Our 2003 "Cicerone" had discussed charm dynamics with different directions and levels \cite{CICERONE}. Here we focus on two items, where the `landscape' has changed sizably. (A) The lifetimes \& semi-leptonic decays of charm hadrons show the impact of non-perturbative QCD and to which degree one can apply Heavy Quark Expansion (HQE) for charm hadrons. It is more complex as we have learnt from 2019/20 data. (B) {\bf CP} asymmetry has been established in 2019 \cite{LHCbGuy}: $ΔA_{\bf CP} \equiv A_{\bf CP}(D^0 \to K^+K^-) - A_{\bf CP}(D^0 \to π^+π^-) $=$\, -\, (1.54 \pm 0.29 ) \cdot 10^{-3}$ is quite an achievement by the LHCb collaboration! Our community is at the beginning of a long travel for fundamental dynamics. Can the SM account for these? We discuss the assumptions that were made up to 2018 data and new conclusions from 2019/20 ones. We need more data; however, one has to discuss correlations between different transitions. We give an {\bf Appendix} what we have learnt for large {\bf CP} asymmetry in $K_L \to π^+π^-e^+e^-$.
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) …
A novel observable measuring the $C\!P$ asymmetry in multi-body decays of heavy mesons, which is called the forward-backward asymmetry induced $C\!P$ asymmetry (FBI-$C\!P$A), $A_{CP}^{FB}$, is introduced. This observable has the dual advantages that 1) it can isolate the $C\!P$ asymmetry associated with the interference of the $S$- and $P$-wave amplitude from that associated with the $S$- or $P$-wave amplitude alone; 2) it can effectively almost double the statistics comparing to the conventionally defined regional $C\!P$ asymmetry. We also suggest to perform the measurements of FBI-$C\!P$A in…
A model for the $B^\pm \to π^-π^+π^\pm$ decay amplitude is proposed to study the large CP violation observed at the high mass region of the Dalitz plane. A short distance $ b \to u $ amplitude with the weak phase $γ$ is considered together with the contribution of a hadronic charm loop and a s-wave $D\bar{D}\to ππ$ rescattering. In the model, the $χ_c^0$ appears as a narrow resonant state of the $D\bar D$ system below threshold. It is introduced in an unitary two channel S-matrix model of the coupled $D\bar D$ and $ππ$ channels, where the $χ_c^0$ complex pole in $D\bar D$ channel shows its sig…
I discuss the calculation of the direct CP-asymmetry in $D\to π^+π^-$ and $D\to K^+K^- $ decays with the method of QCD light-cone sum rules. The main result is the upper limit for the difference of the two asymmetries $\left|Δa_{CP}^{dir}\right| < 0.020\pm 0.003\%$ which is significantly smaller than the recent measurement of this quantity by the LHCb collaboration
Direct CP violation in two-body $D\to PP$ and $D\to V\!P$ decays is studied within the framework of the topological amplitude approach for tree amplitudes and the QCD factorization approach for penguin amplitudes. It is the interference between tree and long-distance penguin and penguin-exchange amplitudes that pushes CP asymmetry difference between $D^0\to K^+K^-$ and $π^+π^-$ modes up to the per mille level. Using the same mechanism, we find that CP asymmetry can also occur at the $10^{-3}$ level in many of the $D\to V\!P$ channels or otherwise be negligibly small. There are six golden modes…
We present the first lattice QCD calculation of the charm quark contribution to the nucleon electromagnetic form factors $G^c_{E,M}(Q^2)$ in the momentum transfer range $0\leq Q^2 \leq 1.4$ $\rm GeV^2$. The quark mass dependence, finite lattice spacing and volume corrections are taken into account simultaneously based on the calculation on three gauge ensembles including one at the physical pion mass. The nonzero value of the charm magnetic moment $μ^c_M=-0.00127(38)_{\rm stat}(5)_{\rm sys}$, as well as the Pauli form factor, reflects a nontrivial role of the charm sea in the nucleon spin stru…
Single Transverse-Spin Asymmetry in Open Charm Production in SIDIS
讨论了在半包容DIS（SIDIS），$e p^\uparrow \rightarrow e D X$中大横动量$D$介子产生中观察到的单横自旋不对称性。这种贡献体现为共线因子分解中的twist-3机制，它是由横极化核子内部的纯胶子关联，特别是三胶子关联效应引起的。我们导出了首阶QCD中相应SSA的第一个完整公式，揭示了产生的$D$介子的五种独立结构对方位角的依赖关系.我们的结果服从普遍的结构背后的SSA在各种硬过程。本文给出了与未来电子离子对撞机相关的运动学条件下$D$ -介子产生的SSA公式的数值计算。
Single Transverse-Spin Asymmetry in Large $P_T$ Open Charm Production at an Electron-Ion Collider
本文讨论了在半包容深度非弹性散射$e p^\uparrow \rightarrow e D X$中大横动量$D$介子产生中观察到的单横自旋不对称性。这种贡献体现为共线因子分解中的twist-3机制，它是由横极化核子内部的纯胶子关联，特别是三胶子关联效应引起的。用四个独立的胶子关联函数表示了首阶QCD中相应SSA的完整公式，并揭示了所产生的$D$ -介子的五种独立结构对方位角的依赖关系.本文给出了SSA公式在与未来电子离子对撞机相关的运动学上的数值计算。
We analyze rare charm baryon decays within the standard model and beyond. We identify all null test observables in unpolarized $Λ_c \to p \ell^+ \ell^-$, $\ell=e, μ$ decays, and study the new physics sensitivities. We find that the longitudinal dilepton polarization fraction $F_L$ is sensitive to electromagnetic dipole couplings $C_{7}^{(\prime)}$, and to the right-handed 4-fermion vector coupling $C_{9}^\prime$. The forward-backward asymmetry, $A_{\rm FB}$, due to the GIM-suppression a standard model null test already, probes the left-handed axialvector 4-fermion coupling $C_{10}$; its CP-asy…
In the wake of recent measurements of ratios of semileptonic branching fractions: ${\cal R}_{J/ψ}, {\cal R}_D$ and ${\cal R}_{D^*}$ reported by the LHCb, BELLE and HFLAV Collaborations, we calculate invariant form factors for the exclusive semileptonic $B_c$-meson decays to radially excited charmonium and charm meson states in the full kinematical region within the framework of relativistic independent quark (RIQ)model. We evaluate the lepton mass effect in the decay processes induced by $b\to c,u$ transition at the quark level. Our predictions on branching fractions for $B_c\to η_c/ψ(nS)$ are…
The reported CP asymmetry in D->K^+K^- / pi^+pi^- is argued to be too large to naturally fit the SM. If so, a new source of CP violation is implied in the Delta C=1 sector with a milliweak strength. CP-odd interactions in the flavor-diagonal sector are strongly constrained by the EDMs placing severe limitations on the underlying theory. While the largest effects usually come from the New Physics energy scale, they are strongly model-dependent. Yet the interference of the CP-odd forces manifested in D decays with the conventional CP-even Delta C=1 weak interaction generates at the charm scale a…
