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Guangyi Zhang

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32 publications

preprint2026arXiv

FL-Sailer: Efficient and Privacy-Preserving Federated Learning for Scalable Single-Cell Epigenetic Data Analysis via Adaptive Sampling

Single-cell ATAC-seq (scATAC-seq) enables high-resolution mapping of chromatin accessibility, yet privacy regulations and data size constraints hinder multi-institutional sharing. Federated learning (FL) offers a privacy-preserving alternative, but faces three fundamental barriers in scATAC-seq analysis: ultra-high dimensionality, extreme sparsity, and severe cross-institutional heterogeneity. We propose FL-Sailer, the first FL framework designed for scATAC-seq data. FL-Sailer integrates two key innovations: (i) adaptive leverage score sampling, which selects biologically interpretable features while reducing dimensionality by 80%, and (ii) an invariant VAE architecture, which disentangles biological signals from technical confounders via mutual information minimization. We provide a convergence guarantee, showing that FL-Sailer converges to an approximate solution of the original high-dimensional problem with bounded error. Extensive experiments on synthetic and real epigenomic datasets demonstrate that FL-Sailer not only enables previously infeasible multi-institutional collaborations but also surpasses centralized methods by leveraging adaptive sampling as an implicit regularizer to suppress technical noise. Our work establishes that federated learning, when tailored to domain-specific challenges, can become a superior paradigm for collaborative epigenomic research.

preprint2026arXiv

Quantize-Sample-and-Verify: LLM Acceleration via Adaptive Edge-Cloud Speculative Decoding

In edge-cloud speculative decoding (SD), edge devices equipped with small language models (SLMs) generate draft tokens that are verified by large language models (LLMs) in the cloud. A key bottleneck in such systems is the limited communication bandwidth between edge and cloud, which necessitates quantization of the information transmitted about generated tokens. In this work, we introduce a novel quantize-sample (Q-S) strategy that provably preserves the output distribution of the cloud-based model, ensuring that the verified tokens match the distribution of those that would have been generated directly by the LLM. We develop a throughput model for edge-cloud SD that explicitly accounts for communication latency. Leveraging this model, we propose an adaptive mechanism that optimizes token throughput by dynamically adjusting the draft length and quantization precision in response to both semantic uncertainty and channel conditions. Simulations demonstrate that the proposed Q-S approach significantly improves decoding efficiency in realistic edge-cloud deployment scenarios.

preprint2023arXiv

Ranking with submodular functions on the fly

Maximizing submodular functions have been studied extensively for a wide range of subset-selection problems. However, much less attention has been given to the role of submodularity in sequence-selection and ranking problems. A recently-introduced framework, named \emph{maximum submodular ranking} (MSR), tackles a family of ranking problems that arise naturally when resources are shared among multiple demands with different budgets. For example, the MSR framework can be used to rank web pages for multiple user intents. In this paper, we extend the MSR framework in the streaming setting. In particular, we consider two different streaming models and we propose practical approximation algorithms. In the first streaming model, called \emph{function arriving}, we assume that submodular functions (demands) arrive continuously in a stream, while in the second model, called \emph{item arriving}, we assume that items (resources) arrive continuously. Furthermore, we study the MSR problem with additional constraints on the output sequence, such as a matroid constraint that can ensure fair exposure among items from different groups. These extensions significantly broaden the range of problems that can be captured by the MSR framework. On the practical side, we develop several novel applications based on the MSR formulation, and empirically evaluate the performance of the proposed~methods.

preprint2022arXiv

A Unified Multi-Task Semantic Communication System with Domain Adaptation

The task-oriented semantic communication systems have achieved significant performance gain, however, the paradigm that employs a model for a specific task might be limited, since the system has to be updated once the task is changed or multiple models are stored for serving various tasks. To address this issue, we firstly propose a unified deep learning enabled semantic communication system (U-DeepSC), where a unified model is developed to serve various transmission tasks. To jointly serve these tasks in one model with fixed parameters, we employ domain adaptation in the training procedure to specify the task-specific features for each task. Thus, the system only needs to transmit the task-specific features, rather than all the features, to reduce the transmission overhead. Moreover, since each task is of different difficulty and requires different number of layers to achieve satisfactory performance, we develop the multi-exit architecture to provide early-exit results for relatively simple tasks. In the experiments, we employ a proposed U-DeepSC to serve five tasks with multi-modalities. Simulation results demonstrate that our proposed U-DeepSC achieves comparable performance to the task-oriented semantic communication system designed for a specific task with significant transmission overhead reduction and much less number of model parameters.

preprint2022arXiv

Coresets remembered and items forgotten: submodular maximization with deletions

In recent years we have witnessed an increase on the development of methods for submodular optimization, which have been motivated by the wide applicability of submodular functions in real-world data-science problems. In this paper, we contribute to this line of work by considering the problem of robust submodular maximization against unexpected deletions, which may occur due to privacy issues or user preferences. Specifically, we consider the minimum number of items an algorithm has to remember, in order to achieve a non-trivial approximation guarantee against adversarial deletion of up to dd items. We refer to the set of items that an algorithm has to keep before adversarial deletions as a deletion-robust coreset. Our theoretical contributions are two-fold. First, we propose a single-pass streaming algorithm that yields a (1−2ε)/(4p)(1-2ε)/(4p)-approximation for maximizing a non-decreasing submodular function under a general p-matroid constraint and requires a coreset of size k+d/εk + d/ε, where kk is the maximum size of a feasible solution. To the best of our knowledge, this is the first work to achieve an (asymptotically) optimal coreset, as no constant-factor approximation is possible with a coreset of size sublinear in dd. Second, we devise an effective offline algorithm that guarantees stronger approximation ratios with a coreset of size O(dlog⁡(k)/ε)O(d \log(k)/ε). We also demonstrate the superior empirical performance of the proposed algorithms in real-life applications.

preprint2022arXiv

Holistic Semi-Supervised Approaches for EEG Representation Learning

Recently, supervised methods, which often require substantial amounts of class labels, have achieved promising results for EEG representation learning. However, labeling EEG data is a challenging task. More recently, holistic semi-supervised learning approaches, which only require few output labels, have shown promising results in the field of computer vision. These methods, however, have not yet been adapted for EEG learning. In this paper, we adapt three state-of-the-art holistic semi-supervised approaches, namely MixMatch, FixMatch, and AdaMatch, as well as five classical semi-supervised methods for EEG learning. We perform rigorous experiments with all 8 methods on two public EEG-based emotion recognition datasets, namely SEED and SEED-IV. The experiments with different amounts of limited labeled samples show that the holistic approaches achieve strong results even when only 1 labeled sample is used per class. Further experiments show that in most cases, AdaMatch is the most effective method, followed by MixMatch and FixMatch.

preprint2022arXiv

Measurement of the D→K−π+π+π−D \to K^-π^+π^+π^- and D→K−π+π0D \to K^-π^+π^0 coherence factors and average strong-phase differences in quantum-correlated DDˉ{D\bar{D}} decays

The decays D→K−π+π+π−D\to K^-π^+π^+π^- and D→K−π+π0D \to K^-π^+π^0 are studied in a sample of quantum-correlated DDˉD\bar{D} pairs produced through the process e+e−→ψ(3770)→DDˉe^+e^- \to ψ(3770) \to D\bar{D}, exploiting a data set collected by the BESIII experiment that corresponds to an integrated luminosity of 2.93 fb−1^{-1}. Here DD indicates a quantum superposition of a D0D^0 and a Dˉ0\bar{D}^0 meson. By reconstructing one neutral charm meson in a signal decay, and the other in the same or a different final state, observables are measured that contain information on the coherence factors and average strong-phase differences of each of the signal modes. These parameters are critical inputs in the measurement of the angle γγ of the Unitarity Triangle in B−→DK−B^- \to DK^- decays at the LHCb and Belle II experiments. The coherence factors are determined to be RK3π=0.52−0.10+0.12R_{K3π}=0.52^{+0.12}_{-0.10} and RKππ0=0.78±0.04R_{Kππ^0}=0.78 \pm 0.04, with values for the average strong-phase differences that are δDK3π=(167−19+31)∘δ_D^{K3π}=\left(167^{+31}_{-19}\right)^\circ and δDKππ0=(196−15+14)∘δ_D^{Kππ^0}=\left(196^{+14}_{-15}\right)^\circ, where the uncertainties include both statistical and systematic contributions. The analysis is re-performed in four bins of the phase-space of the D→K−π+π+π−D \to K^-π^+π^+π^- to yield results that will allow for a more sensitive measurement of γγ with this mode, to which the BESIII inputs will contribute an uncertainty of around 6∘^\circ.

preprint2022arXiv

Ranking with submodular functions on a budget

Submodular maximization has been the backbone of many important machine-learning problems, and has applications to viral marketing, diversification, sensor placement, and more. However, the study of maximizing submodular functions has mainly been restricted in the context of selecting a set of items. On the other hand, many real-world applications require a solution that is a ranking over a set of items. The problem of ranking in the context of submodular function maximization has been considered before, but to a much lesser extent than item-selection formulations. In this paper, we explore a novel formulation for ranking items with submodular valuations and budget constraints. We refer to this problem as max-submodular ranking (MSR). In more detail, given a set of items and a set of non-decreasing submodular functions, where each function is associated with a budget, we aim to find a ranking of the set of items that maximizes the sum of values achieved by all functions under the budget constraints. For the MSR problem with cardinality- and knapsack-type budget constraints we propose practical algorithms with approximation guarantees. In addition, we perform an empirical evaluation, which demonstrates the superior performance of the proposed algorithms against strong baselines.

preprint2022arXiv

Robust Semantic Communications Against Semantic Noise

Although the semantic communications have exhibited satisfactory performance in a large number of tasks, the impact of semantic noise and the robustness of the systems have not been well investigated. Semantic noise is a particular kind of noise in semantic communication systems, which refers to the misleading between the intended semantic symbols and received ones. In this paper, we first propose a framework for the robust end-to-end semantic communication systems to combat the semantic noise. Particularly, we analyze the causes of semantic noise and propose a practical method to generate it. To remove the effect of semantic noise, adversarial training is proposed to incorporate the samples with semantic noise in the training dataset. Then, the masked autoencoder (MAE) is designed as the architecture of a robust semantic communication system, where a portion of the input is masked. To further improve the robustness of semantic communication systems, we firstly employ the vector quantization-variational autoencoder (VQ-VAE) to design a discrete codebook shared by the transmitter and the receiver for encoded feature representation. Thus, the transmitter simply needs to transmit the indices of these features in the codebook. Simulation results show that our proposed method significantly improves the robustness of semantic communication systems against semantic noise with significant reduction on the transmission overhead.

preprint2022arXiv

Search for new hadronic decays of hch_{c} and observation of hc→ppˉηh_{c}\to p\bar{p}η

A search for the hadronic decays of the hch_{c} meson to the final states ppˉπ+π−π0p\bar{p}π^{+}π^{-}π^{0}, ppˉηp\bar{p}η, and ppˉπ0p\bar{p}π^0 via the process ψ(3686)→π0hcψ(3686) \to π^{0}{h_c} is performed using (4.48±0.03)×108(4.48\pm0.03)\times10^{8} ψ(3686)ψ(3686) events collected with the BESIII detector. The decay channel hc→ppˉηh_{c}\to p\bar{p}η is observed for the first time with a significance greater than 5σ5σ and a branching fraction of (6.41±1.74±0.53±1.00)×10−4\left( {6.41 \pm 1.74 \pm 0.53 \pm 1.00} \right) \times {10^{ -4}}, where the uncertainties are statistical, systematic, and that from the branching fraction of ψ(3686)→π0hcψ(3686)\toπ^{0}h_{c}. Strong evidence for the decay hc→ppˉπ+π−π0{h_c} \to p\bar{p}{π^+}{π^-}{π^0} is found with a significance of 4.9σ4.9σ and a branching fraction of (3.84±0.83±0.69±0.58)×10−3\left( {3.84 \pm 0.83 \pm0.69} \pm 0.58 \right) \times {10^{ - 3}}. The significances include systematic uncertainties. No clear signal of the decay hc→ppˉπ0h_c\to p\bar{p}π^{0} is found, and an upper limit of 6.59×10−46.59\times 10^{-4} on its branching fraction is set at the 90% confidence level.

preprint2022arXiv

Search for the decay hc→π0J/ψh_c\rightarrowπ^0J/ψ

A search for the decay hc→π0J/ψh_c\rightarrowπ^0J/ψ is performed using a sample of hch_c produced in the reaction e+e−→π+π−hce^+e^-\rightarrowπ^+π^-h_c. The data samples were collected with the BESIII detector at center-of-mass energies between 4.189 and 4.437 GeV, corresponding to a total integrated luminosity of 11 fb−1^{-1}. No significant signal is observed. Upper limits on the branching ratio B(hc→π0J/ψ)/B(hc→γηc→γK+K−π0)\mathcal{B}(h_c\rightarrowπ^0J/ψ)/\mathcal{B}(h_c\rightarrowγη_c\rightarrowγK^+K^-π^0) and on the branching fraction B(hc→π0J/ψ)\mathcal{B}(h_c\rightarrowπ^0J/ψ) are determined to be 7.5×10−27.5\times10^{-2} and 4.7×10−44.7\times10^{-4} at 90%90\% confidence level, respectively. The latter is derived from the former using the measured branching fraction of the normalization channel. This is the first determination of the upper limit of the decay hc→π0J/ψh_c\rightarrowπ^0J/ψ.

preprint2021arXiv

Cross sections for the reactions e+e−→K+K−π+π−(π0)e^+e^-\rightarrow K^+K^-π^+π^-(π^0), K+K−K+K−(π0)K^+K^-K^+K^-(π^0), π+π−π+π−(π0)π^+π^-π^+π^-(π^0), ppˉπ+π−(π0)p\bar{p}π^+π^-(π^0) in the energy region between 3.773 and 4.600 GeV

Using the data samples collected in the energy range from 3.773 to 4.600 GeV with the BESIII detector at the BEPCII collider, we measure the dressed cross sections as a function of center-of-mass energy for e+e−→K+K−π+π−(π0)e^+e^-\rightarrow K^+K^-π^+π^-(π^0), K+K−K+K−(π0)K^+K^-K^+K^-(π^0), π+π−π+π−(π0)π^+π^-π^+π^-(π^0), and ppˉπ+π−(π0)p\bar{p}π^+π^-(π^0). The cross sections for e+e−→K+K−K+K−π0e^+e^-\rightarrow K^+K^-K^+K^-π^0, ppˉπ+π−(π0)p\bar{p}π^+π^-(π^0) are the first measurements. Cross sections for the other five channels are much more precise than previous results in this energy region. We also search for charmonium and charmonium-like resonances, such as the Y(4230)Y(4230), decaying into the same final states. We find evidence of the ψ(4040)ψ(4040) decaying to π+π−π+π−π0π^+π^-π^+π^-π^0 with a statistical significance of 3.6σ3.6σ. Upper limits are provided for other decays since no clear signals are observed.

preprint2021arXiv

Measurement of cross-section for e+e−→Ξ−Ξˉ+e^+e^-\toΞ^-\barΞ^+ near threshold at BESIII

The Born cross-sections and effective form factors for process e+e−→Ξ−Ξˉ+e^+e^-\toΞ^-\barΞ^+ are measured at eight center-of-mass energies between 2.644 and 3.080 GeV, using a total integrated luminosity of 363.9 pb−1^{-1} e+e−e^+e^- collision data collected with the BESIII detector at BEPCII. After performing a fit to the Born cross-section of e+e−→Ξ−Ξˉ+e^+e^-\toΞ^-\barΞ^+, no significant threshold effect is observed.

preprint2021arXiv

Measurement of the e+e−→Σ0Σˉ0e^{+}e^{-}\toΣ^{0}\barΣ^{0} cross sections at center-of-mass energies from 2.38642.3864 to 3.02003.0200 GeV

The Born cross sections of e+e−→Σ0Σˉ0e^{+}e^{-}\to Σ^{0}\barΣ^{0} are measured at center-of-mass energies from 2.38642.3864 to 3.02003.0200 GeV using data samples with an integrated luminosity of 328.5328.5 pb−1^{-1} collected with the BESIII detector operating at the BEPCII collider. The analysis makes use of a novel reconstruction method for energies near production threshold, while a single-tag method is employed at other center-of-mass energies. The measured cross sections are consistent with earlier results from BaBar, with a substantially improved precision. The cross-section lineshape can be well described by a perturbative QCD-driven energy function. In addition, the effective form factors of the Σ0Σ^{0} baryon are determined. The results provide precise experimental input for testing various theoretical predictions.

preprint2021arXiv

Measurements of e+e−→ηcπ+π−π0e^+e^-\rightarrow η_{\rm c}π^+ π^-π^0, ηcπ+π−η_{\rm c}π^+ π^- and ηcπ0γη_{\rm c}π^0γ at s\sqrt{s} from 4.18 to 4.60\,GeV, and search for a ZcZ_{\rm c} state close to the DDˉD\bar{D} threshold decaying to ηcπη_{\rm c}π at s\sqrt{s} = 4.23 GeV

We study ηcη_{\rm c} production at center-of-mass energies s\sqrt{s} from 4.18 to 4.60 GeV in e+e−e^+e^- annihilation data collected with the BESIII detector operating at the BEPCII storage ring, corresponding to 7.3 fb−1^{-1} of integrated luminosity. We measure the cross sections of the three different exclusive reactions e+e−→ηcπ+π−π0e^+e^-\rightarrow η_{\rm c}π^+ π^-π^0, e+e−→ηcπ+π−e^+e^- \rightarrow η_{\rm c}π^+ π^-, and e+e−→ηcπ0γe^+e^- \rightarrow η_{\rm c}π^0γ. We find significant ηcη_{\rm c} production in e+e−→ηcπ+π−π0e^+e^-\rightarrow η_{\rm c}π^+ π^-π^0 at s\sqrt{s} of 4.23 GeV and 4.26 GeV and observe a significant energy-dependent Born cross section that we measure to be consistent with the production via the intermediate Y(4260)Y(4260) resonance. In addition, we perform a search for a charmonium-like ZcZ_{\rm c} state close to the DDˉD\bar{D} threshold that decays to ηcπη_{\rm c}π, involving ground state charmonium, and observe no signal. Corresponding upper limits on the cross section of ηcη_{\rm c} and ZcZ_{\rm c} production are provided, where the yields are not found to be significant.

preprint2021arXiv

Model independent determination of the spin of the Ω−Ω^{-} and its polarization alignment in ψ(3686)→Ω−Ωˉ+ψ(3686)\rightarrowΩ^{-}\barΩ^{+}

We present an analysis of the process ψ(3686)→Ω−Ωˉ+ψ(3686) \to Ω^- \barΩ^+ (Ω−→K−ΛΩ^-\to K^-Λ, Ωˉ+→K+Λˉ\barΩ^+\to K^+\barΛ, Λ→pπ−Λ\to pπ^-, Λˉ→pˉπ+\barΛ\to \bar{p}π^+) based on a data set of 448×106448\times 10^6 ψ(3686)ψ(3686) decays collected with the BESIII detector at the BEPCII electron-positron collider. The helicity amplitudes for the process ψ(3686)→Ω−Ωˉ+ψ(3686) \to Ω^- \barΩ^+ and the decay parameters of the subsequent decay Ω−→K−ΛΩ^-\to K^-Λ (Ωˉ+→K+Λˉ)(\barΩ^+\to K^+\barΛ) are measured for the first time by a fit to the angular distribution of the complete decay chain. The branching fraction of ψ(3686)→Ω−Ωˉ+ψ(3686) \to Ω^- \barΩ^+ is measured to be (5.82±0.12±0.24)×10−5(5.82\pm 0.12\pm 0.24)\times 10^{-5}, with an improved precision compared to previous measurements.

preprint2021arXiv

Observation of e+e−→ηψ(2S)e^{+}e^{-}\rightarrowηψ(2S) at center-of-mass energies from 4.236 to 4.600 GeV

Using a total of 5.25 fb−15.25~{\rm fb}^{-1} of e+e−e^{+}e^{-} collision data with center-of-mass energies from 4.236 to 4.600 GeV, we report the first observation of the process e+e−→ηψ(2S)e^{+}e^{-}\to ηψ(2S) with a statistical significance of 5σ5σ. The data sets were collected by the BESIII detector operating at the BEPCII storage ring. We measure the yield of events integrated over center-of-mass energies and also present the energy dependence of the measured cross section.

preprint2021arXiv

Search for the X(2370)X(2370) and observation of ηc→ηηη′η_{c}\toηηη^\prime in J/ψ→γηηη′J/ψ\toγηηη^{\prime}

Using a sample of 1.31×109 J/ψ1.31\times10^{9} ~J/ψ events collected with the BESIII detector, we perform a study of J/ψ→γηηη′J/ψ\toγηηη^{\prime} to search for the X(2370)X(2370) and ηcη_{c} in the ηηη′ηηη^{\prime} invariant mass distribution. No significant signal for the X(2370)X(2370) is observed, and we set an upper limit for the product branching fraction of B(J/ψ→γX(2370)⋅B(X(2370)→ηηη′)<9.2×10−6{\cal B}(J/ψ\toγX(2370)\cdot{\cal B}(X(2370)\toηηη^{\prime}) < 9.2\times10^{-6} at the 90% confidence level. A clear ηcη_{c} signal is observed for the first time, yielding a product branching fraction of B(J/ψ→γηc)⋅B(ηc→ηηη′)=(4.86±0.62 (stat.)±0.45 (sys.))×10−5{\cal B}(J/ψ\to γη_{c})\cdot{\cal B}(η_{c}\to ηηη^{\prime}) = (4.86\pm0.62~({\rm stat.})\pm0.45~({\rm sys.}))\times10^{-5}.

preprint2021arXiv

Weak phases and CP-symmetry tests in sequential decays of entangled double-strange baryons

Using a sample of 1.31×1091.31\times10^9 J/ψJ/ψ events collected with the BESIII detector at the electron-positron collider BEPCII, we analyse the full J/ψ→J/ψ\to Ξ−Ξ‾+Ξ^-\overlineΞ^+, Ξ−→Λπ−Ξ^-\to Λπ^-, Λ→pπ−Λ\to pπ^-, Ξ‾+→Λ‾π+\overlineΞ^+\to\overlineΛπ^+, Λ‾→p‾π+\overlineΛ\to\overline{p}π^+ decay chain. A new method, exploiting the fact that the Ξ−Ξ‾+Ξ^-\overlineΞ^+ pair is entangled and sequentially decaying, and where the complete decay chains are reconstructed, is applied for the first time. This enables precision measurements of the decay parameters for the Ξ−→Λπ−Ξ^-\toΛπ^- decay (αΞα_Ξ, ϕΞϕ_Ξ) as well as the Ξ‾+→Λ‾π+\overlineΞ^+\to\overlineΛπ^+ decay (α‾Ξ\overlineα_Ξ, ϕ‾Ξ\overlineϕ_Ξ). From the decay parameters, two independent CP tests were performed, quantified by the observables ACPΞA_{\rm CP}^Ξ and ΔϕΞΔϕ_Ξ. Our results, ACPΞA_{\rm CP}^Ξ = (6.0±13.4±5.6)×10−3(6.0\pm13.4\pm5.6)\times10^{-3} and ΔϕΞ=(−4.8±13.7±2.9)×10−3 radΔϕ_Ξ= (-4.8\pm13.7\pm2.9)\times10^{-3}~{\rm rad}, are consistent with CP symmetry. Furthermore, our method enables a separation of strong and weak Ξ→ΛπΞ\toΛπ decay amplitudes. This results in the first direct measurement of the weak phase difference for any baryon decay. The result is found to be (ξP−ξS)=(1.2±3.4±0.8)×10−2(ξ_{P} - ξ_{S}) = (1.2\pm3.4\pm0.8)\times10^{-2} rad and is one of the most precise tests of CP symmetry for strange baryons. The strong phase difference is measured to be (δP−δS)=(−4.0±3.3±1.7)×10−2(δ_P - δ_S) = (-4.0\pm3.3\pm1.7)\times10^{-2} rad. In addition, we provide an independent measurement of the recently debated ΛΛ decay parameter, αΛ=0.757±0.011±0.008α_Λ = 0.757 \pm 0.011 \pm 0.008 . The ΛΛ‾Λ\overlineΛ asymmetry is measured to be ACPΛ=(−3.7±11.7±9.0)×10−3A_{\rm CP}^Λ = (-3.7\pm11.7\pm9.0)\times10^{-3}.

preprint2020arXiv

Σ+Σ^{+} and Σˉ−\barΣ^- polarization in the J/ψJ/ψ and ψ(3686)ψ(3686) decays

From 1310.6×1061310.6\times10^{6} J/ψJ/ψ and 448.1×106448.1\times10^{6} ψ(3686)ψ(3686) events collected with the BESIII experiment, we report the first observation of Σ+Σ^{+} and Σˉ−\barΣ^{-} spin polarization in e+e−→J/ψ(ψ(3686))→Σ+Σˉ−e^+e^-\rightarrow J/ψ(ψ(3686)) \rightarrow Σ^{+} \barΣ^{-} decays. The relative phases of the form factors ΔΦΔΦ have been measured to be (−15.5±0.7±0.5)∘(-15.5\pm0.7\pm0.5)^{\circ} and (21.7±4.0±0.8)∘(21.7\pm4.0\pm0.8)^{\circ} with J/ψJ/ψ and ψ(3686)ψ(3686) data, respectively. The non-zero value of ΔΦΔΦ allows for a direct and simultaneous measurement of the decay asymmetry parameters of Σ+→pπ0 (α0=−0.998±0.037±0.009)Σ^{+}\rightarrow p π^{0}~(α_0 = -0.998\pm0.037\pm0.009) and Σˉ−→pˉπ0 (αˉ0=0.990±0.037±0.011)\barΣ^{-}\rightarrow \bar{p} π^{0}~(\barα_0 = 0.990\pm0.037\pm0.011), the latter value being determined for the first time. The average decay asymmetry, (α0−αˉ0)/2(α_{0} - \barα_{0})/2, is calculated to be −0.994±0.004±0.002-0.994\pm0.004\pm0.002. The CP asymmetry ACP,Σ=(α0+αˉ0)/(α0−αˉ0)=−0.004±0.037±0.010A_{\rm CP,Σ} = (α_0 + \barα_0)/(α_0 - \barα_0) = -0.004\pm0.037\pm0.010 is extracted for the first time, and is found to be consistent with CP conservation.

preprint2020arXiv

Diverse Rule Sets

While machine-learning models are flourishing and transforming many aspects of everyday life, the inability of humans to understand complex models poses difficulties for these models to be fully trusted and embraced. Thus, interpretability of models has been recognized as an equally important quality as their predictive power. In particular, rule-based systems are experiencing a renaissance owing to their intuitive if-then representation. However, simply being rule-based does not ensure interpretability. For example, overlapped rules spawn ambiguity and hinder interpretation. Here we propose a novel approach of inferring diverse rule sets, by optimizing small overlap among decision rules with a 2-approximation guarantee under the framework of Max-Sum diversification. We formulate the problem as maximizing a weighted sum of discriminative quality and diversity of a rule set. In order to overcome an exponential-size search space of association rules, we investigate several natural options for a small candidate set of high-quality rules, including frequent and accurate rules, and examine their hardness. Leveraging the special structure in our formulation, we then devise an efficient randomized algorithm, which samples rules that are highly discriminative and have small overlap. The proposed sampling algorithm analytically targets a distribution of rules that is tailored to our objective. We demonstrate the superior predictive power and interpretability of our model with a comprehensive empirical study against strong baselines.

preprint2020arXiv

Erratum to "Measurement of the e+e−→π+π−e^+e^-\toπ^+π^- cross section between 600 and 900 MeV using initial state radiation"

In Phys. Lett. B 753, 629-638 (2016) [arXiv:1507.08188] the BESIII collaboration published a cross section measurement of the process e+e−→π+π−e^+e^-\to π^+ π^- in the energy range between 600 and 900 MeV. In this erratum we report a corrected evaluation of the statistical errors in terms of a fully propagated covariance matrix. The correction also yields a reduced statistical uncertainty for the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, which now reads as aμππ,LO(600−900 MeV)=(368.2±1.5stat±3.3syst)×10−10a_μ^{ππ\mathrm{, LO}}(600 - 900\,\mathrm{MeV}) = (368.2 \pm 1.5_{\rm stat} \pm 3.3_{\rm syst})\times 10^{-10}. The central values of the cross section measurement and of aμππ,LOa_μ^{ππ\mathrm{, LO}}, as well as the systematic uncertainties remain unchanged.

preprint2020arXiv

First Measurements of χcJ→Σ−Σˉ+(J=0,1,2)χ_{cJ}\rightarrow Σ^{-} \barΣ^{+} (J = 0, 1, 2) Decays

We measured the branching fractions of the decays χcJ→Σ−Σˉ+χ_{cJ}\toΣ^{-}\barΣ^{+} for the first time using the final states nnˉπ+π−n\bar{n}π^{+}π^{-}. The data sample exploited here is 448.1×106448.1\times10^{6} ψ(3686)ψ(3686) events collected with BESIII. We find B(χcJ→Σ−Σˉ+)=(51.3±2.4±4.1)×10−5, (5.7±1.4±0.6)×10−5, and (4.4±1.7±0.5)×10−5\mathcal{B}(χ_{cJ}\rightarrowΣ^{-}\barΣ^{+}) = (51.3\pm2.4\pm4.1)\times10^{-5},\, (5.7\pm1.4\pm0.6)\times10^{-5},\, \rm{and}~ (4.4\pm1.7\pm0.5)\times10^{-5}, for J=0,1,2J=0,1,2, respectively, where the first uncertainties are statistical and the second systematic.

preprint2020arXiv

Measurement of Singly Cabibbo-Suppressed Decays D→ωππD \to ωππ

Using 2.93 fb−1^{-1} of e+e−e^{+}e^{-} collision data taken at a center-of-mass energy of 3.773 GeV by the BESIII detector at the BEPCII, we measure the branching fractions of the singly Cabibbo-suppressed decays D→ωππD \to ωππ to be B(D0→ωπ+π−)=(1.33±0.16±0.12)×10−3\mathcal{B}(D^0 \to ωπ^+π^-) = (1.33 \pm 0.16 \pm 0.12)\times 10^{-3} and B(D+→ωπ+π0)=(3.87±0.83±0.25)×10−3\mathcal{B}(D^+ \to ωπ^+π^0) =(3.87 \pm 0.83 \pm 0.25)\times 10^{-3}, where the first uncertainties are statistical and the second ones systematic. The statistical significances are 12.9σ12.9σ and 7.7σ7.7 σ, respectively. The precision of B(D0→ωπ+π−)\mathcal{B}(D^0 \to ωπ^+π^-) is improved by a factor of 2.1 over the CLEO measurement, and B(D+→ωπ+π0)\mathcal{B}(D^+ \to ωπ^+π^0) is measured for the first time. No significant signal of B(D0→ωπ0π0)\mathcal{B}(D^0 \to ωπ^0π^0) is observed, and the upper limit on the branching fraction is B(D0→ωπ0π0)<1.10×10−3\mathcal{B}(D^0 \to ωπ^0π^0) < 1.10 \times 10^{-3} at the 90%90\% confidence level. The branching fractions of D→ηππD\to ηππ are also measured and consistent with existing results.

preprint2020arXiv

Measurement of the Born Cross Sections for e+e−→Ds+Ds1(2460)−+c.c.e^+e^-\to D_s^+ D_{s1}(2460)^- +c.c. and e+e−→Ds∗+Ds1(2460)−+c.c.e^+e^-\to D_s^{\ast +} D_{s1}(2460)^- +c.c.

The processes e+e−→Ds+Ds1(2460)−+c.c.e^+e^-\to D_s^+ D_{s1}(2460)^- +c.c. and e+e−→Ds∗+Ds1(2460)−+c.c.e^+e^-\to D_s^{\ast +} D_{s1}(2460)^- +c.c. are studied for the first time using data samples collected with the BESIII detector at the BEPCII collider. The Born cross sections of e+e−→Ds+Ds1(2460)−+c.c.e^+e^-\to D_s^+ D_{s1}(2460)^- +c.c. at nine center-of-mass energies between 4.467\,GeV and 4.600\,GeV and those of e+e−→Ds∗+Ds1(2460)−+c.c.e^+e^-\to D_s^{\ast +} D_{s1}(2460)^- +c.c. at s={\sqrt s}= 4.590\,GeV and 4.600\,GeV are measured. No obvious charmonium or charmonium-like structure is seen in the measured cross sections.

preprint2020arXiv

Observation of a resonant structure in e+e−→ωηe^{+}e^{-} \to ωη and another in e+e−→ωπ0e^{+}e^{-} \to ωπ^{0} at center-of-mass energies between 2.00 and 3.08 GeV

Born cross sections for the processes e+e−→ωηe^+e^- \to ωη and e+e−→ωπ0e^+e^- \to ωπ^{0} have been determined for center-of-mass energies between 2.00 and 3.08 GeV with the BESIII detector at the BEPCII collider. The results obtained in this work are consistent with previous measurements but with improved precision. Two resonant structures are observed. In the e+e−→ωηe^{+}e^{-} \to ωη cross sections, a resonance with a mass of (2179±21±3)MeV/c2(2179 \pm 21 \pm 3)\text{MeV}/c^2 and a width of (89±28±5)MeV(89 \pm 28 \pm 5)\text{MeV} is observed with a significance of 6.1σσ. Its properties are consistent with the ϕ(2170)ϕ(2170). In the e+e−→ωπ0e^{+}e^{-} \toωπ^{0} cross sections, a resonance denoted Y(2040)Y(2040) is observed with a significance of more than 10σσ. Its mass and width are determined to be (2034±13±9)MeV/c2(2034 \pm 13 \pm 9)\text{MeV}/c^2 and (234±30±25)MeV(234 \pm 30 \pm 25)\text{MeV}, respectively, where the first uncertainties are statistical and the second ones are systematic.

preprint2020arXiv

Observation of the Y(4220)Y(4220) and Y(4360)Y(4360) in the process e+e−→ηJ/ψe^{+}e^{-} \to ηJ/ψ

The cross sections of the process e+e−→ηJ/ψe^{+}e^{-} \to ηJ/ψ at center-of-mass energies (s\sqrt{s}) between 3.81 and 4.60 GeV are measured with high precision by using data samples collected with the BESIII detector operating at the BEPCII storage ring. Three structures are observed by analyzing the lineshape of the measured cross sections, and a maximum-likelihood fit including three resonances is performed by assuming the lowest lying structure is the ψ(4040)ψ(4040). For the other resonances, we obtain masses of (4218.7±4.0±2.5)(4218.7 \pm 4.0 \pm 2.5) and (4380.4±14.2±1.8)(4380.4 \pm 14.2 \pm 1.8) MeV/c2^{2} with corresponding widths of (82.5±5.9±0.5)(82.5 \pm 5.9 \pm 0.5) and (147.0±63.0±25.8)(147.0 \pm 63.0 \pm 25.8) MeV, respectively, where the first uncertainties are statistical and the second ones systematic. The measured resonant parameters are consistent with those of the Y(4220)Y(4220) and Y(4360)Y(4360) from pr evious measurements of different final states. For the first time, we observe the decays of the Y(4220)Y(4220) and Y(4360)Y(4360) into ηJ/ψηJ/ψ final states.

preprint2020arXiv

Search for New Hadronic Decays of hch_c and Observation of hc→K+K−π+π−π0h_c\rightarrow K^{+}K^{-}π^{+}π^{-}π^{0}

Ten hadronic final states of the hch_c decays are investigated via the process ψ(3686)→π0hcψ(3686)\rightarrow π^0 h_c, using a data sample of (448.1±2.9)×106(448.1 \pm 2.9) \times 10^6 ψ(3686)ψ(3686) events collected with the BESIII detector. The decay channel hc→K+K−π+π−π0h_c\rightarrow K^{+}K^{-}π^{+}π^{-}π^{0} is observed for the first time with a significance of 6.0σ6.0 σ. The corresponding branching fraction is determined to be B(hc→K+K−π+π−π0)=(3.3±0.6±0.6)×10−3\mathcal{B}(h_c\rightarrow K^{+}K^{-}π^{+}π^{-}π^{0}) =(3.3 \pm 0.6 \pm 0.6)\times 10^{-3} (the first uncertainty is statistical and the second systematical). Evidence for the decays hc→π+π−π0ηh_c\rightarrow π^{+} π^{-} π^{0} η and hc→KS0K±π∓π+π−h_c\rightarrow K^{0}_{S}K^{\pm}π^{\mp}π^{+}π^{-} is found with a significance of 3.6σ3.6 σ and 3.8σ3.8 σ, respectively. The corresponding branching fractions (and upper limits) are obtained to be B(hc→π+π−π0η)=(7.2±1.8±1.3)×10−3\mathcal{B}(h_c\rightarrow π^{+} π^{-} π^{0} η) =(7.2 \pm 1.8 \pm 1.3)\times 10^{-3} (<1.8×10−2)(< 1.8 \times 10^{-2}) and B(hc→KS0K±π∓π+π−)=(2.8±0.9±0.5)×10−3\mathcal{B}(h_c\rightarrow K^{0}_{S}K^{\pm}π^{\mp}π^{+}π^{-}) =(2.8 \pm 0.9 \pm 0.5)\times 10^{-3} (<4.7×10−3)(<4.7\times 10^{-3}). Upper limits on the branching fractions for the final states hc→K+K−π0h_c \rightarrow K^{+}K^{-}π^{0}, K+K−ηK^{+}K^{-}η, K+K−π+π−ηK^{+}K^{-}π^{+}π^{-}η, 2(K+K−)π02(K^{+}K^{-})π^{0}, K+K−π0ηK^{+}K^{-}π^{0}η, KS0K±π∓K^{0}_{S}K^{\pm}π^{\mp}, and ppˉπ0π0p\bar{p}π^{0}π^{0} are determined at a confidence level of 90\%.

preprint2020arXiv

Search for the decay J/ψ→γ+invisibleJ/ψ\toγ+ \rm {invisible}

We search for J/ψJ/ψ radiative decays into a weakly interacting neutral particle, namely an invisible particle, using the J/ψJ/ψ produced through the process ψ(3686)→π+π−J/ψψ(3686)\toπ^+π^-J/ψ in a data sample of (448.1±2.9)×106(448.1\pm2.9)\times 10^6 ψ(3686)ψ(3686) decays collected by the BESIII detector at BEPCII. No significant signal is observed. Using a modified frequentist method, upper limits on the branching fractions are set under different assumptions of invisible particle masses up to 1.2  GeV/c2\mathrm{\ Ge\kern -0.1em V}/c^2. The upper limit corresponding to an invisible particle with zero mass is 7.0×10−7\times 10^{-7} at the 90\% confidence level.

preprint2020arXiv

Search for the semileptonic decay D0(+)→b1(1235)−(0)e+νeD^{0(+)}\to b_1(1235)^{-(0)} e^+ν_e

Using 2.93 fb−12.93~\mathrm{fb}^{-1} of e+e−e^+e^- annihilation data collected at a center-of-mass energy s=3.773\sqrt{s}=3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the semileptonic D0(+)D^{0(+)} decays into a b1(1235)−(0)b_1(1235)^{-(0)} axial-vector meson for the first time. No significant signal is observed for either charge combination. The upper limits on the product branching fractions are BD0→b1(1235)−e+νe⋅Bb1(1235)−→ωπ−<1.12×10−4{\mathcal B}_{D^0\to b_1(1235)^- e^+ν_e}\cdot {\mathcal B}_{b_1(1235)^-\to ωπ^-}<1.12\times 10^{-4} and BD+→b1(1235)0e+νe⋅Bb1(1235)0→ωπ0<1.75×10−4{\mathcal B}_{D^+\to b_1(1235)^0 e^+ν_e}\cdot {\mathcal B}_{b_1(1235)^0\to ωπ^0}<1.75\times 10^{-4} at the 90\% confidence level.

preprint2020arXiv

Study of BESIII Trigger Efficiencies with the 2018 J/ψJ/ψ Data

Using a dedicated data sample taken in 2018 on the J/ψJ/ψ peak, we perform a detailed study of the trigger efficiencies of the BESIII detector. The efficiencies are determined from three representative physics processes, namely Bhabha-scattering, dimuon production and generic hadronic events with charged particles. The combined efficiency of all active triggers approaches 100%100\% in most cases with uncertainties small enough as not to affect most physics analyses.

preprint2020arXiv

Study of open-charm decays and radiative transitions of the X(3872)

The processes X(3872)→D∗0D0ˉ+c.c., γJ/ψ, γψ(2S),X(3872)\to D^{*0}\bar{D^{0}}+c.c.,~γJ/ψ,~γψ(2S), and γD+D−γD^{+}D^{-} are searched for in a 9.0 fb−19.0~\rm fb^{-1} data sample collected at center-of-mass energies between 4.1784.178 and 4.2784.278 GeV with the BESIII detector. We observe X(3872)→D∗0D0ˉ+c.c.X(3872)\to D^{*0}\bar{D^{0}}+c.c. and find evidence for X(3872)→γJ/ψX(3872)\toγJ/ψ with statistical significances of 7.4σ7.4σ and 3.5σ3.5σ, respectively. No evident signals for X(3872)→γψ(2S)X(3872)\toγψ(2S) and γD+D−γD^{+}D^{-} are found, and upper limit on the relative branching ratio Rγψ≡B(X(3872)→γψ(2S))B(X(3872)→γJ/ψ)<0.59R_{γψ} \equiv\frac{\mathcal{B}(X(3872)\toγψ(2S))}{\mathcal{B}(X(3872)\toγJ/ψ)}<0.59 is set at 90%\% confidence level. Measurements of branching ratios relative to decay X(3872)→π+π−J/ψX(3872)\toπ^+π^- J/ψ are also reported for decays X(3872)→D∗0D0ˉ+c.c., γψ(2S), γJ/ψX(3872)\to D^{*0}\bar{D^{0}}+c.c., ~γψ(2S),~γJ/ψ, γD+D−γD^{+}D^{-}, as well as the non-D∗0Dˉ0D^{*0}\bar{D}^{0} three-body decays π0D0Dˉ0π^0 D^{0}\bar{D}^{0} and γD0Dˉ0γD^{0}\bar{D}^{0}.

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