Together, they form the combined $CP$ transformation. Particles change to antiparticles when acted upon by the Charge conjugation operator Where does it come from? Well, asymmetries have been observed between matter and antimatter, mainly in weak decays, where it has been shown that C-symmetry violation occurs. All matter should have annihilated all antimatter in the early universe, but that clearly did not happen because here we are (sitting on a 'matter chair' drinking 'matter coffee') asking this question. For that reason there should be no matter nor antimatter in our universe. Matter and antimatter annihilates each other and produces photons. In the early universe, right after the Big Bang, equal amount of matter and antimatter was created. It is worth stating that the laws of physics are not completely symmetrical when we make the change from matter $\to$ antimatter. The only difference would be the direction of the force, which will be opposite as seen in the picture below: For example both the electron and the positron travelling along the x-direction will react to an external magnetic field along the y-direction. This makes the behaviour of antimatter to 'reflect' that of its matter partner. Antiparticles in general have opposite quantum numbers which are namely:Īnd others which I'm probably forgetting. The positron has the same mass as the electron, but has opposite electrical charge, i.e +1.īut antimatter does not only distinguish between electric charge. An electron, which is a particle of matter, will have an 'opposite partner' which we named the positron. If the neutral kaon is confirmed to directly violate CP, it may provide an avenue for nature to show a preference for matter over antimatter in the early universe.Antimatter is the 'quantum opposite' of matter. ![]() While normal beta decay violates parity, it is invariant under CP. At the fundamental particle level, nature can tell the difference between left-handed and right-handed systems as indicated by parity violation with neutrinos (neutrinos are left-handed and antineutrinos are right-handed). Current research which may shed some light on the question is that which explores the apparent violation of CP invariance in the decay of the neutral kaon. ![]() We see antimatter today only in pair production, radioactive decay and in the products of the high-energy particle accelerators. Something very early in the history of the universe tipped the balance toward matter to the virtual exclusion of antimatter. Seeing that nature is in so many respects symmetric, a fundamental question is "Why is the universe made out of matter, with very little antimatter? We can create antimatter today in pair production, and in fact the processes of particle production produce equal numbers of particles and antiparticles. This includes more than just electric charge it inverts all internal quantum numbers such as baryon number, lepton number, and strangeness. Going beyond the basics, we can say that an antiparticle is related to the particle by charge conjugation. If an electron encounters a positron, they annihilate with the transformation of their mass energies into two gamma rays. ![]() It has identical mass, but has a positive charge. For example, the positron is the antiparticle of the electron. In the standard model for describing fundamental particles and interactions, every particle has an antiparticle.
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