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Charmless hadronic $B \to (f_1(1285),f_1(1420)) P$ decays in the perturbative QCD approach

We study 20 charmless hadronic $B \to f_1 P$ decays in the perturbative QCD(pQCD) formalism with $f_1$ representing axial-vector mesons $f_1(1285)$ and $f_1(1420)$ that result from a mixing of quark-flavor $f_{1q}$ and $f_{1s}$ states with the angle $ϕ_{f_1}$. The estimations of branching ratios and CP asymmetries of the considered $B \to f_1 P$ decays are presented in the pQCD approach with $ϕ_{f_1} \sim 24^\circ$ from recently measured $B_{d/s} \to J/ψf_1(1285)$ decays. It is found that (a) the tree(penguin) dominant $B^+ \to f_1 π^+(K^+)$ decays with large branching ratios[${\cal O}(10^{-6})$] and large direct CP violations(around 14% $\sim$ 28% in magnitude) simultaneously are believed to be clearly measurable at the LHCb and Belle II experiments; (b) the $B_d \to f_1 K_S^0$ and $B_s \to f_1 (η, η^{\prime})$ decays with nearly pure penguin contributions and safely negligible tree pollution also have large decay rates in the order of $10^{-6} \sim 10^{-5}$, which can be confronted with the experimental measurements in the near future; (c) as the alternative channels, the $B^+ \to f_1 (π^+, K^+)$ and $B_d \to f_1 K_S^0$ decays have the supplementary power in providing more effective constraints on the Cabibbo-Kobayashi-Maskawa weak phases $α$, $γ$, and $β$ correspondingly, which are explicitly analyzed through the large decay rates and the direct and mixing-induced CP asymmetries in the pQCD approach and are expected to be stringently examined by the measurements with high precision. The complete abstraction can be found in the paper.