CPsymmetry

CPsymmetry refers to the invariance of physical laws under the combined operation of charge conjugation (C) and parity inversion (P). Charge conjugation, denoted by C, is a symmetry operation that swaps particles with their corresponding antiparticles. For example, it would transform an electron into a positron. Parity inversion, denoted by P, is a spatial inversion operation that flips the signs of all spatial coordinates, effectively creating a mirror image of a system.

In classical physics, many fundamental laws exhibit both charge conjugation symmetry and parity symmetry individually. However, it was discovered in the mid-20th century that some weak interactions violate both C and P symmetries independently. CP symmetry, the combined symmetry, states that if a process is followed by its charge-conjugated and parity-inverted counterpart, the laws of physics should remain the same.

The violation of CP symmetry implies that the universe might distinguish between matter and antimatter. If CP symmetry were perfectly conserved, then the amount of matter and antimatter created in the early universe would have been equal. However, the observed abundance of matter over antimatter suggests that CP symmetry must be violated. This violation is a crucial ingredient in theories attempting to explain the matter-antimatter asymmetry in the universe. Experimental evidence for CP violation was first observed in the decay of neutral kaons and later in the decay of neutral B mesons.