Properties of Axial-vector Mesons and Charmless B Decays: B→VV,VA,AA

I introduce the properties of the light axial-vector mesons. The branching ratios, longitudinal fractions and direct CP asymmetries of the related charmless two-body B decays into final states involving two axial-vector mesons (AA) or one vector and one axial-vector meson (VA) are discussed within the framework of QCD factorization.