectory of the movement of muons and anti-muons. Above and below trajectories are shown for opposite directions.

The authors of the work under consideration have recorded the decay of neutral B-mesons formed in collisions of protons and antiprotons on the Tevatron. The data analyzed in the study was collected from April 2002 to June 2009, which corresponds to an integrated luminosity of 6.1 fb^-one (in other words, a hypothetical process with a cross section of 1 fb would have occurred approximately six times during this time).

As it turned out, the frequency of occurrence of muon pairs µ^– as a result of B-meson decay, it exceeded the frequency of anti-muon pair production µ by one percent⁺, which is evidence of the violation of CP invariance. To be precise, the measured skewness parameter was -0.00957, while the Standard Model predicts a value of about -0.00023. The first value exceeds the second by about 41 times.

“This result is different from anything we have seen before, and it will be very difficult to explain it within the framework of modern theories,” summarizes Stefan Soldner-Rembold, a spokesman for DZero.

Accelerator complex of the National Laboratory named after V.I. Fermi (photo by Fermilab).

Source: computerra.ru