arXiv subjects

Ya-Lin Song

Publications and source records attributed to Ya-Lin Song.

4 recordsLinked to original sources

arXiv2026

$a_0(1450)$-state twist-2 light-cone distribution amplitude moments within QCD sum rules and its implication in $\bar B^0\to a_0(1450)^+\ell^-\bar\nu_\ell$ decays

Based on longstanding puzzle for the structure of light scalar meson, it is meaningful to make a deep research for its property in different decay processes especially in the bottom meson semileptonic decays. The current experimental and theoretical predictions are inclined to the quark-antiquark state in $B$-decays, which is also the basic starting point of this work. Firstly, the first five-order $a_0(1450)$-state leading-twist distribution amplitude $\xi$-moments are calculated by using the QCD sum rule within background field theory, which all the gluon-condensate and quark-condensate are calculated up to full dimension-six accuracy. We present the their values up to nineth-order at initial scale. Then we construct $a_0(1450)$-state twist-2 LCDA with light-cone harmonic oscillator models as the scenario 1 (S1), where the model parameters are determined by fitting the first five odd $\xi$-moments using the least squares method. On the other hand, the truncated form of Gegenbauer polynomials expansion up to second-order is also considered as the scenario 2 (S2) to make a comparison, where the relationship between Gegenbauer moments and LCDA moments are considered. Subsequently, we calculated the $\bar{B}^0 \to a_0(1450)^+$ transition form factors (TFFs) by using the light-cone sum rules approach, incorporating contributions from both twist-2 and twist-3 LCDAs. By extrapolating TFFs to the entire physical $q^2$-region with simplified series expansion, the differential decay width and branching ratios for the $\bar B^0\to a_0(1450)^+\ell^-\bar\nu_\ell$ semileptonic decay are obtained. Finally, we present three angular observables including forward-backward asymmetry, lepton polarization asymmetry and $q^2$-differential flat term.

hep-ph↗

arXiv2025

Searching the possibility of $a_0(1450)$ scalar state being a diquark structure via charmed meson semileptonic decays

The internal structure of light scalar state $a_0(1450)$ has not been definitively determined, it may consist of multiple possible states. Among them, it has the possibility of being regarded as a diquark state. Based on this possibility, we use QCD light-cone sum rules to study the semileptonic decay process $D \to a_0(1450)\ell \nu_\ell $ with $\ell=(e, \mu)$ to verify its rationality. Firstly, we construct two types of twist-2 light-cone distribution amplitude schemes based on the light-cone harmonic oscillator model, and present their moments $\langle\xi^{n}\rangle |_{\mu}$ and Gegenbauer moments $a_{n}(\mu)$ at $\mu_0=1~{\rm GeV}$ and $\mu_k= 1.4~{\rm GeV}$ for $n=(1,3,5)$. In the large recoil region, we obtain the transition form factors (TFFs): $f_+^{\rm (S1)}(0) = 0.836_{-0.116}^{+0.119}$, $f_+^{\rm (S2)}(0)=0.767_{-0.105}^{+0.106}$ and $f_-(0)=0.630_{-0.077}^{+0.078}$. A simplified series expansion $z(q^2, t)$ is used to extrapolate TFFs to the entire physical $q^2$-region. For $q^2=10^{-5} ~{\rm GeV}^2$, we compute angular distribution of the differential decay width ${d\Gamma}/{d\cos\theta_\ell }$ over the range $\cos\theta_\ell \in [-1,1]$. Subsequently, we obtain differential decay widths and branching fractions for $D^0 \to a_0(1450)^- \ell^+ \nu_\ell $ and $D^- \to a_0(1450)^0 \ell^- \bar{\nu}_\ell $, where the branching fractions being of order $10^{-6}$. Finally, we analyze three angular observables for the semileptonic decay process $D^- \to a_0(1450)^0 \ell^- \bar{\nu}_\ell $, the forward-backward asymmetry ${\cal A}_{\rm FB}$, lepton polarization asymmetry ${\cal A}_{\lambda_\ell}$ and $q^2$-differential flat term~${\cal F}_{\rm H}$.

hep-ph↗

arXiv2025

Exploring the exclusive decay $B^+\to \omega\ell^+\nu$ with light-cone sum rules

In this paper, we calculate the Cabibbo-Kobayashi-Maskawa matrix element $|V_{ub}|$ by the semileptonic decay $B^+\to \omega\ell^+\nu$. For the transition form factors (TFFs) $A_1(q^2)$, $A_2(q^2)$, and $V(q^2)$ of $B^+\to \omega$, we employ the QCD light-cone sum rules method for calculation, and by constructing the correlation function using left-handed chiral current, we make the $\delta^1$-order twist-2 light-cone distribution amplitudes (LCDA) $\phi^\| _{2;\omega}(x,\mu)$ dominate the contribution, in which the twist-2 LCDA $\phi^\| _{2;\omega}(x,\mu)$ is constructed by the light-cone harmonic oscillator model. Then, we obtain $A_1(0)=0.209^{+0.049}_{-0.042}$, $A_2(0)=0.206^{+0.051}_{-0.042}$, and $V(0)=0.258^{+0.058}_{-0.048}$ at the large recoil region. Two important ratios of TFFs are $r_V=1.234_{-0.322}^{+0.425}$ and $r_2=0.985_{-0.274}^{+0.347}$. After extrapolating TFFs to the whole physical $q^2$ region by a simplified $z(q^2,t)$-series expansion, we obtain the differential decay width and branching fraction $\mathcal{B}(B^+\to \omega\ell^+\nu)=(1.35^{+0.02+1.22}_{-0.03-0.66})\times 10^{-4}$, which show good agreement with \textit{BABAR} and Belle Collaborations. Finally, we extract the $|V_{ub}|$ by using the $\mathcal{B}_{\rm{Exp}}(B^+\to \omega\ell^+\nu)$ result from the \textit{BABAR} Collaboration, which leads to $|V_{ub}|=(3.66^{+0.12+1.26}_{-0.17-0.95})\times 10^{-3}$.

hep-ph↗

arXiv2024

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

In this paper, we investigate the rare decay $B^0\to K_0^*(1430)\ell^+\ell^-$ with $\ell=(e,\mu,\tau)$ and $B^0\to K_0^*(1430)\nu\bar{\nu}$ induced by the flavor changing neutral current transition of $b\to s\ell^+\ell^-(\nu\bar\nu)$. 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 $B^0\to K_0^*(1430)\ell^+\ell^-(\nu\bar{\nu})$ decay widths, branching fractions, and longitudinal lepton polarization asymmetries of $B^0\to K_0^*(1430)\ell^+\ell^-$, which lead to ${\cal B}(B^0\to K_0^*(1430)e^+e^-) = (6.65^{+2.52}_{-2.42})\times 10^{-7}$, ${\cal B}(B^0\to K_0^*(1430)\mu^+\mu^-)=(6.62^{+2.51}_{-2.41})\times 10^{-7}$, ${\cal B}(B^0\to K_0^*(1430)\tau^+\tau^-)=(1.88^{+1.10}_{-0.97})\times 10^{-8}$, ${\cal B}(B^0\to K_0^*(1430)\nu\bar{\nu})= 3.85^{+1.55}_{-1.48}\times 10^{-6}$ and the integrated longitudinal lepton polarization asymmetries $\langle A_{P_L} \rangle = (-0.99, -0.96, -0.03)$ for the cases $\ell=(e, \mu, \tau)$ respectively.

hep-ph↗