与基于CKM三角形的全局拟合和一般理论预期的标准模型预期相比，非轻子b -> s衰变中分支分数和CP不对称性的精确测量揭示了某些“谜题”。在不参考特定模型的情况下，我们研究在（B -> J/psi K），（B -> phi K）和（B -> K pi）中观察到的（小）差异在多大程度上可能限制（b -> s q qbar）算子中的新物理。特别地，我们在定量水平上比较了不同夸克味q=c，s，u，d的相对影响。
英文摘要：
Precision measurements of branching fractions and CP asymmetries in non-leptonic b -> s decays reveal certain "puzzles" when compared with Standard Model expectations based on a global fit of the CKM triangle and general theoretical expectations. Without reference to a particular model, we investigate to what extent the (small) discrepancies observed in (B -> J/psi K), (B -> phi K) and (B -> K pi) may constrain new physics in (b -> s q qbar) operators. In particular, we compare on a quantitative level the relative impact of different quark flavours q=c,s,u,d.
Decay constants, semi-leptonic and non-leptonic decays in a Bethe-Salpeter Model
在Bethe-Salpeter模型中计算了B介子和$D$介子的衰变常数以及B介子到$D$和$D^*$介子的半轻子衰变的形状因子.从数据中，我们从${\bar B} \to D^* l {\barν} $中提取$V_{cb}=0.039 \pm 0.002$，从${\bar B} \to D l {\barν} $衰变中提取$V_{cb}=0.037 \pm 0.004$。然后使用形状因子在因子分解近似下获得$ B\to D π(K) $和$B \to D D (D_s) $的非轻子衰变部分宽度。
The QCD$\times$QED factorization is studied for two-body non-leptonic and semi-leptonic $B$ decays with heavy-light final states. These non-leptonic decays, like $\bar{B}^0_{(s)}\to D^+_{(s)} π^-$ and $\bar{B}_d^0 \to D^+ K^-$, are among the theoretically cleanest non-leptonic decays as penguin loops do not contribute and colour-suppressed tree amplitudes are suppressed in the heavy-quark limit or even completely absent. Advancing the theoretical calculations of such decays requires therefore also a careful analysis of QED effects. Including QED effects does not alter the general structure of …
The theoretical calculation of pseudo-scalar leptonic decay widths into an invisible ALP, $M \to \ell\, ν_\ell\, a$, is reviewed. Assuming generic flavour-conserving ALP couplings to SM fermions and a generic ALP mass, $m_a$, the latest experimental results for pseudo-scalar leptonic decays are used to provide updated bounds on the ALP-fermion Lagrangian sector. Constrains on the ALP-quark couplings obtained from these channels are not yet competitive with the ones derived from FCNC processes, like $M\to P\,a$ decays. These leptonic decays can, however, provide the most stringent model-indepen…
We consider a scenario with only one sterile neutrino $ N $, negligible mixing with the active neutrinos $ ν_{L} $, where its interactions with ordinary particles could be described in a model independent approach based on an effective theory. Under such a framwork, we consider the contributions of the sterile neutrino $N$ to the pure leptonic decays $ M \rightarrow lν$ and $ ν\overlineν $, and the radiative leptonic decays $ M \rightarrow lνγ$ with $M$ denoting the pseudoscalar mesons $ B $, $ D $ and $ K$. We find that it can produce significant effects on some of these rare decay processes.
We compute the contributions of dimension six two-quark operators to the non-leptonic decay width of heavy hadrons due to the flavor changing bottom-to-up-quark transition in the heavy quark expansion. Analytical expressions for the Darwin term $ρ_D$ and the spin-orbit term $ρ_{\rm LS}$ are obtained with leading order accuracy.
