arXiv subjects

Yu-Shan Ren

Publications and source records attributed to Yu-Shan Ren.

4 recordsLinked to original sources

arXiv2026

Role of the $\Sigma(1430)(1/2^-)$ in the $J/\psi \to \Lambda \bar{\Lambda} \pi^0$ reaction

We study the $J/\psi \to \bar{\Lambda} \Lambda \pi^0$ reaction, an isospin violating reaction, by looking at the trios of baryon-antibaryon-pseudoscalar meson that conform a singlet of $\text{SU}(3)$ in the $u, d, s$ quarks. These terms conserve isospin; however, once the final-state interactions of meson-baryon and meson-antibaryon are taken into account, isospin is violated due to the different masses of particles within the same isospin multiplets. Since the reaction is tied to the interaction of particles, only resonances that are dynamically generated by these interactions show up in the reaction. In this sense, our approach produces the $\Sigma(1430)(1/2^-)$ state, but not the $\Sigma(1385)(3/2^+)$. Comparing with the BESIII data we observe that, within the limited statistics of the experiment, the data show a structure {around $M_{\pi\Lambda} = 1430$ MeV} that is reproduced by the theory, and no signal is seen for the $\Sigma(1385)(3/2^+)$ as the theory predicts. We call for a future update of the experiment once better statistics become available.

hep-ph↗

arXiv2026

Systematic Study of Coupled-Channel Dynamics in Doubly Heavy Hadronic Molecules

Heavy Quark Spin Symmetry (HQSS) is widely use to predict heavy molecules by extending the effective interactions fitted from low-lying states to heavier sectors. In this work, we systematically investigate the reliability of this approach for higher double heavy tetraquarks by comparing a single-channel effective interaction (Scheme I) with an explicit coupled-channel dynamics framework (Scheme II). The interactions are obtained within one-boson-exchange potential model and fixed by fitting the $T_{cc}^+$ lineshape. Utilizing the complex scaling method and $T$-matrix pole analysis, we extract the possible poles in the $S$-wave $D^{(*)}D^{(*)}$, $\bar{B}^{(*)}\bar{B}^{(*)}$ and $D^{(*)}\bar{B}^{(*)}$ systems with $J^{P}=1^+$. We find that both schemes provide consistent descriptions of the lowest-lying state. This confirms isoscalar-dominated $T_{cc}$ as a predominant $DD^*$ molecule (binding energy $\sim$ 381 keV), and predicts an isoscalar deeply bound $T_{bb}$ state ($40-60$ MeV) and an isovector $T^\prime_{bb}$ resonance in the bottom sector, together with a virtual $T_{bc}$ state. In contrast, significant differences emerge for higher-lying states. The inclusion of explicit coupled-channel dynamics modifies the effective interaction and reshapes the pole structure. The states predicted as bound or resonant in the single-channel framework can be shifted far from the physical region or disappear. These results indicate that while single-channel descriptions are adequate for near-threshold states, an explicit treatment of coupled-channel dynamics is required for reliable predictions of excited doubly heavy tetraquarks.

hep-ph↗

arXiv2024

The $ρ(770,1450)\to ωπ$ contributions for three-body decays $B\to\bar{D}^{(*)} ωπ$

The decays $B\to\bar{D}^{(*)} ωπ$ are very important for the investigation of $ρ$ excitations and the test of factorization hypothesis for $B$ meson decays. The $B^{+}\to \bar{D}^{(*)0}ωπ^+$ and $B^{0}\to D^{(*)-}ωπ^+$ have been measured by different collaborations but without any predictions for their observables on theoretical side. In this work, we study the contributions of $ρ(770,1450)\to ωπ$ for the cascade decays $B^{+}\to \bar{D}^{(*)0} ρ^+ \to \bar{D}^{(*)0}ωπ^+$, $B^{0}\to D^{(*)-} ρ^+ \to D^{(*)-}ωπ^+$ and $B_s^{0}\to D_s^{(*)-} ρ^+ \to D^{(*)-}ωπ^+$. We introduce $ρ(770,1450)\to ωπ$ subprocesses into the distribution amplitudes for $ωπ$ system via the vector form factor $F_{ωπ}(s)$ and then predict the branching fractions for the first time for concerned quasi-two-body decays with $ρ(770,1450)\to ωπ$, as well as the corresponding longitudinal polarization fractions $Γ_L/Γ$ for the cases with the vector $\bar{D}^{*0}$ or $D_{(s)}^{*-}$ in their final states. The branching fractions of these quasi-two-body decays are predicted at the order of $10^{-3}$, which can be detected at the LHCb and Belle-II experiments. The predictions for the decays ${B}^0 \to{D}^{*-} ρ(770)^+\to {D}^{*-} ωπ^+$ and ${B}^0 \to {D}^{*-} ρ(1450)^+\to {D}^{*-} ωπ^+$ agree well with the measurements from Belle Collaboration. In order to avoid the pollution from annihilation Feynman diagrams, we recommend to take the $B_s^0 \to D_s^{*-}ρ(770,1450)^+$ decays, which have only emission diagrams at quark level, to test the factorization hypothesis for $B$ decays.

hep-ph↗

arXiv2023

Investigation on the bottom analogs of the $T_{cc}^{+}$

We investigate the doubly bottom state $T^-_{bb}$ composed of two bottom mesons with $J^P=1^+$. The potentials are obtained using the one-boson exchange model. With the heavy quark flavor symmetry, all the parameters in the model are determined by fitting the experimental data of doubly charmed state $T_{cc}^{+}$ from our previous work. Our analysis indicates that the isospin symmetry is well-preserved. We identify a deeply bound $T^-_{bb}$ state with quantum numbers $I(J^{P})=0(1^+)$, in contrast to the loosely bound $T_{cc}^{+}$. Additionally, we discover a resonant $T^-_{bb}$ state with $I(J^{P})=1(1^+)$. Furthermore, our investigation into the $\bar{B}\bar{B}^*$-$\bar{B}^*\bar{B}^*$ coupled channel effect reveals its important impact. The binding energy of the bound $I(J^{P})=0(1^+)$ states becomes deeper, while the resonant $T^-_{bb}$ state with $I(J^{P})=1(1^+)$ remains nearly unchanged.

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