laengpariteetsümmeetria

Laengpariteetsümmeetria, often abbreviated as CP-sümmeetria, refers to a fundamental concept in particle physics that combines charge conjugation (C) and parity transformation (P). Charge conjugation is an operation that flips the sign of all internal quantum numbers of a particle, effectively transforming a particle into its antiparticle. Parity transformation, on the other hand, is a spatial inversion, which reflects the spatial coordinates through the origin. CP-sümmeetria posits that the laws of physics remain unchanged if a particle is simultaneously replaced by its antiparticle and its spatial coordinates are inverted.

Historically, it was believed that both charge conjugation (C) and parity (P) symmetries were independently conserved in all physical interactions. However, experiments in the 1950s and 1960s demonstrated that parity is violated in weak interactions. Later, it was found that charge conjugation is also violated in certain weak decays. CP-sümmeetria was then proposed as a combined symmetry that might still hold.

The observation of CP-violation in the decay of neutral kaons in 1964 was a significant discovery. This violation implies that the universe is not perfectly symmetric with respect to the combined CP transformation. Further experiments have confirmed CP-violation in other systems, such as B mesons. The existence of CP-violation is crucial for explaining the observed asymmetry between matter and antimatter in the universe, a phenomenon known as the matter-antimatter asymmetry problem. If CP were perfectly conserved, the Big Bang would have produced equal amounts of matter and antimatter, which would have annihilated each other, leaving behind only radiation. The observed abundance of matter suggests that some process must have led to a slight excess of matter over antimatter during the early universe, and CP-violation is a key candidate mechanism for this.