Effects of family non-universal Z′model in angular observables of B→(ρ,a_(1))µ^(+)µ^(−)decays

We present the angular distribution of the four-fold B→ρ(→ππ)µ^(+)µ^(−) and B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decays in the Standard Model and family non-universal Z'model.At the quark level,these decays are govered by the b→dµ^(+)µ^(−) transition.Along with different angular observables,we provide predictions of differential branching ra.tios,forward-backward asymmetry,and longitudinal polarization fractions of ρ and a_(1) mesons.Our analysis showsthat the signatures of the fimily non-universal Z’model are more distinct in the observables associated with the B→ρ(→ππ)µ^(+)µ^(−) decay than in those associated with the B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decay.Future measurements ofthe predicted angular observables,both at current and fiuture high energy colliders,will provide useful complement.ary data required to clarify the structure of the family non-universal Z' model in |△b|=△d|=1 processes.