arXiv subjects

Ya-Xiong Wang

Publications and source records attributed to Ya-Xiong Wang.

8 recordsLinked to original sources

arXiv2026

Characterize the properties of $D_s^+$-meson decay constant and leptonic decays by using QCD sum rules within background field theory framework

The leptonic decays of the $D_s^+$-meson have received considerable attention in recent years. In this work, we perform a precise calculation of the decay constant $f_{D_s^+}$ using the QCD sum rules method within the background field theory framework. In our calculation, we fully include the quark propagator contributions up to dimension-six condensates. By adopting two different constraint schemes, we obtain $f_{D_s^+}^{\text{(I)}} = 253.0_{-3.1}^{+3.3}\ \text{MeV}$ and $f_{D_s^+}^{\text{(II)}} = 251.8_{-1.3}^{+1.4}\ \text{MeV}$, respectively, both of which are in good agreement with existing theoretical and experimental results. The conventional scheme follows the standard Borel window criteria, while the derivative scheme reduces the dependence of the decay constant on the Borel parameter through an auxiliary function. Based on these decay constants and incorporating the NLO electroweak radiative corrections, we further calculate the branching fractions for the three leptonic decay channels for both schemes. Combined with the latest branching fraction $\mathcal{B}(D_s^+ \to μ^+ ν_μ)$ from the PDG, we extract the CKM matrix elements $|V_{cs}|^{\text{(I)}} = 0.967 \pm 0.012$ and $|V_{cs}|^{\text{(II)}} = 0.970 \pm 0.005$ from the two schemes, respectively.

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arXiv2026

Vector mesons leading-twist longitudinal distribution amplitudes and related semi-leptonic decays within QCD sum rules

In this work, we focus on the light vector meson leading-twist longitudinal distribution amplitudes (DAs) $ϕ^\parallel_{2;V}(x,μ)$ with $V = ρ, K^\ast, ϕ$. In order to obtain their accurate behaviors, a new scheme of QCD sum rule research with respect to DA suggested in 2021 by us is adopted. With an improved sum rule formula, the $ξ$-moments $\langleξ^n\rangle_{2;V}^\parallel$ up to tenth order are calculated. In which, $\langleξ^2\rangle^\parallel_{2;ρ}=0.225^{+0.013}_{-0.012}$, $\langleξ^1\rangle^\parallel_{2;K^\ast}=-0.0228^{+0.0042}_{-0.0040}$, $\langleξ^2\rangle^\parallel_{2;K^\ast}=0.217^{+0.007}_{-0.007}$, $\langleξ^2\rangle^\parallel_{2;ϕ}=0.209^{+0.020}_{-0.020}$, and the corresponding Gegenbauer moments $a^{2;\parallel}_{2;ρ}=0.074^{+0.039}_{-0.036}$, $a^{1;\parallel}_{2;K^\ast}=-0.038^{+0.007}_{-0.007}$, $a^{2;\parallel}_{2;K^\ast}=0.050^{+0.020}_{-0.019}$, $a^{2;\parallel}_{2;ϕ}=0.027^{+0.058}_{-0.058}$ at the scale $μ= 1~{\rm GeV}$, respectively. By fitting those $\langleξ^n\rangle^\parallel_{2;V}(n = 1,2,\cdots,10)$ with the least squares method, the behaviors of leading-twist longitudinal DAs for $ρ, K^\ast, ϕ$ are determined. Further, we recalculate the transition form factors and branching ratio of the $D\to(ρ,K^\ast)$, $D_s\toϕ$ semi-leptonic decay processes.

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arXiv2025

Status of the $D_s^+\toϕ\ell^+ν_\ell$ decay with a chiral-odd $ϕ$-meson light-cone distribution amplitude

The twist-2 distribution amplitude of the $ϕ$-meson has attracted considerable interest due to its unique properties. In this work, we construct the transverse leading-twist light-cone distribution amplitude $ϕ_{2;ϕ}^\bot(x,μ_0)$ of the $ϕ$-meson using the light-cone harmonic oscillator model, in which a parameter $B_{2;ϕ}^\bot$ dominantly control its longitudinal distribution. To explicitly isolate different twist contributions, we employ the right-handed chiral correlator for the QCD light-cone sum rules calculation of $D_s^+\toϕ$ decays, and further, we get the branching fraction, $\mathcal{B}(D_s^+ \to ϕe^+ν_e )= (2.271_{-0.243}^{+0.291})\times 10^{-2}$ and $\mathcal{B}(D_s^+ \to ϕμ^+ν_μ)=(2.250_{-0.240}^{+0.287})\times 10^{-2}$, where errors are squared average of the mentioned error sources. Furthermore, we have extracted the Cabbibo-Kobayashi-Maskawa (CKM) matrix element $|V_{cs}|=0.975_{-0.066}^{+0.067}$ with improved precision through the analysis. Finally, we calculated the polarization parameter and asymmetry parameter for the $D_s^+\toϕ$ decays.

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arXiv2025

Probing $D_s^*$-meson longitudinal twist-2 LCDA

In this paper, we carry on an investigation of the semileptonic decays $B_s\to D_s^*\ell \barν_{\ell}$. Firstly, we derive the moments of the $D_s^*$-meson longitudinal leading-twist light-cone distribution amplitude (LCDA) based on QCD sum rules within background field theory framework. Considering the contributions of the vacuum condensates up to dimension-six, its first ten non-zero $ξ$-moments are given. Meanwhile, we construct the $D_s^*$-meson longitudinal leading-twist LCDA by using the light-cone harmonic oscillator model. Then, using those moments, we fix the model parameters $α_{2;D_s^*}$ and $B_1^{2;D_s^*}$ by the least square method and apply them to calculate $B_s \to D_s^*$ transition form factors $A_1(q^2), A_2(q^2)$ and $V(q^2)$ that are derived by using the QCD light-cone sum rules. At the large recoil region, we obtain $A_1(0) =0.632_{-0.135}^{+0.228}, A_2(0) =0.706_{-0.092}^{+0.109}$ and $V(0) =0.647_{-0.069}^{+0.076}$. Those form factors are then extrapolated to the allowed whole physical $q^2$-region through the simplified series expansion. Finally, we obtain the branching fractions for the two decay channels $B_s\to D_s^*\ell\barν_\ell$, $\it i.e.$ ${\cal B}(B_s^0 \to D_s^{*+}e^-\barν_e)=(5.45_{-1.57}^{+2.15})\times 10^{-2}$, ${\cal B}(B_s^0 \to D_s^{*+}μ^-\barν_μ)=(5.43_{-1.57}^{+2.14})\times 10^{-2}$.

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arXiv2025

Probing $|V_{cs}|$ and lepton flavor universality through $D\to K_0^\ast(1430)\ellν_{\ell}$ decay

In this paper, we calculate the semileptonic decays $D\to K_0^\ast(1430)\ellν_{\ell}$ with $\ell=(e,μ)$ induced by $c\to s\ellν_{\ell}$ transition. For the key component, $D\to K_0^\ast(1430)$ transition form factors (TFFs) $f_{\pm}(q^2)$ are calculated within the framework of QCD light cone sum rule. Then, we consider two scenarios for $K_0^\ast(1430)$-meson twist-2 distribution amplitude. For the scenario 1 (S1), we take the truncated form based on Gegenbauer polynomial series. Meanwhile, we also consider the scenario 2 (S2) constructed by light cone harmonic oscillator model, where the model parameters are fixed by the $K_0^\ast(1430)$-meson twist-2 distribution amplitude tenth-order $ξ$ moments calculated by using the background field theory. For the TFFs at a large recoil point, we have $f_+^{\rm (S1)}(0)=0.597^{+0.122}_{-0.121}$ and $f_-^{\rm (S1)}(0)=-0.136^{+0.023}_{-0.035}$, $f_+^{\rm (S2)}(0)= 0.663^{+0.135}_{-0.134}$, and $f_-^{\rm (S2)}(0)=-0.202^{+0.026}_{-0.046}$. After extrapolating TFFs to the whole physical $q^2$ region, we calculate the branching fractions of $D^0\to K_0^{\ast +}(1430)\ell^-\barν_\ell$ and $D^+\to K_0^{\ast 0}(1430)\ell^+ν_\ell$, which at $10^{-4}$-order level for the S1 and S2 cases. Meanwhile, we predict the CKM matrix $|V_{cs}|^{\rm (S1)}=0.973^{+0.259}_{-0.183}, |V_{cs}|^{\rm (S2)}=0.880^{+0.234}_{-0.165}$, and lepton flavor universality $\mathcal{R}^{\rm (S1)}_{K_0^*}=0.768^{+0.560}_{-0.368}, \mathcal{R}_{K_0^*}^{\rm (S2)}=0.764^{+0.555}_{-0.365}$. Finally, we discuss the angular observables of forward-backward asymmetries, lepton polarization asymmetries, and $q^2$-differential flat terms for this decay.

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arXiv2024

The rare decay $B^+ \to K^+\ell^+\ell^-(ν\barν)$ under the QCD sum rules approach

In the paper, we conduct a detailed investigation of the rare decay processes of charged meson, specifically $B^+ \to K^+\ell^+\ell^-$ with $\ell=(e,μ,τ)$ and $B^+ \to K^+ν\barν$. These processes involve flavor-changing-neutral-current (FCNC) transitions, namely $b\to s\ell^+\ell^-$ and $b\to sν\barν$. The essential components $B\to K$ scalar, vector and tensor transition form factors (TFFs) are calculated by using the QCD light-cone sum rules approach up to next-to-leading order QCD corrections. In which, the kaon twist-2 and twist-3 light-cone distribution amplitudes are calculated from both the QCD sum rules within the framework of background field theory and the light-cone harmonic oscillator model. The TFFs at large recoil point are $f_+^{BK}(0)=f_0^{BK}(0) =0.328_{-0.028}^{+0.032}$ and $f_{\rm T}^{BK}(0)=0.277_{-0.024}^{+0.028}$, respectively. To achieve the behavior of those TFFs in the whole $q^2$-region, we extrapolate them by utilizing the simplified $z(q^2)$-series expansion. Furthermore, we compute the differential branching fractions with respect to the squared dilepton invariant mass for the two different decay channels and present the corresponding curves. Our predictions of total branching fraction are ${\cal B}(B^+\to K^+ e^+ e^-)=6.633_{-1.070}^{+1.341}\times 10^{-7}$, ${\cal B}(B^+\to K^+ μ^+ μ^-)=6.620_{-1.056}^{+1.323}\times 10^{-7}$, ${\cal B}(B^+\to K^+ τ^+ τ^-)=1.760_{-0.197}^{+0.241}\times 10^{-7}$, and ${\cal B}(B^+\to K^+ ν\barν)=4.135_{-0.655}^{+0.820}\times 10^{-6}$, respectively. Lastly, the observables such as the lepton universality $\mathcal{R}_{K}$ and the angular distribution `flat term' $F_{\rm H}^\ell$ are given, which show good agreement with the theoretical and experimental predictions.

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arXiv2024

Prospective analysis of CKM element $|V_{cd}|$ and $D^+$-meson decay constant from leptonic decays $D^+ \to \ell^+ ν$

The leptonic decay of $D^+$-meson has attracted significant interest due to its unique characteristics. In this paper, we carry out an investigation into the $D^+$-meson leptonic decays $D^+\to \ell^+ν_{\ell}$ with $\ell=(e,μ,τ)$ by employing the QCD sum rules approach. In which the $D^+$-meson decay constant $f_{D^+}$ is an important input parameter in the process. To enhance the accuracy of our calculations for $f_{D^+}$, we consider the quark propagator and vertex up to dimension-six within the framework of background field theory. Consequently, we obtain the QCD sum rule expression for $f_{D^+}$ up to dimension-six condensates, yielding $f_{D^+}=203.0\pm1.5~\mathrm{MeV}$. Our results are in good agreement with BESIII measurements and theoretical predictions. We also present the integrated decay widths for the $D^+$-meson in three channels $Γ(D^+\to e^+ν_e)=(5.263_{-0.075}^{+0.076})\times10^{-21}~\mathrm{GeV}$, $Γ(D^+\to μ^+ν_μ)=(2.236_{-0.032}^{+0.032})\times10^{-16}~\mathrm{GeV}$ and $Γ(D^+\to τ^+ν_τ)=(5.958_{-0.085}^{+0.086})\times10^{-16}~\mathrm{GeV}$. Accordingly, we compute the branching fraction $\mathcal{B}(D^+\to\ell^+ν_{\ell})$ with the electron, muon and tau channels, which are $\mathcal{B}(D^+\to e^+ν_e)=(8.260_{-0.118}^{+0.119})\times10^{-9}$, $\mathcal{B}(D^+\toμ^+ν_μ)=(3.508_{-0.050}^{+0.051})\times10^{-4}$ and $\mathcal{B}(D^+\toτ^+ν_τ)=(0.935_{-0.013}^{+0.013})\times10^{-3}$. Furthermore, we present our prediction for the CKM matrix element $|V_{cd}|$ using the branching fraction $\mathcal{B}(D^+\toμ^+ν_μ)$ obtained from BESIII Collaboration, yielding $|V_{cd}|=0.227_{-0.001}^{+0.002}$.

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arXiv2024

Scrutinizing $B^0$-meson flavor changing neutral current decay into scalar $K_0^*(1430)$ meson with $b\to s \ell^+\ell^-(ν\barν)$ transition

In this paper, we investigate the rare decay $B^0\to K_0^*(1430)\ell^+\ell^-$ with $\ell=(e,μ,τ)$ and $B^0\to K_0^*(1430)ν\barν$ induced by the flavor changing neutral current transition of $b\to s\ell^+\ell^-(ν\barν)$. Firstly, the $B^0\to K_0^*(1430)$ transition form factors (TFFs) are calculated by using the QCD light-cone sum rule approach up to next-to-leading order accuracy. In which the $K_0^*(1430)$-meson twist-2 and twist-3 LCDAs have been calculated both from the SVZ sum rule in the background field theory framework and light-cone harmonic oscillator model. Then, we obtained the three TFFs at large recoil point, {\it i.e.,} $f_+^{B^0\to K_0^\ast}(0)= 0.470_{-0.101}^{+0.086}$, $f_-^{B^0\to K_0^\ast}(0)= -0.340_{-0.068}^{+0.068}$, and $f_{\rm T}^{B^0\to K_0^\ast}(0)= 0.537^{+0.112}_{-0.115}$. Meanwhile, we extrapolated TFFs to the whole physical $q^2$-region by using the simplified $z(q^2)$-series expansion. Furthermore, we calculate the $B^0\to K_0^*(1430)\ell^+\ell^-(ν\barν)$ decay widths, branching fractions, and longitudinal lepton polarization asymmetries of $B^0\to K_0^*(1430)\ell^+\ell^-$, which lead to ${\cal B}(B^0\to K_0^*(1430)e^+e^-) = (6.65^{+2.52}_{-2.42})\times 10^{-7}$, ${\cal B}(B^0\to K_0^*(1430)μ^+μ^-)=(6.62^{+2.51}_{-2.41})\times 10^{-7}$, ${\cal B}(B^0\to K_0^*(1430)τ^+τ^-)=(1.88^{+1.10}_{-0.97})\times 10^{-8}$, ${\cal B}(B^0\to K_0^*(1430)ν\barν)= 3.85^{+1.55}_{-1.48}\times 10^{-6}$ and the integrated longitudinal lepton polarization asymmetries $\langle A_{P_L} \rangle = (-0.99, -0.96, -0.03)$ for the cases $\ell=(e, μ, τ)$ respectively.

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