arXiv subjects

Yan-Li Wang

Publications and source records attributed to Yan-Li Wang.

6 recordsLinked to original sources

arXiv2026

$CP$ violation in singly Cabibbo suppressed $D\to \pi a_0(980)$ decays

The singly Cabibbo suppressed (SCS) decays $D\to \pi a_0$, with $a_0\equiv a_0(980)$, have been measured with the branching-fraction ratios $r^{+/-}_{\rm ex}\equiv {\cal B}(D^0\to\pi^- a_0^+)/{\cal B}(D^0\to\pi^+ a_0^-)=7.5^{+2.5}_{-0.8}\pm 1.7$ and $r^{+/0}_{\rm ex}\equiv {\cal B}(D^+\to\pi^0 a_0^+)/{\cal B}(D^+\to\pi^+ a_0^0)=2.6\pm 0.6\pm 0.3$, deviating significantly from the short-distance expectations $(r^{+/-},r^{+/0})\simeq (0.07,0.2)$. This discrepancy indicates the necessity of long-distance rescattering effects. In particular, the process $D\to K^*K\to a_0\pi$ generates ${\cal M}_s$ comparable in magnitude to ${\cal M}_d$ in the amplitude ${\cal M}=\lambda_d{\cal M}_d+\lambda_s{\cal M}_s$, with $\lambda_q\equiv V_{cq}^*V_{uq}$, accompanied by nontrivial strong phases essential for $CP$ violation. Consequently, the direct $CP$ asymmetries naturally arise at the ${\cal O}(10^{-3})$ level, for example, ${\cal A}_{CP}(D^0\to\pi^- a_0^+)=(-0.7\pm 0.1\pm 0.1\pm 0.1)\times 10^{-3}$, ${\cal A}_{CP}(D^+\to\pi^0 a_0^+)=(-1.4\pm 0.1\pm 0.1\pm 0.1)\times 10^{-3}$, and ${\cal A}_{CP}(D^0\to\pi^+ a_0^-)=(-2.1\pm 0.9\pm 1.1\pm 0.4)\times 10^{-3}$. These results establish SCS $D\to \pi a_0$ decays as a new avenue for probing $CP$ violation.

hep-ph↗

arXiv2025

Rescattering-induced $D\to SS$ weak decays

We investigate two-body non-leptonic $D\to SS$ weak decays, where $S$ denotes a light scalar meson such as $a_0/a_0(980)$, $f_0/f_0(980)$, or $\sigma_0/f_0(500)$. Short-distance topologies from $W$-boson emission and annihilation (exchange) are found to be negligible, while long-distance final-state interactions provide the dominant contributions. In particular, triangle rescattering processes, $D \to \pi\eta^{(\prime)} \to \sigma_0 a_0$ and $D \to a_1(1260)\eta \to \sigma_0 a_0$, mediated by pion exchange in $\pi\eta^{(\prime)}$ and $a_1(1260)\eta$ scatterings, respectively, are identified as the leading mechanisms. Our calculations yield branching fractions ${\cal B}(D_s^+ \to \sigma_0 a_0^+) = (1.0 \pm 0.2^{+0.1}_{-0.2}) \times 10^{-2}$, ${\cal B}(D^+ \to \sigma_0 a_0^+) = (1.1 \pm 0.2^{+0.1}_{-0.2}) \times 10^{-3}$, and ${\cal B}(D^0 \to \sigma_0 a_0^0) = (0.9 \pm 0.2^{+0.2}_{-0.3}) \times 10^{-5}$. For the Cabibbo-allowed decay mode $D_s^+ \to f_0 a_0^+$, the near-threshold condition $m_{D_s}\simeq m_{f_0}+m_{a_0}$ limits the phase space, suppressing the branching fraction to $(3.4\pm0.3^{+0.4}_{-0.9})\times 10^{-4}$. These results highlight rescattering-induced $D\to SS$ decays as promising channels for experimental studies at BESIII, Belle(-II), and LHCb.

hep-ph↗

arXiv2025

Probing the elusive $\kappa/K_0^*(700)$ resonance in semileptonic $D$ decays

The $\kappa/K_0^*(700)$ meson remains the most elusive among the light scalar resonances, with its presence in weak decays obscured by limited precision in branching fraction measurements. As a result, the true nature of the $\kappa$ remains difficult to explore. Through a partial-wave analysis of the semileptonic decay $D^+ \to K^-\pi^+ e^+ \nu_e$, we extract ${\cal B}(D^+ \to \bar\kappa^0 e^+ \nu_e, \bar\kappa^0 \to K^-\pi^+) =(2.2 \pm 0.1) \times 10^{-3}$. Previously considered negligible, this contribution is now shown to dominate the observed s-wave branching fraction. This reveals that clear evidence for the $\kappa$ in weak decays has long existed, but was misidentified as part of the non-resonant background. The extracted $D^+ \to \bar\kappa^0$ form factor, $f^+(0) = 0.32 \pm 0.01$, is significantly smaller than the $q\bar q$ prediction of $0.82 \pm 0.05$, and closely aligns with the $q^2\bar q^2$ expectation of $0.36 \pm 0.02$. Notably, this finding supports a compact tetraquark interpretation of the $\kappa$ meson.

hep-ph↗

arXiv2025

Hidden charm ${\cal P}_{cs}(4338)^0$ production in baryonic $B^-\to J/ψΛ\bar p$ decay

We investigate the resonant baryonic $B$ decay $B^-\to {\cal P}_{cs}^0\bar p,{\cal P}_{cs}^0\to J/ψΛ$, where ${\cal P}_{cs}^0\equiv {\cal P}_{cs}(4338)^0$ is identified as a hidden charm pentaquark candidate with strangeness. By interpreting ${\cal P}_{cs}^0$ as the $Ξ_c\bar D$ molecule that strongly decays into $J/ψΛ$ and $η_cΛ$, we discover a dominant triangle rescattering effect for $B^-\to {\cal P}_{cs}^0\bar p$, initiated by $B^-\to J/ψK^-$. Through the exchange of a $\bar Λ$ anti-baryon, $J/ψ$ and $K^-$ undergo rescattering, transforming into ${\cal P}_{cs}^0$ and $\bar p$, respectively. Based on this rescattering mechanism, we calculate ${\cal B}(B^-\to {\cal P}_{cs}^0\bar p,{\cal P}_{cs}^0\to J/ψΛ) =(1.4^{+2.1}_{-1.1})\times10^{-6}$, which is consistent with the measured data.

hep-ph↗

arXiv2024

Charmful two-body $\Omega_b$ decays in the light-front quark model

We investigate the singly and doubly charmful two-body $\Omega_b^-$ decays using the light-front quark model. Our findings reveal that most branching fractions calculated in this study, such as ${\cal B}(\Omega_b^-\to\Xi^- D^0,\Xi^{-}D^{*0})$, can be ten to one hundred times larger than those reported in previous calculations. Additionally, we interpret the ratio ${\cal B}(\Omega_b^-\to\Omega^- J/\psi)/{\cal B}(\Omega_b^-\to\Omega^- \eta_c)\simeq 3.4$ within the helicity framework. While the decay involving external $W$-boson emission appears to be suppressed by the $b\to u \bar c s$ weak transition, it still yields a significant branching fraction. For instance, ${\cal B}(\Omega_b^-\to\Xi^0 D_s^{*-})=(5.9-14.2)\times 10^{-5}$, ${\cal B}(\Omega_b^-\to\Xi^{*0}D_s^{-})=(6.7-12.1)\times10^{-5}$, and ${\cal B}(\Omega_b^-\to\Xi^{*0}D_s^{*-})=(12.8-26.7)\times10^{-5}$, with values reaching as large as $10^{-4}$. These predictions are well within the experimental reach of LHCb.

hep-ph↗

arXiv2020

A diagrammatic analysis of two-body charmed baryon decays with flavor symmetry

We study the two-body anti-triplet charmed baryon decays based on the diagrammatic approach with $SU(3)$ flavor symmetry. We extract the two $W$-exchange effects as $E_{\bf B}$ and $E^\prime$ that contribute to the $Λ_c^+ \to Ξ^0 K^+$ decay, together with the relative phases, where $E_{\bf B}$ gives the main contribution. Besides, we find that ${\cal B}(Λ_c^+\to pπ^0)=(0.8 ^{+0.9}_{-0.8})\times 10^{-4}$, which is within the experimental upper bound. Particularly, we obtain ${\cal B}(Ξ_c^+\toΞ^{0} π^{+})=(9.3 \pm 3.6)\times 10^{-3}$, ${\cal B}(Ξ_c^0\to Ξ^-π^+,Λ^0\bar K^0)=(19.3 \pm 2.8,8.3 \pm 5.0)\times 10^{-2}$ and ${\cal B}(Ξ_c^0\to Ξ^- K^+)=(5.6 \pm 0.8)\times 10^{-4}$, which all agree with the data. For the singly Cabibbo suppressed $Λ_c^+$ decays, we predict that ${\cal B}(Λ_c^+ \to n π^{+},p η^\prime,Σ^{+} K^{0}) =(7.7\pm 2.0,7.1 \pm 1.4,19.1 \pm 4.8)\times 10^{-4}$, which are accessible to the experiments at BESIII, BELLEII and LHCb.

hep-ph↗