The CKM matrix describes the mixing between mass eigenstates and eigenstates to the weak interaction of quarks. This matrix has to be unitary and can be parametrized (in the case of three quark families) by four parameters λ, A, η_bar and ρ_bar.
With CKMfitter, you can visualize and analyze the constraints on these parameters by several standard-model (and beyond) measurements.
In this picture, one can see the constraints on eta_bar and rho_bar from individual measurements visualized by coloured regions. The small
red circle shows the allowed region for these parameters when all individual constraints are combined.
Link to the CKMfitter homepage: http://ckmfitter.in2p3.fr/
Contact: Prof. Dr. Heiko Lacker