论文标题
关于中性$ b $ -Meson的现象学研究衰减成$ j/ψf_1$和$η_cf_1 $
Phenomenological studies on neutral $B$-meson decays into $J/ψf_1$ and $η_c f_1$
论文作者
论文摘要
轴向矢量介子$ f_1（1285）$和$ f_1（1420）$特别看作是风味状态的混合物$ f_n $和$ f_s $与混合角度$φ$。 In order to determine this angle, we study the $B_{d,s}^0\to J/ψf_1(1285,1420)$ and $B_{d,s}^0\to η_c f_1(1285,1420)$ decays in perturbative QCD (PQCD) approach, including the effects of vertex corrections, nonfactorizable diagrams and penguin操作员。不仅分支分数，而且还计算了直接的$ cp $不对称和极化分数。发现这些衰变的分支部分足够大，可以在运行的LHCB和Belle-II实验中测量。此外，与观察到的$ {\ cal b}（b_ {d，s}^0 \至j/ψf_1（1285））$，$ b_s^0 \ to（j/ψ，η_c）f_1（1420）$可以测量大型分支级别，可以测量$ f_1（1420）实验中的π^\ mp $。我们还提出了几个比率，可以用来进一步限制混合角$φ$的绝对值，但是在这些衰减中尚未确定其符号。这些衰变的直接CP不对称表示$ b_d^0 \ to（j/ψ，η_c）f_1 $衰减中的企鹅污染不能忽略。我们承认，轴向媒介膜和炭状态的分布幅度引起了很大的理论不确定性，调用了更精确的非扰动参数。我们的结果与未来的实验数据之间的比较将有助于我们了解$ f_1 $状态的性质并测试PQCD方法。
The axial-vector mesons $f_1(1285)$ and $f_1(1420)$ are particularly viewed as the mixtures of flavor states $f_n$ and $f_s$ with mixing angle $φ$. In order to determine this angle, we study the $B_{d,s}^0\to J/ψf_1(1285,1420)$ and $B_{d,s}^0\to η_c f_1(1285,1420)$ decays in perturbative QCD (PQCD) approach, including the effects of vertex corrections, nonfactorizable diagrams and penguin operators. Not only the branching fractions, but also the direct $CP$ asymmetries and the polarization fractions are calculated. It is found that the branching fractions of these decays are large enough to be measured in the running LHCb and Belle-II experiments. Moreover, in comparison with the observed ${\cal B}(B_{d,s}^0 \to J/ψf_1(1285))$, $B_s^0 \to (J/ψ, η_c) f_1(1420)$ decays have large branching fractions, which could be measured promisingly through $f_1(1420) \to K_S^0 K^\pm π^\mp$ in experiments. We also propose several ratios that could be used to further constrain the absolute value of the mixing angle $φ$, but its sign cannot be determined yet in these decays. The direct CP asymmetries of these decays indicate the penguin pollution in the $B_d^0 \to (J/ψ, η_c) f_1$ decays cannot be neglected. We acknowledge that there are large theoretical uncertainties arising from the distribution amplitudes of axial-vector mesons and charmonium states, and more precise nonperturbative parameters are called. The comparisons between our results and future experimental data would help us to understand the nature of $f_1$ states and to test the PQCD approach.
