Phenomenological studies on neutral B-meson decays into $$J/\psi f_1$$ and $$\eta _c f_1$$

Abstract The axial-vector mesons $$f_1(1285)$$ f 1 ( 1285 ) and $$f_1(1420)$$ 1420 are particularly viewed as the mixtures of flavor states $$f_n$$ n $$f_s$$ s with mixing angle $$\varphi $$ φ . In order to determine this angle, we study $$B_{d,s}^0\rightarrow J/\psi f_1(1285,1420)$$ B d , 0 → J / ψ \eta _c η c decays in perturbative QCD (PQCD) approach, including effects vertex corrections, nonfactorizable diagrams penguin operators. Not only branching fractions, but also direct CP asymmetries polarization fractions calculated. It is found that these large enough be measured running LHCb Belle-II experiments. Moreover, comparison observed $${\mathcal {B}}(B_{d,s}^0 \rightarrow f_1(1285))$$ , $$B_s^0 (J/\psi _c) f_1(1420)$$ have which could promisingly through $$f_1(1420) K_S^0 K^\pm \pi ^\mp K S ± π ∓ We propose several ratios used further constrain absolute value its sign cannot determined yet decays. indicate pollution $$B_d^0 f_1$$ neglected. acknowledge there theoretical uncertainties arising from distribution amplitudes charmonium states, more precise nonperturbative parameters called. comparisons between our results future experimental data would help us understand nature $$f_1$$ test PQCD approach.