arXiv subjects

Yun-Hua Chen

Publications and source records attributed to Yun-Hua Chen.

At least 19 recordsLinked to original sources

arXiv2026

Determination of the $Z_c(3900)$ and the $Z_{cs}(3985)$ states from joint analysis of experimental and lattice data

We present a unified analysis of the $Z_c(3900)$ and $Z_{cs}(3985)$ states considering both experimental and lattice data. The study simultaneously includes the processes $e^+e^- \rightarrow J/ψπ^+π^-, J/ψK^+ K^-, D^0 D^{\ast-} π^+, (D^{\ast 0} D_s^{-}+D^0 D_s^{\ast -}) K^+$, together with finite-volume energy levels from recent lattice QCD simulations. Open-charm meson loops with triangle singularities, the $J/ψπ(J/ψ\bar{K})$-$\bar{D}D^*(\bar{D}D^*_s)$ coupled-channel interactions, and the $ππ$-$K\bar K$ final-state interaction are all taken into account. We find that pole contributions associated with the $Z_c(3900)$ and $Z_{cs}(3985)$ are indispensable for describing the data. The successful joint description of the experimental and lattice data supports the interpretation that the $Z_c(3900)$ and $Z_{cs}(3985)$ are SU(3) flavor partners within the same octet multiplet and indicates that both are resonance states. The extracted pole masses and half-widths of the $Z_c(3900)$ and the $Z_{cs}(3985)$ are $(3879.6 \pm 4.8)$ MeV and $(32.2 \pm 4.7)$ MeV, and $(3976.9 \pm 5.1)$ MeV and $(28.8 \pm 5.9)$ MeV, respectively. The ratios of the $Z_c(Z_{cs})$ couplings to the $D\bar D^*(D_s\bar{D}^\ast+D\bar{D}_s^\ast)$ and $J/ψπ(J/ψK)$ channels are also determined. A compositeness analysis indicates that, although the $D\bar D^* (D_s\bar{D}^\ast+D\bar{D}_s^\ast)$ component in the $Z_c(3900) (Z_{cs}(3985))$ state is sizable, additional components are still needed to form these exotic states.

hep-ph↗

arXiv2026

Decoding the structure near the $π^+π^-$ mass threshold in $ψ(3686) \rightarrow J/ψπ^+π^-$ decays

In light of recent high-precision data taken by the BESIII Collaboration, we reconsider the dipion transition $ψ(3686) \rightarrow J/ψπ^+π^-$. The strong pion-pion final-state interactions are taken into account model-independently by using dispersion theory. We find that we can reproduce the substructure near the $π^+π^-$ threshold observed experimentally without introducing an extra resonance state. While a helicity-flip amplitude plays an important role for the formation of the dip in the invariant-mass distribution, the virtual exchange of the charmoniumlike exotic $Z_c(3900)$ state improves the fit quality only slightly.

hep-ph↗

arXiv2026

Unified study of $B_s^0 \to X(3872) π^+π^- (K^+ K^-)$ and $B_s^0 \to ψ(2S) π^+π^- (K^+ K^-)$ processes

We perform a unified description of the experimental data of the $π^+π^-$ invariant mass spectra of $B_s^0 \to ψ(2S) π^+π^-$, the $π^+π^-$ and $K^+ K^-$ invariant mass spectra of $B_s^0 \to X(3872) π^+π^- (K^+ K^-)$, and the ratio of branch fractions $\mathcal{B}[B_s^0 \to X(3872)(K^+K^-)_{{\rm non-}ϕ}]/ \mathcal{B}[B_s^0 \to X(3872)π^+ π^-)$. The strong final state interactions between the two pseudoscalars are taken into account using a parametrization fulfilling unitarity and analyticity. We find that there is universality in the coupling constants for $B_s^0 \to ψ(2S) π^+π^-$ and $B_s^0 \to J/ψπ^+π^-$ processes. While the couplings of $B_s^0 \to X(3872) π^+π^-$ are about half of magnitude smaller than the couplings of $B_s^0 \to ψ(2S) π^+π^-$, which indicates that the $X(3872)$ is different from a pure charmonium state. Furthermore, we find that the $f_0(1500)$ plays an important role in the $B_s^0 \to ψ(2S) π^+π^-$ and the $B_s^0 \to X(3872) π^+π^- (K^+ K^-)$ processes, though the phase space of $B_s^0 \to X(3872) f_0(1500)$ is small. Also we predict the ratio of branch fractions $\mathcal{B}[B_s^0 \to ψ(2S)(K^+K^-)_{{\rm non-}ϕ}]/ \mathcal{B}[B_s^0 \to ψ(2S)π^+ π^-]$ and the $K^+ K^-$ invariant mass distribution of $B_s^0 \to ψ(2S)K^+K^-$.

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arXiv2025

Chromopolarizability of charm-beauty quarkonium from $B_c(2S) \rightarrow B_cππ$ transition

The chromopolarizability of a charm-beauty quarkonium characterizes its interaction with soft gluonic fields and can be probed through heavy quarkonium decays. Using the dispersion theory which considers the $ππ$ final state interaction model-independently, we analyze the transition $B_c(2S) \rightarrow B_cπ^+π^-$ and determine the chromopolarizability $α_{B_c(2S) B_c}=(0.66\pm 0.25)$ GeV$^{-3}$ and the parameter $κ=-0.02\pm 0.13$. Our results indicate that the transitional chromopolarizability of the $c\bar{b}$ state lies between the transitional chromopolarizabilities of the $c\bar{c}$ and $b\bar{b}$ states. These findings provide valuable insights into the interactions of charm-beauty quarkonium with light hadrons.

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arXiv2024

Precise determination of the pole position of the exotic $Z_c(3900)$

We perform a unified description of the experimental data of the $π^+π^-$ and $J/ψπ^\pm$ invariant mass spectra for $e^+e^- \rightarrow J/ψπ^+π^-$ and the $D^0 D^{\ast-}$ mass spectrum for $e^+e^- \rightarrow D^0 D^{\ast-} π^+$ at $e^+e^-$ center-of-mass energies 4.23 and 4.26 GeV. The analysis takes into account open-charm meson loops that contain triangle singularities, the $J/ψπ$-$D\bar D^*$ coupled-channel interaction respecting unitarity, and the strong $ππ$-$K\bar K$ final state interaction using dispersion relations. The analysis leads to a precise determination of the $Z_c(3900)$ pole with the pole mass and width $(3880.7 \pm 1.7_\text{stat}\pm 22.4_\text{syst})$ MeV and $(35.9 \pm 1.4_\text{stat}\pm 15.3_\text{syst})$ MeV, respectively, and hints at that the $D\bar D^*$ molecular and non-molecular components are of similar importance in the $Z_c(3900)$ formation.

hep-ph↗

arXiv2023

Momentum-dependence of $ρ-ω$ mixing in the pion vector form factor and its effect on $(g-2)_μ$

The inclusion of the $ρ-ω$ mixing effect is essential for a precise description of the pion electromagnetic form factor in the $e^+e^- \rightarrow π^+π^-$ process, which quantifies the two-pion contribution to the anomalous magnetic moment of the muon $a_μ$. In this paper, we analyse the momentum dependence of the $ρ-ω$ mixing by considering loop contributions at the next-to-leading order in the $1/N_C$ expansion within the framework of resonance chiral theory. We revisit the work [Y. H. Chen, D. L. Yao, and H. Q. Zheng, Commun. Theor. Phys. 69 (2018) 1], considering the contribution arising from the kaon mass splitting in the kaon loops and the latest experimental data. We perform two kinds of fits (with momentum-independent or momentum-dependent $ρ-ω$ mixing amplitude) to describe the $e^+e^-\rightarrow π^+π^-$ and $τ\rightarrow ν_τ2π$ data within the energy region of 600$\sim$900 MeV and the decay width of $ω\rightarrow π^+π^-$, and compare their results. Our findings indicate that both the momentum-independent and momentum-dependent $ρ-ω$ mixing schemes provide appropriate descriptions of the data. However, the momentum-dependent scheme exhibits greater self-consistency, considering the reasonable imaginary part of the mixing matrix element $Π_{ρω}$ obtained. Regarding the contribution to the anomalous magnetic moment of the muon, $a_μ^{ππ}|_{[0.6,0.9]\text{GeV}}$, the results obtained from the fits considering the momentum-dependent $ρ-ω$ mixing amplitude agree well with those obtained without incorporating the momentum dependence of the $ρ-ω$ mixing, within the margin of errors. Furthermore, based on the fitted values of the relevant parameters, we observe that the decay width of $ω\rightarrow π^+π^-$ is predominantly influenced by the $ρ-ω$ mixing effect.

hep-ph↗

arXiv2023

$ϕ(2170)$ decaying to $ϕππ$ and $ϕK\bar{K}$

Within the framework of dispersion theory, we study the the processes $e^+e^-\to ϕ(2170) \to ϕππ(K\bar{K})$. The strong pion-pion final-state interactions, especially the $K\bar{K}$ coupled channel in the $S$-wave, are taken into account in a model-independent way using the Omnès function solution. Through fitting the experimental data of the $ππ$ and $ϕπ$ invariant mass distributions of the $e^+e^- \to ϕ(2170) \to ϕπ^+π^-$ process, the low-energy constants in the chiral Lagrangian are determined. The theoretical prediction for the cross sections ratio ${σ(e^+e^- \to ϕ(2170)\to ϕK^+ K^-)}/{σ(e^+e^- \to ϕ(2170)\to ϕπ^+π^-)}$ is given, which could be useful for selecting the physical solution when the fit to the $e^+e^- \to ϕK^+ K^-$ cross section distribution is available in the future. Our results suggest that above the kinematical threshold of $ϕK\bar{K}$, the mechanism $e^+e^- \to ϕK^+ K^-$ with the kaons rescattering to a pion pair plays an important role in the $e^+e^- \to ϕπ^+π^-$ transition.

hep-ph↗

arXiv2023

Effective-Lagrangian study of $ψ'(J/ψ) \to VP$ and the insights into $ρπ$ puzzle

Within the effective Lagrangian approach, we carry out a unified study of the $J/ψ(ψ')\to VP$, $J/ψ\to Pγ$ and relevant radiative decays of light-flavor hadrons. Large amount of experimental data, including the various decay widths and electromagnetic form factors, are fitted to constrain the numerous hadron couplings. Relative strengths between the strong and electromagnetic interactions are revealed in the $J/ψ\to VP$ and $ψ' \to VP$ processes. The effect from the strong interaction is found to dominate in the $J/ψ\to ρπ$ decay, while the electromagnetic interaction turns out to be the dominant effect in $ψ' \to ρπ$ decay, which provides an explanation to the $ρπ$ puzzle. For the $J/ψ\to K^{*}\bar{K}+\bar{K}^{*}K$ and $ψ' \to K^{*}\bar{K}+\bar{K}^{*}K$, the former process is dominated by the strong interactions, and the effects from the electromagnetic parts are found to be comparable with those of strong interactions in the latter process. Different $SU(3)$ breaking effects from the electromagnetic parts appear in the charged and neutral channels for the $ψ' \to K^{*}\bar{K}+\bar{K}^{*}K$ processes explain the rather different ratios between $B(ψ'\to K^{*+}K^{-}+K^{*-}K^{+})/B(J/ψ\to K^{*+}K^{-}+K^{*-}K^{+})$ and $B(ψ'\to K^{*0}\bar{K}^{0}+\bar{K}^{*0}K^{0})/B(J/ψ\to K^{*0}\bar{K}^{0}+\bar{K}^{*0}K^{0})$.

hep-ph↗

arXiv2021

Study of the $Y(4660)$ from a light-quark perspective

In this paper, we try to reveal the structure of the $Y(4660)$ from the light-quark perspective. We study the dipion invariant mass spectrum and the helicity angular distributions of the $e^+ e^- \to Y(4660) \to ψ(2S) π^+π^-$ process. In particular, we consider the effects of different light-quark SU(3) eigenstates inside the $Y(4660)$. The strong pion-pion final-state interactions as well as the $K\bar{K}$ coupled channel in the $S$-wave are taken into account model independently by using dispersion theory. We find that the light-quark SU(3) octet state plays a significant role in this transition, implying that the $Y(4660)$ contains a large light-quark component and thus might not be a pure conventional charmonium state. In the fit scheme considering both the SU(3) singlet and SU(3) octet states, two solutions are found, and both solutions reproduce the $ππ$ invariant mass spectra well. New measurement data with higher statistics in the future will be helpful to better distinguish these two solutions.

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arXiv2019

Light-quark components analysis and the nature of the $Y(4260)$

We study the processes $e^+ e^- \to Y(4260) \to J/ψππ(K\bar{K})$. The strong final-state interactions, especially the coupled-channel ($ππ$ and $K\bar{K}$) final-state interaction in the $S$-wave are taken into account in a model-independent way using dispersion theory. It is found that the light-quark SU(3) octet state plays a significant role in these transitions, implying that the $Y(4260)$ contains a large light-quark component. Our findings suggest that the $Y(4260)$ is neither a hybrid nor a conventional charmonium state. Furthermore, through an analysis of the ratio of the light-quark SU(3) octet and singlet components, we show that the $Y(4260)$ does not behave like a pure $\bar D D_1$ hadronic molecule as well.

hep-ph↗

arXiv2019

Predictions of $Υ(4S) \to h_b(1P,2P) π^+π^-$ transitions

In this work, we study the contributions of the intermediate bottomoniumlike $Z_b$ states and the bottom meson loops in the heavy quark spin flip transitions $Υ(4S) \to h_b(1P,2P) π^+π^-$. Depending on the constructive or destructive interferences between the $Z_b$-exchange and the bottom meson loops mechanisms, we predict two possible branching ratios for each process: BR$_{Υ(4S) \to h_b(1P)π^+π^-}\simeq\big(1.2^{+0.8}_{-0.4}\times10^{-6}\big)$ or $\big( 0.5^{+0.5}_{-0.2}\times10^{-6}\big)$, and BR$_{Υ(4S) \to h_b(2P)π^+π^-}\simeq \big(7.1^{+1.7}_{-1.1}\times10^{-10}\big)$ or $\big( 2.4^{+0.2}_{-0.1}\times10^{-10}\big)$. The bottom meson loops contribution is found to be much larger than the $Z_b$-exchange contribution in the $Υ(4S) \to h_b(1P) ππ$ transitions, while it can not produce decay rates comparable to the heavy quark spin conserved $Υ(4S) \to Υ(1S,2S) ππ$ processes. We also predict the branch fractions of $ψ(3S,4S) \to h_c(1P)π^+π^-$ contributed from the charm meson loops.

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arXiv2019

Chromopolarizabilities of bottomonia from the $Υ(2S,3S,4S) \to Υ(1S,2S)ππ$ transitions

The dipion transitions $Υ(2S,3S,4S) \to Υ(1S,2S)ππ$ are systematically studied by considering the mechanisms of the hadronization of soft gluons, exchanging the bottomoniumlike $Z_b$ states, and the bottom-meson loops. The strong pion-pion final-state interaction, especially including the channel coupling to $K\bar{K}$ in the $S$-wave, is taken into account in a model-independent way using the dispersion theory. Through fitting to the available experimental data, we extract values of the transition chromopolarizabilities $|α_{Υ(mS)Υ(nS)}|$, which measure the chromoelectric couplings of the bottomonia with soft gluons. It is found that the $Z_b$ exchange has a slight impact on the extracted chromopolarizablity values, and the obtained $|α_{Υ(2S)Υ(1S)}|$ considering the $Z_b$ exchange is $(0.29\pm 0.20)~\text{GeV}^{-3}$. Our results could be useful in studying the interactions of bottomonium with light hadrons.

hep-ph↗

arXiv2019

Chromopolarizability of charmonium and $ππ$ final state interaction revisited

The chromopolarizability of a quarknonium describes the quarknonium's interaction with soft gluonic fields and can be measured in the heavy quarkonium decays. Within the framework of dispersion theory which consider the $ππ$ final state interaction (FSI) model-independently, we analyze the transition $ψ^\prime\to J/ψπ^+π^-$ and obtain the chromopolarizability $α_{ψ^\prime ψ}$ and the parameter $κ$. It is found that the $ππ$ FSI plays an important role in extracting the chromopolarizability from the experimental data. The obtained chromopolarizability with the FSI is reduced to about 1/2 of that without the FSI. With the FSI, we determine the chromopolarizability $|α_{ψ^\primeψ}|=(1.44\pm 0.02)$ GeV$^{-3}$ and the parameter $κ=0.139\pm 0.005.$ Our results could be useful in studying the interactions of charmonium with light hadrons.

hep-ph↗

arXiv2019

Nature of the $Y(4260)$: A light-quark perspective

The $Y(4260)$ has been one of the most puzzling pieces among the so-called $XYZ$ states. In this paper, we try to gain insights into the structure of the $Y(4260)$ from the light-quark perspective. We study the dipion invariant mass spectrum of the $e^+ e^- \to Y(4260) \to J/ψπ^+π^-$ process and the ratio of the cross sections ${σ(e^+e^- \to J/ψK^+ K^-)}/{σ(e^+e^- \to J/ψπ^+π^-)}$. In particular, we consider the effects of different light-quark SU(3) eigenstates inside the $Y(4260)$. The strong pion-pion final-state interactions as well as the $K\bar{K}$ coupled channel in the $S$-wave are taken into account in a model-independent way using dispersion theory. We find that the SU(3) octet state plays a significant role in these transitions, implying that the $Y(4260)$ contains a large light-quark component. Our findings suggest that the $Y(4260)$ is neither a hybrid nor a conventional charmonium state, and they are consistent with the $Y(4260)$ having a sizeable $\bar D D_1$ component which, however, is not completely dominant.

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arXiv2018

The China Jinping Underground Laboratory and its Early Science

The China Jinping Underground Laboratory, inaugurated in 2010, is an underground research facility with the deepest rock overburden and largest space by volume in the world. The first-generation science programs include dark matter searches conducted by the CDEX and PandaX experiments. These activities are complemented by measurements of ambient radioactivity and installation of low-background counting systems. Phase II of the facility is being constructed, and its potential research projects are being formulated. In this review, we discuss the history, key features, results, and status of this facility and its experimental programs, as well as their future evolution and plans.

hep-ex↗

arXiv2017

A study of $ρ-ω$ mixing in resonance chiral theory

The strong and electromagnetic corrections to $ρ-ω$ mixing are calculated using a SU(2) version of resonance chiral theory up to next-to-leading orders in $1/N_C$ expansion, respectively. Up to our accuracy, the effect of the momentum dependence of $ρ-ω$ mixing is incorporated due to the inclusion of loop contributions. We analyze the impact of $ρ-ω$ mixing on the pion vector form factor by performing numerical fit to the data extracted from $e^+e^-\rightarrow π^+π^-$ and $τ\rightarrow ν_τ2π$, while the decay width of $ω\rightarrow π^+π^-$ is taken into account as a constraint. It is found that the momentum dependence is significant in a good description of the experimental data. In addition, based on the fitted values of the involved parameters, we analyze the decay width of $ω\rightarrow π^+π^-$, which turns out to be highly dominated by the $ρ-ω$ mixing effect.

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arXiv2017

Effects of $Z_b$ states and bottom meson loops on $Υ(4S) \to Υ(1S,2S) π^+π^-$ transitions

We study the dipion transitions $Υ(4S) \rightarrow Υ(nS) π^+π^-$ $(n=1,2)$. In particular, we consider the effects of the two intermediate bottomoniumlike exotic states $Z_b(10610)$ and $Z_b(10650)$ as well as bottom meson loops. The strong pion-pion final-state interactions, especially including channel coupling to $K\bar{K}$ in the $S$-wave, are taken into account model-independently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the $Z_b$-exchange terms. For the $Υ(4S) \rightarrow Υ(2S) π^+π^-$ decay, the result shows that including the effects of the $Z_b$-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the $ππ$ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the $Υ(4S) \rightarrow Υ(1S) π^+π^-$ decay, we show that there is a narrow dip around 1 GeV in the $ππ$ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower $Υ$ states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the $Υ(4S) \rightarrow Υ(1S) K^+ K^-$ process.

hep-ph↗

arXiv2016

Effect of $Z_b$ states on $Υ(3S)\toΥ(1S)ππ$ decays

Within the framework of dispersion theory, we analyze the dipion transitions between the lightest $Υ$ states, $Υ(nS) \rightarrow Υ(mS) ππ$ with $m < n \leq 3$. In particular, we consider the possible effects of two intermediate bottomoniumlike exotic states $Z_b(10610)$ and $Z_b(10650)$. The $ππ$ rescattering effects are taken into account in a model-independent way using dispersion theory. We confirm that matching the dispersive representation to the leading chiral amplitude alone cannot reproduce the peculiar two-peak $ππ$ mass spectrum of the decay $Υ(3S) \rightarrow Υ(1S) ππ$. The existence of the bottomoniumlike $Z_b$ states can naturally explain this anomaly. We also point out the necessity of a proper extraction of the coupling strengths for the $Z_b$ states to $Υ(nS)π$, which is only possible if a Flatté-like parametrization is used in the data analysis for the $Z_b$ states.

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