If we exist – if there is the universe as we know it and live – we must thank an accident with physics. Scientists call him Matter anti-material asymmetryand can be told: every particle of “normal” matter corresponds to an opposite load particle, it is done so anti -material; When matter and antimatter come into contact, yes AnnichilanoThat is, they destroy each other by broadcasting energy; Everything suggests that at the time of Bang Matter and anti -material were produced in equal quantities; And that is why something must have intervened at a certain point to make this symmetry unbalanced and to make the prevalence of the first on the second possible. In short, a small surplus that the universe has let exist. Given these buildings, it is easy to understand why the question is so important: to date, the search for the explanation of this asymmetry between matter and antimatter remains one of the greatest puzzles of physics. Well, a group of experiment scientists LHCBled to the large particle accelerator of the Cern Van Geneva, it has just been successful to observe this asymmetry for the first time in the world: it is mentioned in Jargon Violation of equal and indictment ((load-parity violationOr just CP), and it is an effect that was provided with the theoretical models, but so far never immediately observed. The discovery is told about Pages of the magazine Nature.
Matter and antimatter, the mirror of the cosmos
The hypothesis ofexistence of antimatter (not to be confused with the dark matter) stems directly from the comparisons of the quantum mechanicswho regulate the behavior of microscopic particles. It was the body Paul Dirac To predict the existence of the antieletton – a particle right in all respects, apart from the positive electrical charge – in 1928, starting with his relativistic comparison, and the prediction was confirmed experimentally in 1930 thanks to the work of the American physicist Carl David Anderson. Then Dirac also prepared the antiproton, then discovered by a group of physicists of Berkeley Including the Italian also appeared Emilio Segré. A few decades later it was the turn of antiproton one antineutoneFollowed by two hydrogen anti-Isoopes (respectively Anti-Ine Deuter and Antitrice) and finally, in 1997, the first anti-hydrogenatomas. In short, there is no doubt on the fact that antimatter exists: but understand it Why has “lost” compared to matter is another pair of sleeves
What happened to the anti -material?
Maybe someone wondered Matter and antimatter are created in equal quantities But for some reason they did not come into contact, which avoided the phenomenon of destruction that we mentioned earlier. In this case, however, we should have observed somewhere Regions of the universe dominated by antimatteria, whose boundaries with the regions of matter would have produced energy in the form of gamma rays However, because of destruction: all this has never been observed. So there must be another explanation: to justify the domination of the subject, in 1967 the physique Andrej Sacharov In 1967 he proposed three necessary conditions (the so -called Policies of Sacharov for BariogenesisThat is, for creating Barioni – Farmers are a family of subatomic particles), that is the Violation of the barrel number ((“It must be possible to make protons without making an equal number of anti -rotons in a single relationship”); the Violation of symmetries C (conjugation of load) and CP (load and equality) ((“There must be a difference in the behavior between particles and antip items”We will come back soon); there Dynamic outside the thermal balance ((“During the process, the universe should not have been in a state of maximum entropy that generated asymmetry”).
The mystery of the violation of the CP
Let’s concentrate on the SEconda Sacharov state, That is the one who has the most to do with the discovery of today. In the world of particle physics, CP symmetry combines two concepts, the load symmetry, which determines that physical laws remain the same as they exchange particles with their anti -articles, and the symmetry of equality, which refers to how physical laws behave under spatial reflection, as in a mirror. Here, if this symmetry has actually been violated, we would have an explanation for theexcess We were talking about matter in the beginning and therefore for the existence of the universe. The theoretical and experimental history of this hypothesis is long and fascinating. A fundamental theoretical contribution arrived in 1963 thanks to the works of Nicola Cabibbo; Then it was first observed in 1964 in the decline of Mesoni K Neutri, a discovery that the Nobel Prize For Physics A James Cronin one Fitch; Based on the works of Cabibbo, Japanese physicists Makoto Kobayashi one Toshihide Maskawa They suggested that the violation could be included in the standard model, the theory that describes the basic particles and their interactions, provided that there were at least six different types of quarks. This idea was confirmed experimentally decades later, with the observation of the violation of CP symmetry in the decades of a sort of quark from the experiments Babar In the United States and To claim In Japan – and this confirmation meant that Kobayashi and Maskawa received the Nobel for Physics in 2008.
The new LHCB observations
For example, we come to work just published by the scientific cooperation of LHCB (Grote Hadron Collider Beauty – beauty It is a kind of quark). The measures were confirmed from the experiment, for the first time confirmed a violation of CP symmetry between Barioni one antibarionicomposed of Tre Quark and Tre Antiquark. It was not easy to achieve this result: Geneva scientists had to analyze more than eighty thousand farmers and Antibarioni, finally discover “That these farmers fall into specific subatomic particles (a proton, a kaone and two pawns) – He explained William BarterOne of the authors of the work – A little more often (5% more often, to be precise) than what their anti -materials do against. Although it is small, this difference is statistically significant enough to form the first observation of a difference in the behavior of Barioni and Antibarioni “. The new measures are consistent with the theoretical predictions in the standard model, which are still considered too small to justify the enormous asymmetry of the universe. ‘But it is still A big step forward – Still Trade – Because we finally observed directly in the differences between matter and anti -material in the group of particles that dominate the material known in the universe. It is a fundamental step in the direction of Understand why the situation has evolved in this way after the big bang. With the current and future experiments of LHCB we hope to be able to investigate these differences even more and hopefully to find some indications of potential new particles that help us complete this puzzle “.
#Antimatter #matter #observed #CERN #asymmetry #exist