arXiv subjects

Yi-Peng Xing

Publications and source records attributed to Yi-Peng Xing.

4 recordsLinked to original sources

arXiv2026

From QCD sum rules to HQET sum rules: Heavy-quark limit of four-quark operator matrix elements

Heavy quark expansion theory provides the standard theoretical framework for understanding the lifetimes of weakly decaying heavy-flavor hadrons. Within this framework, the matrix elements of four-quark operators play a crucial role in explaining the lifetime differences among hadrons containing the same heavy quark. In this work, we calculate these matrix elements at leading order using full QCD sum rules, with particular emphasis on deriving the corresponding HQET sum rules by taking the heavy-quark limit. While this limit is straightforward for most contributions, it turns out to be rather nontrivial for certain ones. Numerical analyses show that the results obtained from the two approaches are consistent with each other. We further clarify the origin of the large discrepancies reported in the literature between full QCD sum rule and HQET sum rule results. This work contributes to a deeper understanding of the relationship between the two sum-rule approaches and is expected to facilitate future applications of QCD and HQET sum rules in the study of heavy-flavor hadrons. The findings presented here may be of interest to both practitioners of QCD sum rules and researchers working on effective field theories.

hep-ph↗

arXiv2025

Semileptonic $s\to u$ decays of singly heavy baryons

$s\to u$ weak decays of heavy flavor hadrons play a unique role in the field of heavy flavor physics. In this work, we investigate semileptonic $s\to u$ decays of singly heavy baryons in the light-front approach under the three-quark picture. Firstly, we provide all the form factors using this quark model, especially for $f_{3}$ and $g_{3}$, which are usually considered non-extractable in recent literature. We also discuss the heavy quark limit for the form factors, and some of our results differ from those in the literature. We find that, when considering the heavy quark limit, the $m_{s}$ correction may not be negligible. Secondly, we apply the obtained form factors to predict some observables in semileptonic decays. It is worth noting that, due to the extremely small phase space, lepton flavor universality (LFU) is sensitive to the masses of leptons, and precise measurement of LFU is expected to be an important tool for testing the standard model.

hep-ph↗

arXiv2024

A progress in inverse matrix method in QCD sum rules

In traditional QCD sum rules, the simple hadron spectral density model of ``delta-function-type ground state + theta-function-type continuous spectrum" determines that there is no perfect parameter selection. In recent years, inverse problem methods, especially the inverse matrix method, have shown better handling of QCD sum rules. This work continues to develop the inverse matrix method. Considering that the narrow-width approximation may still be a good approximation, we separate the contribution of the ground state from the spectral density. Then follow the general steps of the inverse matrix method to extract physical quantities such as decay constants that we are sometimes more interested in.

hep-ph↗

arXiv2023

Semi-leptonic form factors of $Ξ_{c}\toΞ$ in QCD sum rules

There exists a significant deviation between the most recent Lattice QCD simulation and experimental measurement by Belle for $Ξ_{c}^{0}\toΞ^{-}\ell^{+}ν_{\ell}$. In this work, we investigate the $Ξ_{c}\toΞ$ form factors in QCD sum rules. To this end, the two-point correlation functions of $Ξ_{c}$ and $Ξ$, and the three-point correlation functions of $Ξ_{c}\toΞ$ are calculated. At the QCD level, contributions from up to dimension-6 four-quark operators are considered, and the leading order results of the Wilson coefficients are obtained. For the form factors, relatively stable Borel windows can be found. Our form factors are comparable with those of Lattice QCD, except for $f_{\perp}$. The obtained form factors are then used to predict the branching ratios of $Ξ_{c}\toΞ\ell^{+}ν_{\ell}$, and our predictions are consistent with the most recent data of ALICE and Belle, and those of Lattice QCD within error. Given that the branching ratios only contain limited information, we suggest the experimentalists directly measure the form factors of $Ξ_{c}\toΞ$.

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