arXiv subjects

Chao Chen

Publications and source records attributed to Chao Chen.

At least 361 records · Page 20Linked to original sources

arXiv2025

Observation of the charmonium decay $η_c\toγγ$ in $J/ψ\toγη_c$

Using $(2712.4\pm14.3)\times10^{6}$ $ψ(3686)$ events collected with the BESIII detector at the BEPCII collider, the decay $η_c\toγγ$ in $J/ψ\toγη_c$ is observed. We determine the product branching fraction $\mathcal{B}(J/ψ\toγη_c)\times\mathcal{B}(η_c\toγγ)=(5.23\pm0.26_{\rm{stat.}}\pm0.30_{\rm{syst.}})\times10^{-6}$. This result is consistent with the LQCD calculation $(5.34\pm0.16)\times10^{-6}$ from HPQCD in 2023. By using the world-average values of $\mathcal{B}(J/ψ\toγη_c)$ and the total decay width of $η_c$, the partial decay width $Γ(η_c\toγγ)$ is determined to be $(11.30\pm0.56_{\rm{stat.}}\pm0.66_{\rm{syst.}}\pm1.14_{\rm{ref.}})~\rm{keV}$, which deviates from the corresponding world-average value by $3.4σ$.

hep-ex↗

arXiv2025

Evidence of doubly OZI-suppressed decay $η_{c} \to ωϕ$ in the radiative decay $J/ψ\to γη_{c}$

Using a sample of $(10087\pm44) \times 10^{6}$ $J/ψ$ events collected with the BESIII detector at the BEPCII collider, the first evidence for the doubly OZI-suppressed decay $η_{c} \to ωϕ$ is reported with a significance of 4.0$σ$. The branching fraction of $η_{c} \to ωϕ$ is measured to be $\mathcal{B}(η_{c} \to ωϕ) = (3.86 \pm 0.92 \pm 0.62) \times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. This result provides valuable insights into the underlying mechanisms of charmonium decays, particularly for processes such as $η_{c} \to VV$ (where $V$ represents a vector meson).

hep-ex↗

arXiv2025

The Mini-SiTian Array: Optical design

Time-domain astronomy is one of the most important areas. Large sky area, deep-field, and short timescale are the priority of time-domain observations. SiTian is an ambitious ground-based project processing all sky optical monitoring, aiming for sky-survey timescale of less than 1 day. It is developed by the Chinese Academy of Sciences, an integrated network of dozens of 1-m-class telescopes deployed worldwide. The Mini-SiTian Telescope Array is carried out for demonstrations on optical design, group scheduling, and software pipeline developments, to overcome the high technical and financial difficulties of SiTian project. One array contains three 300 mm F/3 telescope, with FOV of 5 degrees over 400-1000 nm wavelength range. The Mini-SiTian Telescope Array is now under commissioning in Xinglong Observatory, and a perfect platform for technical research and educational purposes.

astro-ph.IM↗

arXiv2025

TopoCellGen: Generating Histopathology Cell Topology with a Diffusion Model

Accurately modeling multi-class cell topology is crucial in digital pathology, as it provides critical insights into tissue structure and pathology. The synthetic generation of cell topology enables realistic simulations of complex tissue environments, enhances downstream tasks by augmenting training data, aligns more closely with pathologists' domain knowledge, and offers new opportunities for controlling and generalizing the tumor microenvironment. In this paper, we propose a novel approach that integrates topological constraints into a diffusion model to improve the generation of realistic, contextually accurate cell topologies. Our method refines the simulation of cell distributions and interactions, increasing the precision and interpretability of results in downstream tasks such as cell detection and classification. To assess the topological fidelity of generated layouts, we introduce a new metric, Topological Frechet Distance (TopoFD), which overcomes the limitations of traditional metrics like FID in evaluating topological structure. Experimental results demonstrate the effectiveness of our approach in generating multi-class cell layouts that capture intricate topological relationships. Code is available at https://github.com/Melon-Xu/TopoCellGen.

eess.IV↗

arXiv2025

Measurement of the branching fractions of doubly Cabibbo-suppressed $D$ decays

By analyzing $e^+e^-$ collision data collected at the center-of-mass energy of 3.773~GeV with the BESIII detector, corresponding to an integrated luminosity of 20.3~fb$^{-1}$, we measure the branching fractions of the doubly Cabibbo-suppressed (DCS) decays $D^0\to K^+π^-$, $D^0\to K^+π^-π^-π^+$, $D^0\to K^+π^-π^0$, $D^0\to K^+π^-π^0π^0$, $D^+\to K^+π^+π^-$, and $D^+\to K^+K^+K^-$. We also perform the first searches for $D^0\to K^+π^-η$, $D^0\to K^+π^-π^0η$, $D^+\to K^+π^+π^-η$, $D^{+} \to K^{+} \left(π^{+} π^{-} η\right)_{{\rm non}-η^{\prime}}$, and $D^+\to K^+ηη$ and report the first observations and evidence for some of these final states. Combining the measurements with the world averages of the corresponding Cabibbo-favored (CF) decays, the ratios of the DCS/CF branching fractions are obtained. For the $D^{+} \to K^{+} \left(π^{+} π^{-} η\right)_{{\rm non}-η^{\prime}}$ decay, the ratio is significantly larger than the corresponding ratios of the other DCS decays.

hep-ex↗

arXiv2025

Cross section measurement of $e^+e^-\to ηψ(2S)$ and search for $e^+e^-\toη\tilde{X}(3872)$

The energy-dependent cross section for $e^+e^-\to ηψ(2S)$ is measured at eighteen center of mass energies from 4.288 GeV to 4.951 GeV using the BESIII detector. Using the same data samples, we also perform the first search for the reaction $e^+e^-\toη\tilde{X}(3872)$, but no evidence is found for the $\tilde{X}(3872)$ in the $π^+π^- J/ψ$ mass distribution. At each of the eighteen center of mass energies, upper limits at the 90\% confidence level on the cross section for $e^+e^-\toηψ(2S)$ and on the product of the $e^+e^-\toη\tilde{X}(3872)$ cross section with the branching fraction of $\tilde{X}(3872)\toπ^+π^- J/ψ$ are reported.

hep-ex↗

arXiv2025

Observation of the decay $ψ(3686)\rightarrow Σ^{0}\barΣ^{0}ω$

Using a dataset of $(27.12\pm 0.14)\times 10^{8}$ $ψ(3686)$ events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of the decay $ψ(3686)\toΣ^{0}\barΣ^{0}ω$ with a statistical significance of 8.9$σ$. The measured branching fraction is $(1.24 \pm 0.16_{\textrm{stat}} \pm 0.11_{\textrm{sys}}) \times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. Additionally, we investigate potential intermediate states in the invariant mass distributions of $Σ^{0}ω$, $\barΣ^{0}ω$ and $Σ^{0}\barΣ^{0}$. A hint of a resonance is observed in the invariant mass distribution of $M_{Σ^{0}(\barΣ^{0})ω}$, located around 2.06 GeV/$c^2$, with a significance of 2.5$σ$.

hep-ex↗

arXiv2025

TopoDiffusionNet: A Topology-aware Diffusion Model

Diffusion models excel at creating visually impressive images but often struggle to generate images with a specified topology. The Betti number, which represents the number of structures in an image, is a fundamental measure in topology. Yet, diffusion models fail to satisfy even this basic constraint. This limitation restricts their utility in applications requiring exact control, like robotics and environmental modeling. To address this, we propose TopoDiffusionNet (TDN), a novel approach that enforces diffusion models to maintain the desired topology. We leverage tools from topological data analysis, particularly persistent homology, to extract the topological structures within an image. We then design a topology-based objective function to guide the denoising process, preserving intended structures while suppressing noisy ones. Our experiments across four datasets demonstrate significant improvements in topological accuracy. TDN is the first to integrate topology with diffusion models, opening new avenues of research in this area. Code available at https://github.com/Saumya-Gupta-26/TopoDiffusionNet

cs.CV↗

arXiv2025

Stringent test of $CP$ symmetry in $Σ^+$ hyperon decays

The non-leptonic two-body weak decays $Σ^{+} \to p π^{0}$ and $\barΣ^{-} \to \bar{p} π^{0}$ are investigated, utilizing $(1.0087\pm0.0044)\times10^{10}$ $J/ψ$ events and $(2.7124\pm0.0143)\times10^{9}$ $ψ(3686)$ events collected by BESIII experiment. The precision of the weak-decay parameters for the decays $Σ^{+} \to p π^{0}$ ($α_{0}$) and $\barΣ^{-} \to \bar{p} π^{0}$ ($\barα_{0}$) is improved by a factor of three compared to the previous world average. Furthermore, the quantum-entangled $Σ^{+}\barΣ^{-}$ system enables the most precise test of $CP$ symmetry for the decay $Σ^+\to pπ^0$, through the asymmetry observable $A_{CP}=(α_{0}+\barα_{0})/(α_{0}-\barα_{0})$ that is measured to be $-0.0118\pm0.0083_{\rm stat}\pm0.0028_{\rm syst}$. Assuming $CP$ conservation, the average decay parameter is determined to be ${\left< α_{\rm 0}\right>} = (α_0-\barα_0)/2=-0.9869\pm0.0011_{\rm stat}\pm0.0016_{\rm syst}$, which is the most precise measurement of the asymmetry decay parameters in baryon sectors. The angular dependence of the ratio of the polarization of the $Σ^+$ in both $J/ψ$ and $ψ(3686)$ decays is studied for the first time.

hep-ex↗

arXiv2025

Observation of $D^+\toη^\primeμ^+ν_μ$ and First Study of $D^+\to η^\prime \ell^+ν_\ell$ Decay Dynamics

Using $20.3\,\rm fb^{-1}$ of $e^+e^-$ collision data collected at the center-of-mass energy 3.773\,GeV with the BESIII detector, we report the first observation of the semileptonic decay $D^+\to η^\prime μ^+ν_μ$ with significance of $8.6σ$ including systematic uncertainties, and an improved measurement of $D^+\to η^\prime e^+ν_e$. The branching fractions of $D^+\to η^\prime μ^+ν_μ$ and $D^+\to η^\prime e^+ν_e$ are determined to be $(1.92\pm0.28_{\rm stat}\pm 0.08_{\rm syst})\times 10^{-4}$ and $(1.79\pm0.19_{\rm stat}\pm 0.07_{\rm syst})\times 10^{-4}$, respectively. The ratio of the two branching fractions is determined to be ${\mathcal R}_{μ/e}=1.07\pm0.19_{\rm stat}\pm 0.03_{\rm syst}$, which agrees with the theoretical expectation of lepton flavor universality within the Standard Model.From an analysis of the $D^+\to η^\prime \ell^+ν_\ell$ decay dynamics, the product of the hadronic form factor $f_+^{η^{\prime}}(0)$ and the CKM matrix element $|V_{cd}|$ is measured for the first time, giving $f^{η^\prime}_+(0)|V_{cd}| = (5.92\pm0.56_{\rm stat}\pm0.13_{\rm syst})\times 10^{-2}$. The $η-η^\prime$ mixing angle in the quark flavor basis is determined to be $ϕ_{\rm P} =(39.8\pm0.8_{\rm stat}\pm0.3_{\rm syst})^\circ$.

hep-ex↗

arXiv2025

MERGE: Multi-faceted Hierarchical Graph-based GNN for Gene Expression Prediction from Whole Slide Histopathology Images

Recent advances in Spatial Transcriptomics (ST) pair histology images with spatially resolved gene expression profiles, enabling predictions of gene expression across different tissue locations based on image patches. This opens up new possibilities for enhancing whole slide image (WSI) prediction tasks with localized gene expression. However, existing methods fail to fully leverage the interactions between different tissue locations, which are crucial for accurate joint prediction. To address this, we introduce MERGE (Multi-faceted hiErarchical gRaph for Gene Expressions), which combines a multi-faceted hierarchical graph construction strategy with graph neural networks (GNN) to improve gene expression predictions from WSIs. By clustering tissue image patches based on both spatial and morphological features, and incorporating intra- and inter-cluster edges, our approach fosters interactions between distant tissue locations during GNN learning. As an additional contribution, we evaluate different data smoothing techniques that are necessary to mitigate artifacts in ST data, often caused by technical imperfections. We advocate for adopting gene-aware smoothing methods that are more biologically justified. Experimental results on gene expression prediction show that our GNN method outperforms state-of-the-art techniques across multiple metrics.

cs.CV↗

arXiv2025

Measurement of Born cross section of $e^+e^-\toΣ^0\barΣ^0$ at $\sqrt{s} = 3.50-4.95$ GeV

Using $e^+e^-$ collision data collected with the BESIII detector at the BEPCII collider at thirty-two center-of-mass energies from 3.50 to 4.95 GeV, corresponding to an integrated luminosity of 25 $\rm{fb^{-1}}$, we measure the Born cross section of the $e^+e^-\toΣ^0\barΣ^0$ reaction and the effective form factor. No significant charmonium(-like) state, i.e., $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $ψ(4230)$, $ψ(4360)$, $ψ(4415)$, or $ψ(4660)$, decaying into the $Σ^0\barΣ^0$ final state is observed by fitting the $e^+e^- \to Σ^0\barΣ^0$ dressed cross section. The upper limits for the product of the branching fraction and the electronic partial width at the 90% confidence level are provided for each assumed charmonium(-like) state. In addition, the ratios of the Born cross section and the effective form factor between the $e^+e^-\toΣ^0\barΣ^0$ and the $e^+e^-\toΣ^+\barΣ^-$ reactions are provided, which can be used to validate the prediction of the vector meson dominance model.

hep-ex↗

arXiv2025

Search for a $1^{-+}$ molecular state via $e^{+}e^{-} \to γD^{+}_{s} D_{s1}^{-}(2536) +c.c.$

We search, for the first time, for an exotic molecular state with quantum numbers $J^{PC}=1^{-+}$, called $X$, via the process $e^{+}e^{-} \to γD^{+}_{s} D_{s1}^{-}(2536) +c.c.$ using data samples corresponding to a luminosity of $5.8~\mathrm{fb^{-1}}$ across center-of-mass energies from 4.612 to 4.951~GeV, collected with the BESIII detector operating at the BEPCII collider. No statistically significant signal is observed. The upper limits on the product of cross-section and branching fraction $σ({e^{+}e^{-} \to γX}) \times \mathcal{B}(X \to D^{+}_{s} D_{s1}^{-}(2536) +c.c.)$ at 90\% confidence level are reported for each energy point, assuming the $X$ mass to be 4.503~GeV/$c^{2}$ and the width 25, 50, 75, and 100~MeV, respectively.

hep-ex↗

arXiv2025

Measurement of Branching Fractions for $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ and $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$

Based on 4.5 fb$^{-1}$ of $e^{+}e^{-}$ collision data accumulated at center-of-mass energies between $4.600\,\mathrm{GeV}$ and $4.699\,\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fraction of the Cabibbo-favored decay $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ with the precision improved by a factor of 2.8 and report the first evidence for the singly-Cabibbo-suppressed decay $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$. The branching fractions for $Λ_{c}^{+} \rightarrow n K_{S}^{0} π^{+}$ and $Λ_{c}^{+} \rightarrow n K_{S}^{0} K^{+}$ are determined to be $(1.86\pm0.08\pm0.04)\times10^{-2}$ and $\left(3.9^{+1.7}_{-1.4}\pm0.3\right)\times10^{-4}$, respectively, where the first uncertainties are statistical and the second ones are systematic.

hep-ex↗

arXiv2025

Measurement of the branching fractions of $D^+ \to K^+K^-π^+π^+π^-$, $ϕπ^+π^+π^-$, $K^0_SK^+π^+π^-π^0$, $K^0_SK^+η$, and $K^0_SK^+ω$ decays

Using $20.3~\mathrm{fb}^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector operating at the BEPCII collider, the branching fractions of three hadronic charm meson decays, $D^+\to ϕπ^+π^+π^-$, $D^+\to K^0_SK^+π^+π^-π^0$, and $D^+\to K^0_SK^+ω$, are measured for the first time to be $(0.54\pm0.19\pm0.02)\times 10^{-4}$, $(2.51\pm0.34\pm0.14)\times 10^{-4}$, and $(2.02\pm0.35\pm0.10)\times 10^{-4}$, respectively. Futhermore, the branching fractions of $D^+\to K^+K^-π^+π^+π^-$ and $D^+\to K^0_SK^+η$ are measured with improved precision, yielding values of $(0.66\pm0.11\pm0.03)\times 10^{-4}$ and $(2.27\pm0.22\pm0.05)\times 10^{-4}$, respectively.

hep-ex↗

arXiv2025

Wasserstein-regularized Conformal Prediction under General Distribution Shift

Conformal prediction yields a prediction set with guaranteed $1-α$ coverage of the true target under the i.i.d. assumption, which may not hold and lead to a gap between $1-α$ and the actual coverage. Prior studies bound the gap using total variation distance, which cannot identify the gap changes under distribution shift at a given $α$. Besides, existing methods are mostly limited to covariate shift,while general joint distribution shifts are more common in practice but less researched.In response, we first propose a Wasserstein distance-based upper bound of the coverage gap and analyze the bound using probability measure pushforwards between the shifted joint data and conformal score distributions, enabling a separation of the effect of covariate and concept shifts over the coverage gap. We exploit the separation to design an algorithm based on importance weighting and regularized representation learning (WR-CP) to reduce the Wasserstein bound with a finite-sample error bound.WR-CP achieves a controllable balance between conformal prediction accuracy and efficiency. Experiments on six datasets prove that WR-CP can reduce coverage gaps to $3.2\%$ across different confidence levels and outputs prediction sets 37$\%$ smaller than the worst-case approach on average.

cs.LG↗

arXiv2025

Measurement of cross sections of $e^+e^-\to K^0_S K^0_S ψ(3686)$ from $\sqrt{s}=$ 4.682 to 4.951 GeV

The process $e^+e^-\to K^0_S K^0_S ψ(3686)$ is studied by analyzing $e^+e^-$ collision data samples collected at eight center-of-mass energies ranging from 4.682 to 4.951 GeV with the BESIII detector operating at the BEPCII collider, corresponding to an integrated luminosity of $4.1~{\rm fb}^{-1}$. Observation of the $e^+e^-\to K^0_S K^0_S ψ(3686)$ process is found for the first time with a statistical significance of $6.3σ$, and the cross sections at each center-of-mass energy are measured. The ratio of cross sections of $e^+e^-\to K_S^0 K_S^0 ψ(3686)$ relative to $e^+e^-\to K^+ K^- ψ(3686)$ is determined to be $\frac{σ(e^+e^-\to K_S^0 K_S^0 ψ(3686))}{σ(e^+e^-\to K^+ K^- ψ(3686))}=0.45 \pm 0.25$, which is consistent with the prediction based on isospin symmetry. The uncertainty includes both statistical and systematic contributions. Additionally, the $K_S^0ψ(3686)$ invariant mass distribution is found to be consistent with three-body phase space. The significance of a contribution beyond three-body phase space is only $0.8σ$.

hep-ex↗

arXiv2025

Partial wave analysis of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$

Based on a sample of $(2712.4\pm14.3)\times10^6\;ψ(3686)$ events collected with the BESIII detector, a partial wave analysis of the decay $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is performed to investigate $Λ^*$ and $Σ^*$ resonances in the $π^0\barΣ^0$ and $π^0Λ$ invariant mass distributions. Significant contributions are found from the $Λ(1405)$, $Λ(1520)$, $Λ(1600)$, $Λ(1670)$, $Λ(1690)$, $Λ(1800)$, $Λ(1890)$, $Λ(2325)$, $Σ(1385)$, $Σ(1660)$, $Σ(1670)$, $Σ(1750)$, and $Σ(1910)$. The masses, widths, and production branching fractions for each component are determined. In addition, the branching fraction of $ψ(3686)\toΛ\barΣ^0π^0+c.c.$ is measured to be $(1.544\pm0.013\pm0.069)\times10^{-4}$ for the first time, where the first uncertainty is statistical and the second systematic.

hep-ex↗