The Jarlskog invariant or rephasing-invariant CP violation parameter, is an invariant quantity in particle physics, which is in the order of ±2.8 x 10. This parameter is related to the unitarity conditions of the Cabibbo–Kobayashi–Maskawa matrix, which can be expressed as triangles whose sides are products of different elements of the matrix. As such, the Jarlskog invariant can be written as J = ±Im(V us V cb V ub V cs), which amounts to twice the area of the unitarity triangle. Because the area vanishes for the specific parameters in the Standard Model for which there would be no CP violation, this invariant is thus very useful to quantify the non-conservation of the CP-symmetry in elementary particle physics. It is one of Jarlskog's foremost contributions to physics, the other being the many years that she was an active member of CERN.