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arXiv 1008.5201hep-ph
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用微扰QCD方法研究轻标量介子和无粲强子$B_c \to SP, SV$衰变

Light scalar mesons and charmless hadronic $B_c \to SP, SV$ decays in the perturbative QCD approach

Xin Liu, Zhen-Jun Xiao

备注：
24 pages, 1 figure, accepted for publication in Physical Review D
发表信息：
Phys.Rev.D82:054029,2010
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摘要：

本文在标量双夸克结构假设的基础上，研究了无粲强子$B_c \to SP, SV$衰变（这里$S$，$P$和$V$分别表示轻标量、赝标量和矢量介子），通过数值计算和唯象分析，我们发现：（a）所考虑的$B_c$衰变的{ \it CP}平均分支比（BR）的pQCD预测在$10^{-5}$到$10^{-8}$的范围内变化，这将在正在进行的LHCb和即将到来的Super-B实验中进行测试，而这些模式的{ \it CP}违反不对称性在标准模型中自然不存在，因为只涉及一个类型树算子; %%（b）类似于$B \to K^* η^{(\prime)}$衰变，pQCD方法中的$Br(B_c \to κ^+ η) \sim 5 \times Br(B_c \to κ^+ η^\prime)$，这可以通过$η_q$和$η_s$对$B_c \to κ^+ η$和$B_c \to κ^+ η^\prime$衰变的贡献之间的相长干涉和相消干涉来理解，然而，在两种情况下，$Br(B_c \to K_0^*(1430) η)$近似等于$Br(B_c \to K_0^*(1430) η')$，因为来自$η_s$项的可因子分解贡献在所考虑的两个信道中起主导作用;（c）如果$a_0(980)$和$κ$是$q\bar q$的束缚态，那么pQCD预测的$B_c \to a_0(980) (π, ρ)$和$B_c \to κK^{(*)}$衰变的BR将在$10^{-6} \sim 10^{-5}$的范围内，这在LHCb实验的范围内，并且可以在不久的将来测量;对于$a_0(1450)$和$K_0^*(1430)$通道，发现pQCD方法中$B_c \to a_0(1450) (π, ρ)$和$B_c \to K_0^*(1430) K^{(*)}$模式的BR分别为$(5 \sim 47) \times 10^{-6}$和$(0.7 \sim 36) \times 10^{-6}$。

英文摘要：

In this work, based on the assumption of two-quark structure of the scalars, the charmless hadronic $B_c \to SP, SV$ decays(here, $S$, $P$, and $V$ denote the light scalar, pseudoscalar, and vector mesons, respectively) are investigated by employing the perturbative QCD(pQCD) factorization approach.From our numerical evaluations and phenomenological analysis, we find that (a) the pQCD predictions for the {\it CP}-averaged branching ratios(BRs) of the considered $B_c$ decays vary in the range of $10^{-5}$ to $10^{-8}$, which will be tested in the ongoing LHCb and forthcoming Super-B experiments, while the {\it CP}-violating asymmetries for these modes are absent naturally in the standard model because only one type tree operator is involved; %% (b) analogous to $B \to K^* η^{(\prime)}$ decays, $Br(B_c \to κ^+ η) \sim 5 \times Br(B_c \to κ^+ η^\prime)$ in the pQCD approach, which can be understood by the constructive and destructive interference between the $η_q$ and $η_s$ contributions to the $B_c \to κ^+ η$ and $B_c \to κ^+ η^\prime$ decays, however, $Br(B_c \to K_0^*(1430) η)$ is approximately equal to $Br(B_c \to K_0^*(1430) η')$ in both scenarios because the factorizable contributions from $η_s$ term play the dominant role in the considered two channels; %% (c) if $a_0(980)$ and $κ$ are the $q\bar q$ bound states, the pQCD predicted BRs for $B_c \to a_0(980) (π, ρ)$ and $B_c \to κK^{(*)}$ decays will be in the range of $10^{-6} \sim 10^{-5}$, which are within the reach of the LHCb experiments and could be measured in the near future; and %% (d) for the $a_0(1450)$ and $K_0^*(1430)$ channels, the BRs for $B_c \to a_0(1450) (π, ρ)$ and $B_c \to K_0^*(1430) K^{(*)}$ modes in the pQCD approach are found to be $(5 \sim 47) \times 10^{-6}$ and $(0.7 \sim 36) \times 10^{-6}$, respectively.

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