The two-body hadronic decays of B mesons into pseudoscalar and axial vector mesons are studied within the framework of QCD factorization. The light-cone distribution amplitudes (LCDAs) for $^3P_1$ and $^1P_1$ axial-vector mesons have been evaluated using the QCD sum rule method. Owing to the G-parity, the chiral-even two-parton light-cone distribution amplitudes of the $^3P_1$ ($^1P_1$) mesons are symmetric (antisymmetric) under the exchange of quark and anti-quark momentum fractions in the SU(3) limit. For chiral-odd LCDAs, it is other way around. The main results are the following: (i) The predicted rates for $a_1^\pm(1260)π^\mp$, $b_1^\pm(1235)π^\mp$, $b_1^0(1235)π^-$, $a_1^+K^-$ and $b_1^+K^-$ modes are in good agreement with the data. However, the naively expected ratios $Br(B^-\to a_1^0π^-)/Br(\ov B^0\to a_1^+π^-)\leq 1$, $Br(B^-\to a_1^-π^0)/Br(\ov B^0\to a_1^-π^+)\sim {1\over 2}$ and $Br(B^-\to b_1^0K^-)/Br(\ov B^0\to b_1^+K^-)\sim {1\over 2}$ are not borne out by experiment. This should be clarified by the improved measurements of these decays. (ii) Since the $\bar B\to b_1K$ decays receive sizable annihilation contributions, their rates are sensitive to the interference between penguin and annihilation terms. The measurement of $Br(\bar B^0\to b_1^+K^-)$ implies a destructive interference which in turn indicates that the form factors for $B\to b_1$ and $B\to a_1$ transitions are of opposite signs. (iii) Sizable power corrections such as weak annihilation are needed to account for the observed rates of the penguin-dominated modes $K_1^-(1270)π^+$ and $K_1^-(1400)π^+$.
Flavor SU(3) analysis of heavy meson ($B$ and $D$) hadronic charmless decays can be formulated in two different ways. One is to construct the SU(3) irreducible representation amplitude (IRA) by decomposing effective Hamiltonian according to the SU(3) transformation properties. The other is to use the topological diagrams (TDA). These two methods should give equivalent physical results in the SU(3) limit. Using $B \to PP$ decays as an example, we point out that previous analyses in the literature using these two methods do not match consistently in several ways, in particular a few SU(3) indepe…
Recently Belle collaboration reported new measurements for the branching fractions with the first observing two processes of $\mathcal{B}(Ξ_c^0\toΛK^0_S)$, $\mathcal{B}(Ξ_c^0\toΣ^0 K^0_S)$ and updating data for $\mathcal{B}(Ξ_c^0\toΣ^+ K^-)$. Combined with other known data on charmless two body decays of anti-triplet charmed baryons, a lot of information can be derived with the assistance of $SU(3)$ flavour symmetry. Using $SU(3)$ relations between different decay modes, we can give some predictions based on the new measurements which can be tested with the high luminosity experiments in the f…
Within the framework of perturbative QCD factorization, we investigate the nonfactorizable contributions to these factorization-forbidden Quasi-two-body decays $B_{(s)}\rightarrow hχ_{c0}\rightarrow hπ^+π^-(K^+K^-)$ with $ h=π, K$. We compare our predicted branching ratios for the $B_{(s)}\rightarrow Kχ_{c0}\rightarrow Kπ^+π^-(K^+K^-)$ decay with available experiment data as well as predictions by other theoretical studies. The branching ratios of these decays are consistent with data and other theoretical predictions. In the Cabibbo-suppressed decays $B_{(s)}\rightarrow hχ_{c0}\rightarrow hπ^…
The CP violating phase $γ$ from global fit of rare charmless hadronic B decays
利用已有的实验数据研究了Kobayashi-Maskawa模型中CP破坏相$γ$的约束条件。我们首先遵循传统的方法，通过使用来自$|ε_K|$、$Δm_{B_{d,s}}$和$|V_{ub}/V_{cb}|$的数据执行$χ^2$分析来更新对$γ$的约束。我们还将$\sin2β$的最新信息纳入分析中。我们得到了$γ$的最佳拟合为$66^\circ$和95%C. L.允许范围为$42^\circ \sim 87^\circ$。然后，我们开发了一种方法来进行基于SU（3）对称性的$χ^2$分析使用的数据从$B\to ππ$和$B\to K π$。我们还从模型估计的角度讨论了SU（3）破缺效应。我们发现，目前的数据$B\to ππ, K π$也可以给一些约束$γ$虽然弱于早期的方法所限制的目前的实验误差。未来改进的数据将提供更严格的约束。最后，我们使用$|ε_K|$，$Δm_{B_{d,s}}$，$|V_{ub}/V_{cb}|$，$\sin2β$和罕见的无粲强子B衰变的数据进行了组合拟合。组合分析给出$γ=67^\circ$为最佳拟合值，$43^\circ \sim 87^\circ$为95% C. L。允许的范围。对其他基于SU（3）对称性确定$γ$的方法也作了评述。
Several baryons containing a heavy b-quark, the b-baryons, have been discovered. The charmless two-body decays of b-baryons can provide a new platform for CP violating studies in a similar way as charmless two-body decays of B-meson. In b-baryon decays there are new CP violating observable related to baryon polarization. We show that in the flavor $SU(3)$ limit there exist relations involve different combinations of the decay amplitudes compared with those in CP violating rate asymmetry. These new relations therefore provide interesting tests for the mechanism of CP in the standard model (SM) …
NNLO Vertex Corrections in charmless hadronic B decays: Imaginary part
我们在QCD因式分解框架下计算了强子二体衰变的2圈顶点修正的虚部B -> pi pi。这完成了拓扑树振幅虚部的NNLO计算，并代表了QCD因式分解中直接CP不对称性的NNLO预测的重要一步。关于技术方面，我们发现，软共线红外发散取消硬散射内核，这表明因式分解在2圈顺序。所有的结果得到解析，包括依赖于粲夸克质量。数值的NNLO校正的影响被认为是显着的，特别是它们导致增强的强相位的颜色抑制树振幅。
我总结的结果和性能的无粲强子B衰变的动力学理论的基础上，在重夸克极限的QCD因式分解。在理论方面，现在有许多NNLO（α_s^2）振幅可用，它们都表现出良好的微扰展开。在B 0-> pi 0 pi 0中观察到的大分支分数仍然是一个挑战，这意味着B介子波函数的大逆矩或相当大的功率校正（或意想不到的新物理）。B-工厂/Belle 2对B -> gamma I nu的分析可能对此有所启示。另一方面，新的Belle和LHCb测量A_CP（pi^+ pi^-）使实验结果更接近QCDF预测，类似于在B -> pi K衰变中发现的结果，而S_pipi给出了竞争性的γ确定。我提醒读者，对于矢量-矢量终态，自B工厂时代以来，已经存在一套完整的螺旋度振幅的理论处理方法，并取得了一些成功，并且同样适用于LHCb测量，例如B_s -> phi phi。
Utilizing all the experimental measured charmless $B \to PP$, $PV$ decay modes, where $P(V)$ denotes a light pseudoscalar (vector) meson, we extract the CKM angle $γ$ by global fit. All the unknown hadronic parameters are fitted with $γ$ together from experimental data, so as to make the approach least model dependent. The different contributions for various decay modes are classified by topological weak Feynman diagram amplitudes, which are to be determined by the global fit. To improve the precision of this approach, we consider flavor SU(3) breaking effects of topological diagram amplitudes…
We propose a theoretical framework to understand the observable charge-parity (CP) violation in charmless three-body $B^\pm$ decays. The decay amplitudes put together the $ππ\to KK $ re-scattering and the U-spin symmetry, treated within a CPT invariant framework. This approach applied to a two-channel model provides the magnitudes and signs of the ratios of the global CP asymmetries for $B^\pm \to K^\pm π^+ π^- \,$, $B^\pm \to K^\pm K^+ K^- \,$, $B^\pm \to π^\pm K^+ K^- \,$ and $B^\pm \to π^\pm π^+π^- \,$ decays, compatible with those obtained from the available experimental data. In addition,…
The LHCb experiment has measured CP violation (CPV) across the Dalitz plot of charmless decays of B+ mesons to 3 charged tracks, namely in Kππ, KKK, πππ and πKK final states, with strikingly large CPV that vary strongly with Dalitz variables. Identifying these processes with b -> sqq(bar), sss(bar) and b -> dqq(bar), dss(bar), where q = u, d, then the "sum rule" that requires two-loop absorptive parts by unitarity works well for inclusive b -> s CPV, but less well for inclusive b -> d case. We elucidate the situation, and argue that the 30 year old unitarity/CPT argument is valid to this day, …
Extracting Weak Phases Cleanly from Charmless 3-Body B Decays
在过去，人们认为，人们不能获得清洁的弱相位信息的测量CP破坏的不对称性在3体B衰变。最近的研究表明，这是不正确的-通过表示的衰减幅度的图表和使用Dalitz图，可以解决所有的困难和干净地提取弱相位。在这次演讲中，我描述了如何做到这一点，并提出了使用衰变B -> K pi pi和B -> K Kbar K测量伽马的初步结果。
