On a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi><mml:mi>P</mml:mi></mml:math>anisotropy measurement in the Dalitz plot

We describe a novel use of the Dalitz plot to probe $CP$ symmetry in three-body modes of $B$ and $D$ mesons. It is based on an observable inspired by astronomers' practice, namely the significance in the difference between corresponding Dalitz plot bins. It provides a model-independent mapping of local $CP$ asymmetries. We illustrate the method for probing $CP$ symmetry in the two complementary cases of $B$ and $D$ decays: in the former sizable or even large effects can be expected, yet have to be differentiated against leading standard model contributions, while in the latter one cannot count on sizable effects, yet has to deal with much less standard model background.