arXiv subjects

Quanxing Ye

Publications and source records attributed to Quanxing Ye.

4 recordsLinked to original sources

arXiv2026

Does $\psi(4660)$ exist?

We investigate $S$-wave coupled-channel effects in $e^+e^-$ annihilation in the energy region $\sqrt{s}\in[4.0,5.5]\,\mathrm{GeV}$, including the open-charm final states $\Lambda_c^+\bar{\Lambda}_c^-$, $\Xi_c^+\bar{\Xi}_c^-$, $\Xi_c^0\bar{\Xi}_c^0$, and $\psi(2S)\pi^+\pi^-$. Motivated by the recent high-precision BESIII measurements of the $e^+e^-\to\Lambda_c^+\bar{\Lambda}_c^-$ cross section, which shows a nearly flat lineshape around $4.66~\mathrm{GeV}$ and a non-zero value right at threshold, in striking contrast to earlier Belle observation, we construct an effective coupled-channel framework by using short-ranged contact potentials in the heavy-quark limit.Two charmonium states, i.e. the $\psi(4360)$ and $\psi(4660)$, assigned as the $4S$ and $5S$ excitations, respectively, are explicitly included. The scattering amplitudes are obtained by solving the Lippmann-Schwinger equation.The Belle and BESIII $e^+e^-\to\Lambda_c^+\bar{\Lambda}_c^-$ and $e^+e^-\to\psi(2S)\pi^+\pi^-$ cross-sections reveal markedly different pole structures for the $\psi(4360)$. It emerges as a dynamically generated state for the Belle data, whereas it appears as a bare state in the BESIII fit. In contrast, the $\psi(4660)$ pole found on the unphysical Riemann sheet above the $\Lambda_c^+\bar{\Lambda}_c^-$ threshold is associated with a bare pole on the real axis in both fits.

hep-ph↗

arXiv2026

Why is the $Z_c(3900)$ absent in the $h_c\pi$ final state?

In this work, we perform a comprehensive phenomenological analysis of the exotic hadronic states $Z_c(3900)$, $Z_c(4020)$, $Z_b(10610)$ and $Z_b(10650)$ within the framework of Heavy Quark Spin Symmetry (HQSS) and its violation. By constructing S-wave contact interactions between elastic ($D\bar{D}^*/D^*\bar{D}^*$ or $B\bar{B}^*/B^*\bar{B}^*$) and inelastic ($J/\psi\pi, h_c\pi$ or $\Upsilon\pi$, $h_b\pi$) channels, we solve the Lippmann-Schwinger equation to obtain physical production amplitudes and perform a global fit to experimental invariant-mass spectra. Our results demonstrate a striking difference between the charm and bottom sectors: HQSS violation is negligible in the bottom system, leading to comparable peak structures for both $Z_b$ states in all hidden-bottom decay channels. In contrast, significant HQSS breaking is required to describe the $Z_c$ system, where the violation is predominantly concentrated in the elastic interactions. This explains the observed selectivity: $Z_c(3900)$ appears prominently only in $J/\psi\pi$, while $Z_c(4020)$ appears only in $h_c\pi$. Pole analysis confirms the molecular nature of the states, with the $Z_c(4020)$ likely arising from a threshold cusp effect. The model's robustness is verified against variations of the form factor and cutoff, showing stable results.

hep-ph↗

arXiv2025

Resonance parameters of the vector charmoniumlike state $G(3900)$

Motivated by the updated analysis of the $G(3900)$ by the BESIII collaboration, we perform a global analysis of the cross sections of the $e^+e^-\to D\bar{D}$, $e^+e^-\to D\bar{D}^*+c.c.$, $e^+e^-\to D^*\bar{D}^*$ processes, especially focusing on the properties of the $G(3900)$. As the energy region of interest is limited by the next opening threshold, i.e. the $D_1\bar{D}$ threshold, we focus on the energy region $[3.7,4.25]~\mathrm{GeV}$, where three charmonia $ψ(1D)$, $ψ(3S)$ and $ψ(2D)$ explicitly contribute to the cross sections. By constructing the $P$-wave contact interaction between the $(D,D^*)$ doublet and its antiparticle in the heavy quark limit, we extract the physical scattering amplitude by solving the Lippmann-Schwinger equation. No matter whether three or two charmonium states are included in our framework, we always find a dynamically generated state corresponding to the $G(3900)$, which suggests it to be a $P$-wave dynamically generated state. We also predict several dynamically generated states in the corresponding $1^{-+}$ channel. These states can be further searched for in the electron-positron annihilation process involving the emission of a single photon.

hep-ph↗

arXiv2024

Two-body hadronic weak decays of bottomed hadrons

The structure of light diquarks plays a crucial role in the formation of exotic hadrons beyond the conventional quark model, especially in their line shapes of bottomed hadron decays. We study the two-body hadronic weak decays of bottomed baryons and bottomed mesons to probe the light diquark structure and pin down the quark-quark correlations in the diquark picture. We find that the light diquark does not favor a compact structure. For instance, the isoscalar diquark $[ud]$ in $Λ_{b}^{0}$ can be easily split and rearranged to form $Σ_{c}^{(*)}\bar{D}^{(*)}$ via the color-suppressed transition. This provides a hint that the hidden charm pentaquark states produced in $Λ^0_b$ decays could be the $Σ_{c}^{(*)}\bar{D}^{(*)}$ hadronic molecular candidates. This quantitative study resolves the apparent conflicts between the production mechanism and molecular nature of these $P_c$ states observed in experiment.

hep-ph↗