CP violation (SPP)

Babar : α angle measured using the B0 -> -> ρ+ ρ- ,mode and shown in the CP violation parameter plane , ρ, η.
The hotter colours (maximum : red) correspond to the highest probabilities of the parameter values. The black triangle corresponds to the previous measurements of the
parameters. The fact that its apex coincides with a red area illustrates the coherence of the latest measurement with the older ones.

In 1964, an asymmetry between matter and anti-matter was discovered in a special context which allows for very accurate measurements. This fi nding is still providing questions and constraints on models. Indeed, it is related to the entire universe (without it, matter and anti-matter would have annihilated at the Big Bang!), and to the microscopic structure (in the Standard Model, it stems from the presence of 3 families of similar particles). Two groups are involved on this program: in the NA48 experiment at Cern, and in the Babar experiment at SLAC, USA.

#570 - Last update : 02/10 2005

Particle Physics Division

Institute of Research into the Fundamental Laws of the Universe