Narrow Results

We present a model-independent analysis of CP violation, inspired by recent experimental observations, in charmed meson decays. The topological diagram approach is used to study direct CP asymmetries for singly Cabibbo-suppressed two-body hadronic decays of charmed mesons. We extract the magnitudes and relative phases of the corresponding topological amplitudes from available experimental information. In order to get more precise and reliable estimates of direct CP asymmetries, we take into account contributions from all possible strong penguin amplitudes, including the internal $b$-quark penguin contributions. We also study flavor SU(3) symmetry breaking effects in these decay modes and consequently predict direct CP asymmetries of unmeasured modes.

By using the 3-point QCD sum rules, we calculate the transition form factors of $D$ decays into the spin triplet axial vector mesons $a_1(1260)$, $f_1(1285)$, $f_1(1420)$. In the calculations, we consider the quark contents of each meson in detail. In view of the fact that the isospin of $a_1(1260)$ is one, we calculate the $D^{+}\to a_1^0(1260)$ and $D^0\to a_1^{-}(1260)$ transition form factors separately. In the case of $f_1(1285)$, $f_1(1420)$, the mixing between light flavor $SU(3)$ singlet and octet is taken into account. Based on the form factors obtained here, we give predictions for the branching ratios of relevant semileptonic decays, which can be tested in the future experiments.

The aim of this work is to provide a phenomenological analysis of the contribution of $D^0$ meson to $f_0(980){\pi }^{+}{\pi }^{-}(f_0(980)\to {\pi }^{+}{\pi }^{-})$, $K^{+}{K}^{-}{\bar{K}}^{\ast }{(982)}^0({\bar{K}}^{\ast }{(982)}^0\to {\pi }^{+}{K}^{-})$ and $\varphi {({\pi }^{+}{\pi }^{-})}_{S\text{-wave}}(\varphi \to K^{+}{K}^{-})$ quasi-three-body decays. Such that the analysis of mentioned four-body decays is summarized into three-body decay and several channels are observed. Based on the factorization approach, hadronic three-body decays receive both resonant and nonresonant contributions. We compute both contributions of three-body decays. As, there are tree, penguin, emission, and emission annihilation diagrams for these decay modes. Our theoretical model for $D^0\to \varphi {(\pi \pi )}_{S\text{-wave}}$ decay is based on the QCD factorization to quasi-two body followed by $S$-wave. This model for this decay following experimental information which demonstrated two pion interaction in the $S$-wave is introduced by the scalar resonance. The theoretical values are $(1.82\pm 0.24)\times 10^{-4}$, $(4.46\pm 0.41)\times 10^{-5}$ and $(1.1\pm 0.18)\times 10^{-4}$, while the experimental results of them are $(1.8\pm 0.5)\times 10^{-4}$, $(4.4\pm 1.7)\times 10^{-5}$ and $(2.5\pm 0.33)\times 10^{-4}$, respectively. Comparing computation analysis values with experimental values show that our results are in agreement with them.

Open-charmed mesons are unique tools to study the properties of the Quark–Gluon Plasma (QGP) formed in ultra-relativistic nucleus–nucleus collisions. The nuclear modification factor ($R_{\mathrm{\text{AA}}}$) and elliptic flow ($v_2$) of ${\mathrm{\text{D}}}^0$, ${\mathrm{\text{D}}}^{+}$, ${\mathrm{\text{D}}}^{\ast +}$, and ${\mathrm{\text{D}}}_{\mathrm{\text{s}}}^{+}$ mesons were measured by the ALICE Collaboration in Pb–Pb collisions at $\sqrt{s_{\mathrm{\text{NN}}}}=5.02$TeV. The D-meson $R_{\mathrm{\text{AA}}}$ provides information on the charm-quark interactions with the medium and the charm-quark energy loss. The D-meson elliptic flow at low transverse momentum ($p_{\mathrm{\text{T}}}$) gives insight into the participation of charm quarks in the collective expansion of the system and their possible in-medium thermalization. At high $p_{\mathrm{\text{T}}}$, the $v_2$ is sensitive to the path-length dependence of parton energy loss. The role of the recombination mechanism is investigated measuring the $p_{\mathrm{\text{T}}}$-differential yield ratios between D-meson species with and without strange-quark content. Finally, the coupling of charm quarks to light quarks of the underlying medium is examined applying the Event-Shape Engineering (ESE) technique to the nonstrange D-meson elliptic flow.

A brief review on the theoretical status of hadronic charm decays is presented. We emphasize the analyses based on the diagrammatic approach and the connection of weak annihilation with final-state rescattering. The topics on the mixing and the baryonic charm decay are sketched.