Analysis of the semileptonic decays $\hat{I}{\pounds }_b\to \hat{I}{\pounds }_{c}l\bar{\hat{I}}{½}_l$, $\hat{I}{ž}_b^{\prime }\to \hat{I}{ž}_c^{\prime }l\bar{\hat{I}}{½}_l$ and $\hat{I}{\text{c◯}}_b\to \hat{I}{\text{c◯}}_{c}l\bar{\hat{I}}{½}_l$ in QCD sum rules

Abstract

In this article, the electroweak transition form factors of $\hat{I}{\pounds }_b\to \hat{I}{\pounds }_c$, $\hat{I}{ž}_b^{\prime }\to \hat{I}{ž}_c^{\prime }$ and $\hat{I}{\text{c◯}}_b\to \hat{I}{\text{c◯}}_c$ are analyzed within the framework of three-point QCD sum rules. In phenomenological side, all possible couplings of interpolating current to hadronic states are considered, and the Dirac structure dependence on the form factors is systematically eliminated. In QCD side, our calculation incorporates both the perturbative part and the contributions from vacuum condensates up to dimension 8. This systematic inclusion of higher-dimensional terms accounts for a broader set of Feynman diagrams, thereby enhancing the comprehensiveness and reliability of the operator product expansion. Using the obtained form factors, we study the partial widths of semileptonic decays $\hat{I}{\pounds }_b\to \hat{I}{\pounds }_{c}l\bar{\hat{I}}{½}_l$, $\hat{I}{ž}_b^{\prime }\to \hat{I}{ž}_c^{\prime }l\bar{\hat{I}}{½}_l$ and $\hat{I}{\text{c◯}}_b\to \hat{I}{\text{c◯}}_{c}l\bar{\hat{I}}{½}_l$ ($l=e$, $\hat{I}¼$ and $\ddot{I}„$). The results indicate that these decay widths approximately satisfy SU(3) flavor symmetry. Next, we calculate the branching ratios for the decay process $\hat{I}{\text{c◯}}_b\to \hat{I}{\text{c◯}}_{c}l\bar{\hat{I}}{½}_l$ and compare them with the results from other collaborations. Furthermore, the lepton universality ratios and some asymmetry parameters of these decay processes are also analyzed, which provide information for the study of new physics. We hope that these results will serve as a useful reference for future theoretical and experimental studies of weak decays involving heavy flavor baryons.

22 pages, 12 figures