In this work, we study six tree-dominated $B\to a_1(1260)a_1(1260)$ and $b_1(1235)b_1(1235)$ decays in the perturbative QCD (pQCD) approach, where $a_1$ ($b_1$) is a ${}^{3}P_1$ (${}^{1}P_1$) axial-vector meson. Based on the perturbative calculations and phenomenological analysis, we find that (a) the $CP$-averaged branching ratio of $B^0\to a_1^{+}{a}_1^{-}$ decay in the pQCD approach is $54.7\times {10}^{-6}$, which agrees well with the current data and the predictions given in the QCD factorization approach within errors; (b) the numerical results for the decay rates of the other five channels are found to be in the order of ${10}^{-6}$ to ${10}^{-5}$, which could be accessed at $B$ factories and Large Hadron Collider experiments; (c) other physical observables such as polarization fractions and direct $CP$-violating asymmetries are also investigated with the pQCD approach in the present work and the predictions can be confronted with relevant experiments in the near future; (d) the different phenomenologies shown between $B\to a_1{a}_1$ and $B\to b_1{b}_1$ decays are expected to be tested by the ongoing Large Hadron Collider and forthcoming SuperB experiments, which could shed light on the typical QCD dynamics involved in these decay modes, as well as in ${}^{3}P_1$ meson $a_1$ and ${}^{1}P_1$ meson $b_1$.

• Received 8 May 2012

DOI:https://doi.org/10.1103/PhysRevD.86.074016