· Belle II is a particle accelerator experiment located in Tsukuba, Japan, where electrons and positrons (anti-electrons) collide to produce B mesons in order to study the breakdown in the symmetry between matter and antimatter.
· It is an international collaboration involving 26 countries including India. A team led by physicists and engineers from the Tata Institute of Fundamental Research, Mumbai, have built the fourth layer of the vertex detector.
· B-mesons are the particles that contain the B-quark, also known as the beauty or bottom quark.
· This broken symmetry between matter and antimatter is one of the most fundamental questions in particle physics as at the time of the Big Bang some 13.7 billion years ago, the universe was in a fully symmetric state with equal quantities of matter and antimatter.
· The original CP violation, or asymmetry between matter and antimatter, which was discovered in 1964, was found in Kaons — particles containing the strange quark. The effects there were tiny — about one part in a thousand.
· For the particles containing the B quark, the effects of this matter-antimatter symmetry are large; they are of order 100%. The B quarks have much greater asymmetry. They are theoretically much easier to understand they are cleaner.
· Also at CERN, the European Organisation for Nuclear Research, there’s one experiment devoted to B quark physics — the LHCb or the Large Hadron Collider beauty experiment. In this, two proton beams are collided at high energies and the results are observed.
· In the Standard Model – the core theory of particle physics – there are generations of low mass particles (leptons); electrons, the muon and the relatively heavy cousin of the electron, the tau are the leptons.
· These particles are expected to have identical interaction strengths, the so-called couplings, in the Standard Model of weak interactions in physics.
· There is a similar thing in the B quark to S quark decay: The so-called Penguin decays. If any one of this can be established, it would be fairly new physics.
Source : The Hindu
10.03.2019