References, two plots and additional comments on the LHC bounds added, conclusions unchanged: 11 pages, 3 Figures, invited talk presented at QCD@Work 2014, Giovinazzo (Bari,Italy) June 16-19, 2014. To be published by EPJ Web of Conferences
I summarize the status of the $ΔI=1/2$ rule in $K\toππ$ decays within an {\it analytic} approach based on the dual representation of QCD as a theory of weakly interacting mesons for large $N$, where $N$ is the number of colours. This approximate approach, developed in the 1980s by William Bardeen, Jean-Marc Gérard and myself, allowed us already 28 years ago to identify the dominant dynamics behind the $ΔI=1/2$ rule. However, the recent inclusion of lowest-lying vector meson contributions in addition to the pseudoscalar ones to hadronic matrix elements of current-current operators and the calculation of the corresponding Wilson coefficients in a momentum scheme at the NLO improved significantly the matching between quark-gluon short distance contributions and meson long distance contributions over our results in 1986. We obtain satisfactory description of the ${\rm Re}A_2$ amplitude and ${\rm Re}A_0/{\rm Re}A_2=16.0\pm 1.5$ to be compared with its experimental value of $22.3$. While this difference could be the result of present theoretical uncertainties in our approach, it cannot be excluded that New Physics (NP) is here at work. The analysis by Fulvia De Fazio, Jennifer Girrbach-Noe and myself shows that indeed a tree-level $Z^\prime$ or $G^\prime$ exchanges with masses in the reach of the LHC and special couplings to quarks can significantly improve the theoretical status of the $ΔI=1/2$ rule. I stress that our approach allows to understand the physics behind recent numerical results obtained in lattice QCD not only for the $ΔI=1/2$ rule but also for the parameter $\hat B_K$ that enters the evaluation of $\varepsilon_K$. In contrast to the $ΔI=1/2$ rule the chapter on $\hat B_K$ in QCD appears to be basically closed.
Revisiting f_B and m_b(m_b) from HQET spectral sum rules
利用表1中给出的QCD（非）微扰参数的最新值，我们重新考虑从N2 LO PT系列已知的HQET Laplace谱求和规则中提取f_B和壳层上质量M_b，并包括OPE中的7维凝聚。我们特别研究了PT级数的收敛性，连续阈值和减法点对“不同谱和规则数据”的影响在比现有文献更大的范围内变化，并在误差中包括基于PT级数几何增长的N3 LO PT级数的估计。我们得到了重整化群不变量（RGI）普适耦合：\hat f_B^ \infty =0.416（60）GeV^{3/2}（在静态极限M_PDMATHABMO \infty下）和包含1/M_b修正的物理衰变常数：f_B^{hqet}=199（29）MeV.利用求和比规则，我们得到α_s^2阶的运行质量m_b（m_b）=4213（59）MeV。与全QCD谱求和规则（QSSR）在同一通道上得到的相同阶数的结果：f_B^{qcd}=206（7）MeV，m_b（m_b）^{qcd}=4236（69）MeV一致.
Determination of $B$-meson distribution amplitudes from $B\to π,K,D$ transition form factors
Lanzhou University（兰州大学）；Institute of High Energy Physics, CAS（中国科学院高能物理研究所）；University of Chinese Academy of Sciences（中国科学院大学）；Universität Bonn（波恩大学）；Forschungszentrum Jülich（于利希研究中心）；Beihang University（北京航空航天大学）
Lattice-QCD validation of hadron mass and trace-anomaly decomposition sum rules
Scientific Computing Core, Flatiron Institute（科学计算核心，Flatiron研究所）；Key Laboratory of Quark & Lepton Physics (MOE) and Institute of Particle Physics, Central China Normal University（夸克与轻子物理教育部重点实验室和粒子物理研究所，华中师范大学）；Physics Department, Brookhaven National Laboratory（物理学系，布鲁海文国家实验室）
