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Xiaoyu Li

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60works
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Published work

60 publications

preprint2026arXiv

AgentEscapeBench: Evaluating Out-of-Domain Tool-Grounded Reasoning in LLM Agents

As LLM-based agents increasingly rely on external tools, it is important to evaluate their ability to sustain tool-grounded reasoning beyond familiar workflows and short-range interactions. We introduce AgentEscapeBench, an escape-room-style benchmark that tests whether agents can infer, execute, and revise novel tool-use procedures under explicit long-range dependency constraints. Each task defines a directed acyclic dependency graph over tools and items, requiring agents to invoke real external functions, track hidden state revealed incrementally, propagate intermediate results, and submit a deterministically verifiable final answer. AgentEscapeBench includes 270 instances across five difficulty tiers and supports fully automated evaluation. Experiments with sixteen LLM agents and human participants show that performance drops sharply as dependency depth increases: humans decline from 98.3% success at difficulty-5 to 80.0% at difficulty-25, while the best model drops from 90.0% to 60.0%. Trajectory analysis attributes model failures mainly to breakdowns in long-range state tracking, clue adherence, and intermediate-result propagation. These findings suggest that current agents can often handle local tool use but still struggle with deep contextual dependencies. We hope AgentEscapeBench can serve as a diagnostic testbed for measuring current agent capabilities and informing future training efforts toward more robust general-purpose reasoning, action, and adaptation.

preprint2026arXiv

AnyBand-Diff: A Unified Remote Sensing Image Generation and Band Repair Framework with Spectral Priors

Existing diffusion models have made significant progress in generating realistic images. However, their direct adaptation to remote sensing imagery often disregards intrinsic physical laws. This oversight frequently leads to spectral distortion and radiometric inconsistency, severely limiting the scientific utility of generated data. To address this issue, this paper introduces AnyBand-Diff, a novel spectral-prior-guided diffusion framework tailored for robust spectral reconstruction. Specifically, we design a Masked Conditional Diffusion backbone integrated with a dual stochastic masking strategy, empowering the model to recover complete spectral information from arbitrary band subsets. Subsequently, to ensure radiometric fidelity, a Physics-Guided Sampling mechanism is proposed, leveraging gradients from a differentiable physical model to explicitly steer the denoising trajectory toward the manifold of physically plausible solutions. Furthermore, a Multi-Scale Physical Loss is formulated to enforce rigorous constraints across pixel, region, and global levels in a joint manner. Extensive experiments confirm the effectiveness of AnyBand-Diff in generating reliable imagery and achieving accurate spectral reconstruction, contributing to the advancement of physics-aware generative methods for Earth observation.

preprint2026arXiv

Contrastive Identification and Generation in the Limit

In the classical identification in the limit model of Gold [1967], a stream of positive examples is presented round by round, and the learner must eventually recover the target hypothesis. Recently, Kleinberg and Mullainathan [2024] introduced generation in the limit, where the learner instead must eventually output novel elements of the target's support. Both lines of work focus on positive-only or fully labeled data. Yet many natural supervision signals are inherently relational rather than singleton, which encode relationships between examples rather than labels of individual ones. We initiate the study of contrastive identification and generation in the limit, where the learner observes a contrastive presentation of data: a stream of unordered pairs {x,y}\{x,y\} satisfying h(x)≠h(y)h(x)\ne h(y) for an unknown target binary hypothesis hh, but which element is positive is hidden from the learner. We first present three results in the noiseless setting: an exact characterization of contrastive identifiable classes (a one-line geometric refinement of Angluin [1980]'s tell-tale condition), a combinatorial dimension called contrastive closure dimension (a contrasitive analogue of the closure dimension in Raman et al. [2025]) and exactly characterizing uniform contrastive generation with tight sample complexity, and a strict hierarchy in which contrastive generation and text identification are mutually incomparable. We then prove a sharp reversal under finite adversarial corruption: there exist classes identifiable from contrastive pairs under any finite corruption budget by a single budget-independent algorithm, yet not identifiable from positive examples under even one corrupted observation. The unifying technical object is the common crossing graph, which encodes pairwise ambiguity, family-level generation obstructions, and corruption defects in a single coverage-and-incidence language.

preprint2026arXiv

D2-CDIG: Controlled Diffusion Remote Sensing Image Generation with Dual Priors of DEM and Cloud-Fog

Remote sensing image generation provides a reliable data foundation for remote sensing large models and downstream tasks. However, existing controllable remote sensing image generation methods typically rely on traditional techniques such as segmentation and edge detection, which do not fully leverage terrain or atmospheric conditions. As a result, the generated images often lack accuracy and naturalness when dealing with complex terrains and atmospheric phenomena. In this paper, we propose a novel remote sensing image generation framework, D2-CDIG, which integrates diffusion models with a dual-prior control mechanism. By incorporating both Digital Elevation Model (DEM) and cloud-fog information as dual prior knowledge, D2-CDIG precisely controls ground features and atmospheric phenomena within the generated images. Specifically, D2-CDIG decouples the terrain and atmospheric generation processes through independent control of ground and atmospheric branches. Additionally, a refined cloud-fog slider is introduced to flexibly adjust cloud thickness and distribution. During training, ground and atmospheric control signals are injected in layers to ensure a seamless transition within the images. Compared to traditional methods based on segmentation or edge detection, D2-CDIG shows significant improvements in image quality, detail richness, and realism. D2-CDIG offers a flexible and precise solution for remote sensing image generation, providing high-quality data for training large remote sensing models and downstream tasks.

preprint2026arXiv

HeavySkill: Heavy Thinking as the Inner Skill in Agentic Harness

Recent advances in agentic harness with orchestration frameworks that coordinate multiple agents with memory, skills, and tool use have achieved remarkable success in complex reasoning tasks. However, the underlying mechanism that truly drives performance remains obscured behind intricate system designs. In this paper, we propose HeavySkill, a perspective that views heavy thinking not only as a minimal execution unit in orchestration harness but also as an inner skill internalized within the model's parameters that drives the orchestrator to solve complex tasks. We identify this skill as a two-stage pipeline, i.e., parallel reasoning then summarization, which can operate beneath any agentic harness. We present a systematic empirical study of HeavySkill across diverse domains. Our results show that this inner skill consistently outperforms traditional Best-of-N (BoN) strategies; notably, stronger LLMs can even approach Pass@N performance. Crucially, we demonstrate that the depth and width of heavy thinking, as a learnable skill, can be further scaled via reinforcement learning, offering a promising path toward self-evolving LLMs that internalize complex reasoning without relying on brittle orchestration layers.

preprint2026arXiv

SOP-Maze: Evaluating Large Language Models on Complicated Business Standard Operating Procedures

As large language models (LLMs) are widely deployed as domain-specific agents, many benchmarks have been proposed to evaluate their ability to follow instructions and make decisions in real-world scenarios. However, business scenarios often involve complex standard operating procedures (SOPs), and the evaluation of LLM capabilities in such contexts has not been fully explored. To bridge this gap, we propose SOP-Maze, a benchmark constructed from real-world business data and adapted into a collection of 397 instances and 3422 subtasks from 23 complex SOP scenarios. We further categorize SOP tasks into two broad classes: Lateral Root System (LRS), representing wide-option tasks that demand precise selection; and Heart Root System (HRS), which emphasizes deep logical reasoning with complex branches. Extensive experiments reveal that nearly all state-of-the-art models struggle with SOP-Maze. We conduct a comprehensive analysis and identify three key error categories: (i) route blindness: difficulty following procedures; (ii) conversational fragility: inability to handle real dialogue nuances; and (iii) calculation errors: mistakes in time or arithmetic reasoning under complex contexts. The systematic study explores LLM performance across SOP tasks that challenge both breadth and depth, offering new insights for improving model capabilities. We have open-sourced our work on: https://github.com/meituan-longcat/SOP-Maze.

preprint2025arXiv

UniHetero: Could Generation Enhance Understanding for Vision-Language-Model at Large Data Scale?

Vision-language large models are moving toward the unification of visual understanding and visual generation tasks. However, whether generation can enhance understanding is still under-explored on large data scale. In this work, we analysis the unified structure with a concise model, UniHetero, under large-scale pretraining (>200M samples). Our key observations are: (1) Generation can improve understanding, but Only if you generate Semantics, Not Pixels. A common assumption in unified vision-language models is that adding generation will naturally strengthen understanding. However, this is not always true at scale. At 200M+ pretraining samples, generation helps understanding only when it operates at the semantic level, i.e. when the model learns to autoregress high-level visual representations inside the LLM. Once pixel-level objectives (e.g., diffusion losses) directly interfere with the LLM, understanding performance often degrades. (2) Generation reveals a superior Data Scaling trend and higher Data Utilization. Unified generation-understanding demonstrates a superior scaling trend compared to understanding alone, revealing a more effective way to learn vision-only knowledge directive from vision modality rather than captioning to text. (3) Autoregression on Input Embedding is effective to capture visual details. Compared to the commonly-used vision encoder, make visual autoregression on input embedding shows less cumulative error and is modality independent, which can be extend to all modalities. The learned semantic representations capture visual information such as objects, locations, shapes, and colors; further enable pixel-level image generation.

preprint2024arXiv

Investigation of the ΔI=1/2ΔI = 1/2 rule and test of CP violation through the measurement of decay asymmetry parameters in Ξ−Ξ^- decays

Using (10087±44)×106(10087\pm44)\times 10^{6} J/ψJ/ψ events collected with the BESIII detector, numerous Ξ−Ξ^- and ΛΛ decay asymmetry parameters are simultaneously determined from the process J/ψ→Ξ−Ξˉ+→Λ(pπ−)π−Λˉ(nˉπ0)π+J/ψ\to Ξ^- \barΞ^+ \to Λ(pπ^-) π^- \barΛ(\bar{n} π^0) π^+ and its charge-conjugate channel. The precisions of α0α_0 for Λ→nπ0Λ\to nπ^0 and αˉ0\barα_0 for Λˉ→nˉπ0\barΛ \to \bar{n}π^0 compared to world averages are improved by factors of 4 and 1.7, respectively. The ratio of decay asymmetry parameters of Λ→nπ0Λ\to nπ^0 to that of Λ→pπ−Λ\to pπ^-, ⟨α0⟩/⟨αΛ−⟩\langle α_0 \rangle/ \langle α_{Λ-} \rangle , is determined to be 0.873±0.012−0.010+0.011 0.873 \pm 0.012^{+0.011}_{-0.010}, where the first and the second uncertainties are statistical and systematic, respectively. The ratio is smaller than unity more than 5σ5σ, which signifies the existence of the ΔI=3/2ΔI = 3/2 transition in ΛΛ for the first time. Beside, we test for CP violation in Ξ−→Λπ−Ξ^- \to Λπ^- and in Λ→nπ0Λ\to n π^{0} with the best precision to date.

preprint2023arXiv

Search for hidden-charm tetraquark with strangeness in e+e−→K+Ds∗−D∗0+c.c.e^{+}e^{-}\rightarrow K^+ D_{s}^{*-} D^{*0}+c.c.

We report a search for a heavier partner of the recently observed Zcs(3985)−Z_{cs}(3985)^{-} state, denoted as Zcs′−Z_{cs}^{\prime -}, in the process e+e−→K+Ds∗−D∗0+c.c.e^{+} e^{-}\rightarrow K^{+}D_{s}^{*-}D^{* 0}+c.c., based on e+e−e^+e^- collision data collected at the center-of-mass energies of s=4.661\sqrt{s}=4.661, 4.682 and 4.699 GeV with the BESIII detector. The Zcs′−Z_{cs}^{\prime -} is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark. A partial-reconstruction technique is used to isolate K+K^+ recoil-mass spectra, which are probed for a potential contribution from Zcs′−→Ds∗−D∗0Z_{cs}^{\prime -}\to D_{s}^{*-}D^{* 0} (c.c.c.c.). We find an excess of Zcs′−→Ds∗−D∗0Z_{cs}^{\prime -}\rightarrow D_{s}^{*-}D^{*0} (c.c.c.c.) candidates with a significance of 2.1σ2.1σ, after considering systematic uncertainties, at a mass of (4123.5±0.7stat.±4.7syst.) MeV/c2(4123.5\pm0.7_\mathrm{stat.}\pm4.7_\mathrm{syst.})\ \mathrm{MeV}/c^{2}. As the data set is limited in size, the upper limits are evaluated at the 90\% confidence level on the product of the Born cross sections (σBornσ^{\mathrm{Born}}) and the branching fraction (B\mathcal{B}) of Zcs′−→Ds∗−D∗0Z_{cs}^{\prime-}\rightarrow D_{s}^{*-}D^{* 0}, under different assumptions of the Zcs′−Z_{cs}^{\prime -} mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies. The upper limits of σBorn⋅Bσ^{\rm Born}\cdot\mathcal{B} are found to be at the level of O(1)\mathcal{O}(1) pb at each energy. Larger data samples are needed to confirm the Zcs′−Z_{cs}^{\prime -} state and clarify its nature in the coming years.

preprint2022arXiv

Amplitude analysis and branching fraction measurement of the decay Ds+→K+π+π−D_{s}^{+} \to K^+π^+π^-

Using 6.326.32 fb−1^{-1} of e+e−e^{+}e^{-} collision data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay Ds+→K+π+π−D^+_s \to K^+π^+π^- and determine the amplitudes of the various intermediate states. The absolute branching fraction of Ds+→K+π+π−D^+_s\to K^+π^+π^- is measured to be (6.11±0.18stat.±0.11syst.)×10−36.11\pm0.18_{\rm stat.}\pm0.11_{\rm syst.})\times 10^{-3}. The branching fractions of the dominant intermediate processes Ds+→K+ρ0,ρ0→π+π−D_{s}^{+} \to K^+ρ^0, ρ^0 \to π^+π^- and Ds+→K∗(892)0π+,K∗(892)0→K+π−D_{s}^{+} \to K^*(892)^0π^+, K^*(892)^0 \to K^+π^- are determined to be (1.96±0.19stat.±0.23syst.)×10−3(1.96\pm0.19_{\rm stat.}\pm0.23_{\rm syst.})\times 10^{-3} and (1.85±0.12stat.±0.13syst.)×10−3(1.85\pm0.12_{\rm stat.}\pm0.13_{\rm syst.})\times 10^{-3}, respectively. The intermediate resonances f0(500)f_0(500), f0(980)f_0(980), and f0(1370)f_0(1370) are observed for the first time in this channel.

preprint2022arXiv

Amplitude analysis and branching-fraction measurement of Ds+→π+π0η′D_{s}^{+} \to π^{+}π^{0}η^{\prime}

Using data collected with the BESIII detector in e+e−e^+e^- collisions at center-of-mass energies between 4.178 and 4.226 GeV and corresponding to 6.32~fb−1^{-1} of integrated luminosity, we report the amplitude analysis and branching-fraction measurement of the Ds+→π+π0η′D^+_s \to π^+ π^0 η^{\prime} decay. We find that the dominant intermediate process is Ds+→ρ+η′D^+_s \toρ^+ η^{\prime} and the significances of other resonant and nonresonant processes are all less than 3σ3σ. The upper limits on the branching fractions of SS-wave and PP-wave nonresonant components are set to 0.10%0.10\% and 0.74%0.74\% at the 90%90\% confidence level, respectively. In addition, the branching fraction of the Ds+→π+π0η′D^+_s \to π^+ π^0 η^{\prime} decay is measured to be (6.15±0.25(stat.)±0.18(syst.))%(6.15\pm0.25(\rm stat.)\pm0.18(\rm syst.))\%, which receives significant contribution only from Ds+→ρ+η′D_s^+\to ρ^+η^{\prime} according to the amplitude analysis.

preprint2022arXiv

CAMO-MOT: Combined Appearance-Motion Optimization for 3D Multi-Object Tracking with Camera-LiDAR Fusion

3D Multi-object tracking (MOT) ensures consistency during continuous dynamic detection, conducive to subsequent motion planning and navigation tasks in autonomous driving. However, camera-based methods suffer in the case of occlusions and it can be challenging to accurately track the irregular motion of objects for LiDAR-based methods. Some fusion methods work well but do not consider the untrustworthy issue of appearance features under occlusion. At the same time, the false detection problem also significantly affects tracking. As such, we propose a novel camera-LiDAR fusion 3D MOT framework based on the Combined Appearance-Motion Optimization (CAMO-MOT), which uses both camera and LiDAR data and significantly reduces tracking failures caused by occlusion and false detection. For occlusion problems, we are the first to propose an occlusion head to select the best object appearance features multiple times effectively, reducing the influence of occlusions. To decrease the impact of false detection in tracking, we design a motion cost matrix based on confidence scores which improve the positioning and object prediction accuracy in 3D space. As existing multi-object tracking methods only consider a single category, we also propose to build a multi-category loss to implement multi-object tracking in multi-category scenes. A series of validation experiments are conducted on the KITTI and nuScenes tracking benchmarks. Our proposed method achieves state-of-the-art performance and the lowest identity switches (IDS) value (23 for Car and 137 for Pedestrian) among all multi-modal MOT methods on the KITTI test dataset. And our proposed method achieves state-of-the-art performance among all algorithms on the nuScenes test dataset with 75.3% AMOTA.

preprint2022arXiv

Cross section measurements of the processes e+e−→ωπ0e^+e^- \rightarrow ωπ^{0} and ωηωη at center-of-mass energies between 3.773 and 4.701 GeV

The Born cross sections of the processes e+e−→ωπ0e^+e^- \rightarrow ωπ^{0} and e+e−→ωηe^+e^- \rightarrow ωη are measured at center-of-mass energies between 3.773 and 4.701 GeV using a total integrated luminosity of 22.7 fb−1^{-1} collected with the BESIII detector operating at the BEPCII collider. A simple s−ns^{-n} dependence for the continuum process can describe the measured Born cross sections. No significant contributions from the ψ(4160)ψ(4160), Y(4230)Y(4230), Y(4360)Y(4360), ψ(4415)ψ(4415), Y(4660)Y(4660) resonances are found, which indicates relative small branching fractions for these resonances into the ωπ0ωπ^{0} and ωηωη final states.

preprint2022arXiv

Deblur-NeRF: Neural Radiance Fields from Blurry Images

Neural Radiance Field (NeRF) has gained considerable attention recently for 3D scene reconstruction and novel view synthesis due to its remarkable synthesis quality. However, image blurriness caused by defocus or motion, which often occurs when capturing scenes in the wild, significantly degrades its reconstruction quality. To address this problem, We propose Deblur-NeRF, the first method that can recover a sharp NeRF from blurry input. We adopt an analysis-by-synthesis approach that reconstructs blurry views by simulating the blurring process, thus making NeRF robust to blurry inputs. The core of this simulation is a novel Deformable Sparse Kernel (DSK) module that models spatially-varying blur kernels by deforming a canonical sparse kernel at each spatial location. The ray origin of each kernel point is jointly optimized, inspired by the physical blurring process. This module is parameterized as an MLP that has the ability to be generalized to various blur types. Jointly optimizing the NeRF and the DSK module allows us to restore a sharp NeRF. We demonstrate that our method can be used on both camera motion blur and defocus blur: the two most common types of blur in real scenes. Evaluation results on both synthetic and real-world data show that our method outperforms several baselines. The synthetic and real datasets along with the source code is publicly available at https://limacv.github.io/deblurnerf/

preprint2022arXiv

FDNeRF: Few-shot Dynamic Neural Radiance Fields for Face Reconstruction and Expression Editing

We propose a Few-shot Dynamic Neural Radiance Field (FDNeRF), the first NeRF-based method capable of reconstruction and expression editing of 3D faces based on a small number of dynamic images. Unlike existing dynamic NeRFs that require dense images as input and can only be modeled for a single identity, our method enables face reconstruction across different persons with few-shot inputs. Compared to state-of-the-art few-shot NeRFs designed for modeling static scenes, the proposed FDNeRF accepts view-inconsistent dynamic inputs and supports arbitrary facial expression editing, i.e., producing faces with novel expressions beyond the input ones. To handle the inconsistencies between dynamic inputs, we introduce a well-designed conditional feature warping (CFW) module to perform expression conditioned warping in 2D feature space, which is also identity adaptive and 3D constrained. As a result, features of different expressions are transformed into the target ones. We then construct a radiance field based on these view-consistent features and use volumetric rendering to synthesize novel views of the modeled faces. Extensive experiments with quantitative and qualitative evaluation demonstrate that our method outperforms existing dynamic and few-shot NeRFs on both 3D face reconstruction and expression editing tasks. Code is available at https://github.com/FDNeRF/FDNeRF.

preprint2022arXiv

FENeRF: Face Editing in Neural Radiance Fields

Previous portrait image generation methods roughly fall into two categories: 2D GANs and 3D-aware GANs. 2D GANs can generate high fidelity portraits but with low view consistency. 3D-aware GAN methods can maintain view consistency but their generated images are not locally editable. To overcome these limitations, we propose FENeRF, a 3D-aware generator that can produce view-consistent and locally-editable portrait images. Our method uses two decoupled latent codes to generate corresponding facial semantics and texture in a spatial aligned 3D volume with shared geometry. Benefiting from such underlying 3D representation, FENeRF can jointly render the boundary-aligned image and semantic mask and use the semantic mask to edit the 3D volume via GAN inversion. We further show such 3D representation can be learned from widely available monocular image and semantic mask pairs. Moreover, we reveal that joint learning semantics and texture helps to generate finer geometry. Our experiments demonstrate that FENeRF outperforms state-of-the-art methods in various face editing tasks.

preprint2022arXiv

First Observation of the Semileptonic Decay Λc+→pK−e+νeΛ_c^+\rightarrow pK^- e^+ν_e

Using 4.5 fb−14.5~\mathrm{fb}^{-1} of e+e−e^+e^- annihilation data samples collected at the center-of-mass energies ranging from 4.600~GeV to 4.699~GeV with the BESIII detector at the BEPCII collider, a first study of the semileptonic decays Λc+→pK−e+νeΛ_c^+\rightarrow pK^-e^+ν_e, Λc+→Λ(1520)e+νeΛ_c^+\rightarrow Λ(1520) e^+ν_e and Λc+→Λ(1405)e+νeΛ_c^+\rightarrow Λ(1405) e^+ν_e is performed. The Λc+→pK−e+νeΛ_c^+\rightarrow pK^-e^+ν_e decay is observed with a significance of 8.2σ8.2σ and the branching fraction is measured to be B(Λc+→pK−e+νe)=(0.88±0.17stat.±0.07syst.)×10−3\mathcal{B}(Λ_c^+\rightarrow pK^- e^+ν_e)=(0.88\pm0.17_{\rm stat.}\pm0.07_{\rm syst.})\times 10^{-3}. We also report evidence of Λc+→Λ(1520)e+νeΛ_c^+\rightarrow Λ(1520)e^+ν_e and Λc+→Λ(1405)e+νeΛ_c^+\rightarrow Λ(1405)e^+ν_e with significances of 3.3σ3.3σ and 3.2σ3.2σ, respectively, and measure B(Λc+→Λ(1520)e+νe)=(1.02±0.52stat.±0.11syst.)×10−3\mathcal B(Λ^+_c\rightarrow Λ(1520)e^+ν_e)=(1.02\pm0.52_{\rm stat.}\pm0.11_{\rm syst.})\times10^{-3} and B(Λc+→Λ(1405)[→pK−]e+νe)=(0.42±0.19stat.±0.04syst.)×10−3\mathcal B(Λ^+_c\rightarrow Λ(1405)[\rightarrow pK^-]e^+ν_e)=(0.42\pm0.19_{\rm stat.}\pm0.04_{\rm syst.})\times10^{-3}. Combining these with the inclusive semileptonic Λc+Λ_c^+ branching fraction measured by BESIII, the relative fraction is determined to be [B(Λc+→pK−e+νe)/B(Λc+→Xe+νe)]=(2.1±0.4stat.±0.2syst.)%[\mathcal{B}(Λ_c^+\rightarrow pK^-e^+ν_e)/\mathcal{B}(Λ_c^+\rightarrow X e^+ν_e)]=(2.1\pm0.4_{\rm stat.}\pm0.2_{\rm syst.})\%, which provides a clear confirmation that semileptonic Λc+Λ_c^+ decays are not saturated by the Λℓ+νℓΛ\ell^+ν_{\ell} final state.

preprint2022arXiv

Formal guarantees for heuristic optimization algorithms used in machine learning

Recently, Stochastic Gradient Descent (SGD) and its variants have become the dominant methods in the large-scale optimization of machine learning (ML) problems. A variety of strategies have been proposed for tuning the step sizes, ranging from adaptive step sizes to heuristic methods to change the step size in each iteration. Also, momentum has been widely employed in ML tasks to accelerate the training process. Yet, there is a gap in our theoretical understanding of them. In this work, we start to close this gap by providing formal guarantees to a few heuristic optimization methods and proposing improved algorithms. First, we analyze a generalized version of the AdaGrad (Delayed AdaGrad) step sizes in both convex and non-convex settings, showing that these step sizes allow the algorithms to automatically adapt to the level of noise of the stochastic gradients. We show for the first time sufficient conditions for Delayed AdaGrad to achieve almost sure convergence of the gradients to zero. Moreover, we present a high probability analysis for Delayed AdaGrad and its momentum variant in the non-convex setting. Second, we analyze SGD with exponential and cosine step sizes, which are empirically successful but lack theoretical support. We provide the very first convergence guarantees for them in the smooth and non-convex setting, with and without the Polyak-Łojasiewicz (PL) condition. We also show their good property of adaptivity to noise under the PL condition. Third, we study the last iterate of momentum methods. We prove the first lower bound in the convex setting for the last iterate of SGD with constant momentum. Moreover, we investigate a class of Follow-The-Regularized-Leader-based momentum algorithms with increasing momentum and shrinking updates. We show that their last iterate has optimal convergence for unconstrained convex stochastic optimization problems.

preprint2022arXiv

Hallucinated Neural Radiance Fields in the Wild

Neural Radiance Fields (NeRF) has recently gained popularity for its impressive novel view synthesis ability. This paper studies the problem of hallucinated NeRF: i.e., recovering a realistic NeRF at a different time of day from a group of tourism images. Existing solutions adopt NeRF with a controllable appearance embedding to render novel views under various conditions, but they cannot render view-consistent images with an unseen appearance. To solve this problem, we present an end-to-end framework for constructing a hallucinated NeRF, dubbed as Ha-NeRF. Specifically, we propose an appearance hallucination module to handle time-varying appearances and transfer them to novel views. Considering the complex occlusions of tourism images, we introduce an anti-occlusion module to decompose the static subjects for visibility accurately. Experimental results on synthetic data and real tourism photo collections demonstrate that our method can hallucinate the desired appearances and render occlusion-free images from different views. The project and supplementary materials are available at https://rover-xingyu.github.io/Ha-NeRF/.

preprint2022arXiv

Measurement of e+e−→K+K−π0e^{+}e^{-} \to K^{+}K^{-}π^{0} cross section and observation of a resonant structure

Based on e+e−e^{+}e^{-} collision data collected by the BESIII detector at the BEPCII collider at center-of-mass energies from 2.000 to 3.080 GeV, a partial-wave analysis is performed for the process e+e−→K+K−π0e^{+}e^{-} \to K^{+}K^{-}π^{0}. The Born cross section of the process e+e−→K+K−π0e^{+}e^{-} \to K^{+}K^{-}π^{0} and its subprocesses e+e−→ϕπ0e^{+}e^{-} \to ϕπ^{0}, K∗(892)KK^{*}(892)K and K2∗(1430)KK^{*}_{2}(1430)K are measured. The results for e+e−→K+K−π0e^{+}e^{-} \to K^{+}K^{-}π^{0} and ϕπ0ϕπ^{0} are consistent with the BaBar measurements and with improved precision. By analyzing the cross section, of the subprocesses e+e−→e^{+}e^{-} \to K∗(892)KK^{*}(892)K and K2∗(1430)KK^{*}_{2}(1430)K, a structure with mass MRM_R = (2208 ±\pm 19 ±\pm 24) MeV/c2c^{2} and width ΓRΓ_R = (168 ±\pm 24 ±\pm 39) MeV is observed with a combined statistical significance of 7.6σσ. The measured resonance parameters suggest it can be identified as the ϕ(2170)ϕ(2170), thus the results provide valuable input to understand the internal nature of this state.

preprint2022arXiv

Measurement of ΛΛ baryon polarization in e+e−→ΛΛˉe^+e^-\rightarrowΛ\barΛ at s=3.773\sqrt{s} = 3.773 GeV

Using a data sample of ψ(3770)ψ(3770) events collected with the BESIII detector at BEPCII corresponding to an integrated luminosity of 2.9 fb−1^{-1}, we report a measurement of ΛΛ spin polarization in e+e−→ΛΛˉe^+e^-\rightarrowΛ\barΛ at s=3.773\sqrt{s} = 3.773 GeV. The significance of polarization is found to be 2σσ including the systematic uncertainty, which implies a zero phase between the transition amplitudes of the ΛΛˉΛ\barΛ helicity states. This phase can be interpreted in terms of psionic form factors, and is determined to be ΔΦΨΔΦ^Ψ = ΦEΨ−ΦMΨΦ^Ψ_{E} - Φ^Ψ_{M} = (71−46+66(71^{+66}_{-46} ±\pm 5)∘^{\circ}. Similarly, the ratio between the form factors is found to be RψR^ψ = ∣GEΨ/GMΨ∣|G^Ψ_{E}/G^Ψ_{M}| = 0.48−0.07+0.120.48^{+0.12}_{-0.07} ±\pm 0.04. The first uncertainties are statistical and the second systematic.

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

Measurement of the branching fraction and decay asymmetry of Λ→nγΛ\to nγ

The radiative hyperon decay Λ→nγΛ\to nγ is studied using (10087±44)×106(10087\pm44)\times 10^6 J/ψJ/ψ events collected with the BESIII detector operating at BEPCII. The absolute branching fraction of the decay Λ→nγΛ\to nγ is determined with a significance of 5.6σσ to be [0.832±0.038(stat.)±0.054(syst.)]×10−3[0.832\pm0.038(\rm stat.)\pm0.054(\rm syst.)]\times10^{-3}, which lies significantly below the current PDG value. By analyzing the joint angular distribution of the decay products, the first determination of the decay asymmetry αγα_γ is reported with a value of −0.16±0.10(stat.)±0.05(syst.)-0.16\pm0.10(\rm stat.)\pm0.05(\rm syst.).

preprint2022arXiv

Measurement of the branching fraction for ψ(3686)→ωKS0KS0ψ(3686)\to ωK^0_SK^0_S

Analyzing (448.1±2.9)×106(448.1\pm2.9)\times10^6 ψ(3686)ψ(3686) events collected with the BESIII detector at the BEPCII collider, the ψ(3686)→ωKS0KS0ψ(3686)\to ωK_{S}^{0}K_{S}^{0} decay is observed for the first time. The branching fraction for this decay is determined to be Bψ(3686)→ωKS0KS0\mathcal{B}_{ψ(3686)\to ωK_{S}^{0}K^{0}_{S}}=(7.04±0.39±0.36)(7.04\pm0.39\pm0.36)×10−5\times10^{-5}, where the first uncertainty is statistical and the second is systematic.

preprint2022arXiv

Measurement of the branching fraction of the doubly Cabibbo-suppressed decay D0→K+π−π0D^0\to K^+π^-π^0 and search for D0→K+π−π0π0D^0\to K^+π^-π^0π^0

Using 2.93 fb−12.93\,\rm fb^{-1} of e+e−e^+e^- collision data collected at a center-of-mass energy of 3.773\,GeV with the BESIII detector, we present a measurement of the branching fraction of the doubly Cabibbo-suppressed (DCS) decay D0→K+π−π0D^0\to K^+π^-π^0 and a search for the DCS decay D0→K+π−π0π0D^0\to K^+π^-π^0π^0. The branching fraction of D0→K+π−π0D^0\to K^+π^-π^0 is determined to be [3.13−0.56+0.60(stat)±0.09(syst)]×10−4[3.13^{+0.60}_{-0.56}({\rm stat}) \pm 0.09({\rm syst})] \times 10^{-4}. No signal is observed for D0→K+π−π0π0D^0\to K^+π^-π^0π^0 and an upper limit of 3.6×10−43.6 \times 10^{-4} is set on the branching fraction at the 90\% C.L. We combine these results with the world-average branching fractions of their counterpart Cabibbo-favored decays to determine the ratios of the doubly Cabibbo-suppressed over the Cabibbo-favored branching fractions, B(D0→K+π−π0)/B(D0→K−π+π0)=(0.22±0.04)%{\mathcal B}(D^0\to K^+π^-π^0)/{\mathcal B}(D^0\to K^-π^+π^0)=(0.22\pm 0.04)\%~and B(D0→K+π−π0π0)/B(D0→K−π+π0π0)<0.40%{\mathcal B}(D^0\to K^+π^-π^0π^0)/{\mathcal B}(D^0\to K^-π^+π^0π^0)<0.40\% at the 90\% C.L., which correspond to (0.75±0.14)tan⁡4θC(0.75\pm 0.14)\tan^{4} θ_C~and 1.37×tan⁡4θC1.37\times \tan^{4} θ_C, respectively, where θCθ_C is the Cabibbo angle.

preprint2022arXiv

Measurement of the Cross Section for e+e−→e^{+}e^{-}\to hadrons at Energies from 2.2324 to 3.6710 GeV

Based on electron-positron collision data collected with the BESIII detector operating at the Beijing Electron Positron Collider II storage rings, the value of R≡σ(e+e−→R\equivσ(e^{+}e^{-}\tohadrons)/σ(e+e−→μ+μ−)σ(e^{+}e^{-}\toμ^{+}μ^{-}) is measured at 14 center-of-mass energies from 2.2324 to 3.6710 GeV. The resulting uncertainties are less than 3.0%3.0\%, and are dominated by systematic uncertainties.

preprint2022arXiv

Measurement of the cross section of e+e−→ηπ+π−e^{+}e^{-}\toηπ^{+}π^{-} at center-of-mass energies from 3.872 GeV to 4.700 GeV

Using data samples with an integrated luminosity of 19 fb−1^{-1} at twenty-eight center-of-mass energies from 3.872 GeV to 4.700 GeV collected with the BESIII detector at the BEPCII electron--positron collider, the process e+e−→ηπ+π−e^{+}e^{-}\toηπ^{+}π^{-} and the intermediate process e+e−→ηρ0e^{+}e^{-}\toηρ^{0} are studied for the first time. The Born cross sections are measured. No significant resonance structure is observed in the cross section lineshape.

preprint2022arXiv

Measurement of the total and leptonic decay widths of the J/ψJ/ψ resonance with an energy scan method at BESIII

Using e+e−e^+e^- annihilation data sets collected with the BESIII detector, we measure the cross sections of the processes e+e−→e+e−e^+e^- \to e^+e^- and e+e−→μ+μ−e^+e^- \to μ^+μ^- at fifteen center-of-mass energy points in the vicinity of the J/ψJ/ψ resonance. By a simultaneous fit to the measured, center-of-mass energy dependent cross sections of the two processes, the combined quantities ΓeeΓee/ΓtotΓ_{ee} Γ_{ee} / Γ_{\rm tot} and ΓeeΓμμ/ΓtotΓ_{ee} Γ_{μμ} / Γ_{\rm tot} are determined to be (0.346±0.0090.346 \pm 0.009) and (0.335±0.0060.335 \pm 0.006) keV, respectively, where ΓeeΓ_{ee}, ΓμμΓ_{μμ}, and ΓtotΓ_{\rm tot} are the electronic, muonic, and total decay widths of the J/ψJ/ψ resonance, respectively. Using the resultant ΓeeΓμμ/ΓtotΓ_{ee} Γ_{μμ} / Γ_{\rm tot} and ΓeeΓee/ΓtotΓ_{ee} Γ_{ee} / Γ_{\rm tot}, the ratio Γee/ΓμμΓ_{ee} / Γ_{μμ} is calculated to be 1.031±0.0151.031 \pm 0.015, which is consistent with the expectation of lepton universality within about two standard deviations. Assuming lepton universality and using the branching fraction of the J/ψJ/ψ leptonic decay measured by BESIII in 2013, ΓtotΓ_{\rm tot} and ΓllΓ_{ll} are determined to be (93.0±2.193.0 \pm 2.1) and (5.56±0.115.56 \pm 0.11) keV, respectively, where ΓllΓ_{ll} is the average leptonic decay width of the J/ψJ/ψ resonance.

preprint2022arXiv

Measurements of Absolute Branching Fractions of D0→KL0ϕD^0\to K_L^0ϕ, KL0ηK_L^0η, KL0ωK_L^0ω, and KL0η′K_L^0η^{\prime}

We report the first measurements of the absolute branching fractions of D0→KL0ϕD^0\to K_L^0ϕ, D0→KL0ηD^0\to K_L^0η, D0→KL0ωD^0\to K_L^0ω, and D0→KL0η′D^0\to K_L^0η^{\prime}, obtained by analyzing 2.93 fb−12.93\,\rm fb^{-1} of e+e−e^+e^- collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. Taking the world averages of the branching fractions of D0→KS0ϕD^0\to K_S^0ϕ, D0→KS0ηD^0\to K_S^0η, D0→KS0ωD^0\to K_S^0ω, and D0→KS0η′D^0\to K_S^0η^{\prime}, the KS0K_S^0-KL0K_L^0 asymmetry R(D0)\mathcal{R}(D^0) in these decay modes are obtained. The CP asymmetries in these decays are also determined. No significant CPCP violation is observed.

preprint2022arXiv

Measurements of the absolute branching fractions of hadronic DD-meson decays involving kaons and pions

By analyzing an electron-positron collision data sample corresponding to an integrated luminosity of 2.93 fb−12.93\,\rm fb^{-1} taken at the center-of-mass energy of 3.773 GeV with the BESIII detector, we obtain for the first time the absolute branching fractions for seven D0D^0 and D+D^+ hadronic decay modes and search for the hadronic decay D0→KS0KS0π0D^0\to K^0_S K^0_Sπ^0 with much improved sensitivity. The results are B(D0→KS0π0π0π0)=(7.64±0.30±0.29)×10−3{\mathcal B}(D^0\to K^0_Sπ^0π^0π^0 )=( 7.64\pm 0.30\pm 0.29)\times 10^{-3}, B(D0→K−π+π0π0π0)=(9.54±0.30±0.31)×10−3{\mathcal B}(D^0\to K^-π^+π^0π^0π^0 )=( 9.54\pm 0.30\pm 0.31)\times 10^{-3}, B(D0→KS0π+π−π0π0)=(12.66±0.45±0.43)×10−3{\mathcal B}(D^0\to K^0_Sπ^+π^-π^0π^0)=(12.66\pm 0.45\pm 0.43)\times 10^{-3}, B(D+→KS0π+π0π0)=(29.04±0.62±0.87)×10−3{\mathcal B}(D^+\to K^0_Sπ^+π^0π^0 )=(29.04\pm 0.62\pm 0.87)\times 10^{-3}, B(D+→KS0π+π+π−π0)=(15.28±0.57±0.60)×10−3{\mathcal B}(D^+\to K^0_Sπ^+π^+π^-π^0)=(15.28\pm 0.57\pm 0.60)\times 10^{-3}, B(D+→KS0π+π0π0π0)=(5.54±0.44±0.32)×10−3{\mathcal B}(D^+\to K^0_Sπ^+π^0π^0π^0)=( 5.54\pm 0.44\pm 0.32)\times 10^{-3}, B(D+→K−π+π+π0π0)=(4.95±0.26±0.19)×10−3{\mathcal B}(D^+\to K^-π^+π^+π^0π^0 )=( 4.95\pm 0.26\pm 0.19)\times 10^{-3}, B(D0→KS0KS0π0)<1.57×10−4{\mathcal B}({D^0\to K^0_S K^0_Sπ^0}) < 1.57 \times 10^{-4} at the 90\% confidence level. Here the first uncertainties are statistical and the second ones systematic. The newly studied decays greatly enrich the knowledge of the D→KˉπππD\to \bar Kπππ and D→KˉππππD\to \bar Kππππ hadronic decays, and open a bridge to access more two-body hadronic DD decays containing scalar, vector, axial and tensor mesons in the charm sector.

preprint2022arXiv

Observation of a0(1710)+→KS0K+a_0(1710)^+ \to K_S^0K^+ in study of the Ds+→KS0K+π0D_s^+\to K_S^0K^+π^0 decay

Using e+e−e^+e^- annihilation data corresponding to an integrated luminosity of 6.32 fb−1^{-1} collected at center-of-mass energies between 4.178 GeV and 4.226 GeV with the BESIII detector, we perform the first amplitude analysis of the decay Ds+→KS0K+π0D_s^+\to K_S^0K^+π^0 and determine the relative branching fractions and phases for intermediate processes. We observe the a0(1710)+a_0(1710)^+, the isovector partner of the f0(1710)f_0(1710) and f0(1770)f_0(1770) mesons, in its decay to KS0K+K_S^0K^+ for the first time. In addition, we measure the ratio B(Ds+→Kˉ∗(892)0K+)B(Ds+→Kˉ0K∗(892)+)\frac{\mathcal{B}(D_{s}^{+} \to \bar{K}^{*}(892)^{0}K^{+})}{\mathcal{B}(D_{s}^{+} \to \bar{K}^{0}K^{*}(892)^{+})} to be 2.35−0.23stat.+0.42±0.10syst.2.35^{+0.42}_{-0.23\text{stat.}}\pm 0.10_{\rm syst.}. Finally, we provide a precision measurement of the absolute branching fraction B(Ds+→KS0K+π0)=(1.46±0.06stat.±0.05syst.)%\mathcal{B}(D_s^+\to K_S^0K^+π^0) = (1.46\pm 0.06_{\text{stat.}}\pm 0.05_{\text{syst.}})\%.

preprint2022arXiv

Observation of ηc(2S)→3(π+π−)η_c(2S) \to 3(π^+π^-) and measurements of χcJ→3(π+π−)χ_{cJ} \to 3(π^+π^-) in ψ(3686)ψ(3686) radiative transitions

The hadronic decay ηc(2S)→3(π+π−)η_c(2S) \to 3(π^+π^-) is observed with a statistical significance of 9.3 standard deviations using (448.1±2.9)×106(448.1\pm2.9)\times10^6 ψ(3686)ψ(3686) events collected by the BESIII detector at the BEPCII collider. The measured mass and width of ηc(2S)η_c(2S) are (3643.4±2.3(stat.)±4.4(syst.))(3643.4 \pm 2.3 (\rm stat.) \pm 4.4 (\rm syst.)) MeV/c2c^2 and (19.8±3.9(stat.)±3.1(syst.))(19.8 \pm 3.9 (\rm stat.) \pm 3.1 (\rm syst.)) MeV, respectively, which are consistent with the world average values within two standard deviations. The product branching fraction B[ψ(3686)→γηc(2S)]×B[ηc(2S)→3(π+π−)]\mathcal{B}[ψ(3686)\to γη_c(2S)]\times\mathcal{B}[η_c(2S)\to3(π^+π^-)] is measured to be (9.2±1.0(stat.)±0.9(syst.))×10−6(9.2 \pm 1.0 (\rm stat.) \pm 0.9 (\rm syst.))\times10^{-6}. Using B[ψ(3686)→γηc(2S)]=(7.0−2.5+3.4)×10−4\mathcal{B}[ψ(3686)\to γη_c(2S)]=(7.0^{+3.4}_{-2.5})\times10^{-4}, we obtain B[ηc(2S)→3(π+π−)]=(1.31±0.15(stat.)±0.13(syst.)(−0.47+0.64)(extr))×10−2\mathcal{B}[η_c(2S) \to 3(π^+π^-)] = (1.31 \pm 0.15 (\rm stat.) \pm 0.13 (\rm syst.)(^{+0.64}_{-0.47}) (\rm extr))\times10^{-2}, where the third uncertainty is from B[ψ(3686)→γηc(2S)]\mathcal{B}[ψ(3686) \to γη_c(2S)]. We also measure the χcJ→3(π+π−)χ_{cJ} \to 3(π^+π^-) (J=0,1,2J=0, 1, 2) decays via ψ(3686)→γχcJψ(3686) \to γχ_{cJ} transitions. The branching fractions are B[χc0→3(π+π−)]=(2.080±0.006(stat.)±0.068(syst.))×10−2\mathcal{B}[χ_{c0} \to 3(π^+π^-)] = (2.080\pm0.006 (\rm stat.)\pm0.068 (\rm syst.))\times10^{-2}, B[χc1→3(π+π−)]=(1.092±0.004(stat.)±0.035(syst.))×10−2\mathcal{B}[χ_{c1} \to 3(π^+π^-)] = (1.092\pm0.004 (\rm stat.)\pm0.035 (\rm syst.))\times10^{-2}, and B[χc2→3(π+π−)]=(1.565±0.005(stat.)±0.048(syst.))×10−2\mathcal{B}[χ_{c2} \to 3(π^+π^-)] = (1.565\pm0.005 (\rm stat.)\pm0.048 (\rm syst.))\times10^{-2}.

preprint2022arXiv

Observation of resonance structures in e+e−→π+π−ψ2(3823)e^+e^-\to π^+π^-ψ_2(3823) and mass measurement of ψ2(3823)ψ_2(3823)

Using a data sample corresponding to an integrated luminosity of 11.3 fb−1\rm fb^{-1} collected at center-of-mass energies from 4.234.23 to 4.704.70 GeV with the BESIII detector, we measure the product of the e+e−→π+π−ψ2(3823)e^+e^-\to π^+π^-ψ_2(3823) cross section and the branching fraction B[ψ2(3823)→γχc1]\mathcal{B}[ψ_2(3823)\to γχ_{c1}]. For the first time, resonance structure is observed in the cross section line shape of e+e−→π+π−ψ2(3823)e^+e^-\to π^+π^-ψ_2(3823) with significances exceeding 5σ5σ. A fit to data with two coherent Breit-Wigner resonances modeling the s\sqrt{s}-dependent cross section yields M(R1)=4406.9±17.2±4.5M(R_1)=4406.9\pm 17.2\pm 4.5 MeV/c2c^2, Γ(R1)=128.1±37.2±2.3Γ(R_1)=128.1\pm 37.2\pm 2.3 MeV, and M(R2)=4647.9±8.6±0.8M(R_2)=4647.9\pm 8.6\pm 0.8 MeV/c2c^2, Γ(R2)=33.1±18.6±4.1Γ(R_2)=33.1\pm 18.6\pm 4.1 MeV. Though weakly disfavored by the data, a single resonance with M(R)=4417.5±26.2±3.5M(R)=4417.5\pm26.2\pm3.5 MeV/c2c^2, Γ(R)=245±48±13Γ(R)=245\pm48\pm13 MeV is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ψ2(3823)ψ_2(3823) state is measured as (3823.12±0.43±0.13)(3823.12\pm 0.43\pm 0.13) MeV/c2c^2, which is the most precise measurement to date.

preprint2022arXiv

Observation of the double Dalitz decay η′→e+e−e+e−η'\to e^+e^-e^+e^-

Based on (10087±44)×106(10087 \pm 44)\times10^6 J/ψJ/ψ events collected with the BESIII detector at BEPCII, the double Dalitz decay η′→e+e−e+e−η'\to e^+e^-e^+e^- is observed for the first time via the J/ψ→γη′J/ψ\toγη' decay process. The significance is found to be 5.7σσ with systematic uncertainties taken into consideration. Its branching fraction is determined to be B(η′→e+e−e+e−)=(4.5±1.0(stat.)±0.5(sys.))×10−6\mathcal{B}(η'\to e^+ e^- e^+ e^-) =(4.5\pm1.0(\mathrm{stat.})\pm0.5(\mathrm{sys.})) \times 10^{-6}.

preprint2022arXiv

Observation of the electromagnetic Dalitz decay D∗0→D0e+e−D^{\ast 0}\to D^{0}e^{+}e^{-}

Based on 3.19 fb−1^{-1} of e+e−e^+e^- collision data accumulated at the center-of-mass energy 4.178 GeV with the BESIII detector operating at the BEPCII collider, the electromagnetic Dalitz decay D∗0→D0e+e−D^{\ast 0}\to D^{0}e^{+}e^{-} is observed for the first time with a statistical significance of 13.2σ13.2σ. The ratio of the branching fraction of D∗0→D0e+e−D^{\ast 0}\to D^{0}e^{+}e^{-} to that of D∗0→D0γD^{\ast 0}\to D^{0} γ is measured to be (11.08±0.76±0.49)×10−3(11.08\pm0.76\pm0.49)\times 10^{-3}. By using the world average value of the branching fraction of D∗0→D0γD^{\ast 0}\to D^{0} γ, the branching fraction of D∗0→D0e+e−D^{\ast 0}\to D^{0}e^{+}e^{-} is determined to be (3.91±0.27±0.17±0.10)×10−3(3.91\pm0.27\pm0.17\pm0.10)\times 10^{-3}, where the first uncertainty is statistical, the second systematic and the third external branching fractions.

preprint2022arXiv

Observation of the Singly Cabibbo-Suppressed Decay Λc+→nπ+Λ_{c}^{+} \to nπ^{+}

The singly Cabibbo-suppressed decay Λc+→nπ+Λ_{c}^{+} \to nπ^{+} is observed for the first time with a statistical significance of 7.3σ7.3σ by using 3.9 fb−1\mathrm{fb}^{-1} of e+e−e^{+}e^{-} collision data collected at center-of-mass energies between 4.612 and 4.699 GeV with the BESIII detector at BEPCII. The branching fraction of Λc+→nπ+Λ_{c}^{+} \to nπ^{+} is measured to be (6.6±1.2stat±0.4syst)×10−4(6.6\pm1.2_{\rm stat}\pm0.4_{\rm syst})\times 10^{-4}. By taking the upper limit of branching fractions of Λc+→pπ0Λ_{c}^{+} \to pπ^0 from the Belle experiment, the ratio of branching fractions between Λc+→nπ+Λ_{c}^{+} \to nπ^{+} and Λc+→pπ0Λ_{c}^{+} \to pπ^0 is calculated to be larger than 7.2 at the 90% confidence level, which disagrees with the current predictions of available phenomenological models. In addition, the branching fractions of the Cabibbo-favored decays Λc+→Λπ+Λ_{c}^{+} \to Λπ^{+} and Λc+→Σ0π+Λ_{c}^{+} \to Σ^{0}π^{+} are measured to be (1.31±0.08stat±0.05syst)×10−2(1.31\pm0.08_{\rm stat}\pm0.05_{\rm syst})\times 10^{-2} and (1.22±0.08stat±0.07syst)×10−2(1.22\pm0.08_{\rm stat}\pm0.07_{\rm syst})\times 10^{-2}, respectively, which are consistent with previous results.

preprint2022arXiv

Partial wave analysis of J/ψ→γη′η′J/ψ\to γη^{\prime} η^{\prime}

Using a sample of (10.09 ± 0.04)×109 J/ψ(10.09~\pm~0.04)\times10^{9} ~J/ψ events collected with the BESIII detector, a partial wave analysis of J/ψ→γη′η′J/ψ\toγη^{\prime}η^{\prime} is performed. The masses and widths of the observed resonances and their branching fractions are reported. The main contribution is from J/ψ→γf0(2020)J/ψ\rightarrowγf_0(2020) with f0(2020)→η′η′f_0(2020)\rightarrowη^{\prime}η^{\prime}, which is found with a significance of greater than 25σσ. The product branching fraction B(J/ψ→γf0(2020))⋅B(f0(2020)→η′η′){\cal B}\left(J/ψ\rightarrowγf_0(2020)\right)\cdot{\cal B}\left(f_0(2020)\rightarrowη^{\prime}η^{\prime}\right) is measured to be (2.63±0.06(stat.)−0.46+0.31(syst.))×10−4(2.63\pm0.06({\rm stat.})^{+0.31}_{-0.46}({\rm syst.}))\times10^{-4}.

preprint2022arXiv

Search for X(3872)→π0χc0X(3872)\toπ^0χ_{c0} and X(3872)→ππχc0X(3872)\toππχ_{c0} at BESIII

Using 9.9 fb−1^{-1} of e+e−e^+e^- collision data collected by the BESIII detector at center-of-mass energies between 4.15 and 4.30 GeV, we search for the processes e+e−→γX(3872)e^+e^-\toγX(3872) with X(3872)→π0χc0X(3872)\rightarrowπ^0χ_{c0} and X(3872)→ππχc0X(3872)\rightarrowππχ_{c0}. Depending on the fitting model, the statistical significance for X(3872)→π0χc0X(3872)\toπ^0χ_{c0} ranges from 1.3σσ to 2.8σσ. We set upper limits (at 90\% C.L.) of B(X(3872)→π0χc0)B(X(3872)→π+π−J/ψ)<3.6\frac{\mathcal{B}(X(3872)\rightarrowπ^0χ_{c0})}{\mathcal{B}(X(3872)\toπ^+π^-J/ψ)}<3.6, B(X(3872)→π+π−χc0)B(X(3872)→π+π−J/ψ)<0.68\frac{\mathcal{B}(X(3872)\rightarrowπ^+π^-χ_{c0})}{\mathcal{B}(X(3872)\toπ^+π^-J/ψ)}<0.68, and B(X(3872)→π0π0χc0)B(X(3872)→π+π−J/ψ)<1.7\frac{\mathcal{B}(X(3872)\rightarrowπ^0π^0χ_{c0})}{\mathcal{B}(X(3872)\toπ^+π^-J/ψ)}<1.7. Combined with the BESIII measurement of X(3872)→π0χc1X(3872)\toπ^0χ_{c1}, we also set an upper limit of B(X(3872)→π0χc0)B(X(3872)→π0χc1)<4.4\frac{\mathcal{B}(X(3872)\rightarrowπ^0χ_{c0})}{\mathcal{B}(X(3872)\toπ^0χ_{c1})}<4.4.

preprint2022arXiv

Search for baryon and lepton number violating decays D0→pˉe+D^{0}\to \bar{p}e^{+} and D0→pe−D^{0}\to pe^{-}

Using an electron-positron collision data sample corresponding to an integrated luminosity of 2.93~fb−1^{-1} collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we search for the baryon and lepton number violating decays D0→pˉe+D^{0}\to \bar{p}e^{+} and D0→pe−D^{0}\to pe^{-}. No obvious signals are found with the current statistics. The upper limits on the branching fractions for D0→pˉe+D^{0}\to \bar{p}e^{+} and D0→pe−D^{0}\to pe^{-} are set to be 1.2×10−61.2\times 10^{-6} and 2.2×10−62.2\times 10^{-6} at 90\% confidence level, respectively.

preprint2022arXiv

Search for baryon and lepton number violation decay D±→n(nˉ)e±D^{\pm}\to n(\bar{n})e^{\pm}

Using a data set of electron-positron collisions corresponding to an integrated luminosity of 2.93 fb−1{\rm 2.93~fb^{-1}} taken with the BESIII detector at a center-of-mass energy of 3.773 GeV, a search for the baryon (BB) and lepton (LL) number violating decays D±→n(nˉ)e±D^{\pm}\to n(\bar{n})e^{\pm} is performed. No signal is observed and the upper limits on the branching fractions at the 90%90\% confidence level are set to be 1.43×10−51.43\times10^{-5} for the decays D+(−)→nˉ(n)e+(−)D^{+(-)}\to \bar{n}(n)e^{+(-)} with Δ∣B−L∣=0Δ|B-L|=0, and 2.91×10−52.91\times10^{-5} for the decays D+(−)→n(nˉ)e+(−)D^{+(-)}\to n(\bar{n})e^{+(-)} with Δ∣B−L∣=2Δ|B-L|=2 , where Δ∣B−L∣Δ|B-L| denotes the change in the difference between baryon and lepton numbers.

preprint2022arXiv

Search for invisible decays of the ΛΛ baryon

A search for invisible decays of the ΛΛ baryon is carried out in the process J/ψ→ΛΛˉJ/ψ\toΛ\barΛ based on (1.0087±0.0044)×1010(1.0087\pm0.0044)\times10^{10} J/ψJ/ψ events collected with the BESIII detector located at the BEPCII storage ring. No signals are found for the invisible decays of ΛΛ baryon, and the upper limit of the branching fraction is determined to be 7.4×10−57.4 \times 10^{-5} at the 90% confidence level. This is the first search for invisible decays of baryons; such searches will play an important role in constraining dark sector models related to the baryon asymmetry.

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 D0→π0ννˉD^{0} \to π^{0} ν\barν

We present the first experimental search for the rare charm decay D0→π0ννˉD^{0} \to π^{0} ν\barν. It is based on an e+e−e^+e^- collision sample consisting of 10.6×10610.6\times10^{6} pairs of D0Dˉ0D^0\bar{D}^0 mesons collected by the BESIII detector at s\sqrt{s}=3.773 GeV, corresponding to an integrated luminosity of 2.93~fb−1^{-1}. A data-driven method is used to ensure the reliability of the background modeling. No significant D0→π0ννˉD^{0} \to π^{0} ν\barν signal is observed in data and an upper limit of the branching fraction is set to be 2.1×10−42.1\times 10^{-4} at the 90%\% confidence level. This is the first experimental constraint on charmed-hadron decays into dineutrino final states.

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 section measurements of the e+e−→D∗+D∗−e^+e^-\to D^{*+}D^{*-} and e+e−→D∗+D−e^+e^-\to D^{*+}D^{-} processes at center-of-mass energies from 4.085 to 4.600 GeV

The Born cross sections of the e+e−→D∗+D∗−e^+e^-\to D^{*+}D^{*-} and e+e−→D∗+D−e^+e^-\to D^{*+}D^{-} processes are measured using e+e−e^+e^- collision data collected with the BESIII experiment at center-of-mass energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15.7 fb−115.7~{\rm fb}^{-1}. The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.

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

Deep Sketch-guided Cartoon Video Inbetweening

We propose a novel framework to produce cartoon videos by fetching the color information from two input keyframes while following the animated motion guided by a user sketch. The key idea of the proposed approach is to estimate the dense cross-domain correspondence between the sketch and cartoon video frames, and employ a blending module with occlusion estimation to synthesize the middle frame guided by the sketch. After that, the input frames and the synthetic frame equipped with established correspondence are fed into an arbitrary-time frame interpolation pipeline to generate and refine additional inbetween frames. Finally, a module to preserve temporal consistency is employed. Compared to common frame interpolation methods, our approach can address frames with relatively large motion and also has the flexibility to enable users to control the generated video sequences by editing the sketch guidance. By explicitly considering the correspondence between frames and the sketch, we can achieve higher quality results than other image synthesis methods. Our results show that our system generalizes well to different movie frames, achieving better results than existing solutions.

preprint2021arXiv

Measurement of Branching Fractions of J/ψJ/ψ and ψ(3686)ψ(3686) decays to Σ+Σ^{+} and Σ‾−\overlineΣ^-

Using 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 detector, the branching fractions of J/ψJ/ψ and ψ(3686)ψ(3686) decays to Σ+Σ‾−Σ^{+}\overlineΣ^{-} are measured to be (10.61±0.04±0.36)×10−4(10.61 \pm 0.04 \pm 0.36) \times 10^{-4} and (2.52±0.04±0.09)×10−4(2.52 \pm 0.04 \pm 0.09) \times 10^{-4}, respectively. In addition, the ratio of B(ψ(3686)→Σ+Σ‾−)/B(J/ψ→Σ+Σ‾−)\mathcal{B}(ψ(3686) \rightarrow Σ^{+}\overlineΣ^{-})/\mathcal{B}(J/ψ\rightarrow Σ^{+}\overlineΣ^{-}) is determined to be (23.8±1.1)%(23.8 \pm 1.1)\% which violates the "12%12\% rule".

preprint2021arXiv

Observation of D0(+)→KS0π0(+)ωD^{0(+)}\to K^0_Sπ^{0(+)}ω and improved measurement of D0→K−π+ωD^0\to K^-π^+ω

By analyzing an e+e−e^+e^- annihilation data sample with an integrated luminosity of 2.93 fb−12.93\ \rm fb^{-1} taken at the center-of-mass energy of 3.773 GeV with the BESIII detector, we determine the absolute branching fractions of the hadronic decays D0→K−π+ωD^0\to K^-π^+ω, D0→KS0π0ωD^0\to K^0_Sπ^0ω, and D+→KS0π+ωD^+\to K^0_Sπ^+ω to be (3.392±0.044stat±0.085syst)%(3.392 \pm 0.044_{\rm stat} \pm 0.085_{\rm syst})\%, (0.848±0.046stat±0.031syst)%(0.848 \pm 0.046_{\rm stat} \pm 0.031_{\rm syst})\%, and (0.707±0.041stat±0.029syst)%(0.707 \pm 0.041_{\rm stat} \pm 0.029_{\rm syst})\%, respectively. The accuracy of the branching fraction measurement of the decay D0→K−π+ωD^0\to K^-π^+ω is improved by a factor of seven compared to the world average value. The D0→KS0π0ωD^{0}\to K^0_Sπ^{0}ω and D+→KS0π+ωD^{+}\to K^0_Sπ^{+}ω decays are observed for the first time.

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

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

A High Probability Analysis of Adaptive SGD with Momentum

Stochastic Gradient Descent (SGD) and its variants are the most used algorithms in machine learning applications. In particular, SGD with adaptive learning rates and momentum is the industry standard to train deep networks. Despite the enormous success of these methods, our theoretical understanding of these variants in the nonconvex setting is not complete, with most of the results only proving convergence in expectation and with strong assumptions on the stochastic gradients. In this paper, we present a high probability analysis for adaptive and momentum algorithms, under weak assumptions on the function, stochastic gradients, and learning rates. We use it to prove for the first time the convergence of the gradients to zero in high probability in the smooth nonconvex setting for Delayed AdaGrad with momentum.

preprint2020arXiv

GraphRQI: Classifying Driver Behaviors Using Graph Spectrums

We present a novel algorithm (GraphRQI) to identify driver behaviors from road-agent trajectories. Our approach assumes that the road-agents exhibit a range of driving traits, such as aggressive or conservative driving. Moreover, these traits affect the trajectories of nearby road-agents as well as the interactions between road-agents. We represent these inter-agent interactions using unweighted and undirected traffic graphs. Our algorithm classifies the driver behavior using a supervised learning algorithm by reducing the computation to the spectral analysis of the traffic graph. Moreover, we present a novel eigenvalue algorithm to compute the spectrum efficiently. We provide theoretical guarantees for the running time complexity of our eigenvalue algorithm and show that it is faster than previous methods by 2 times. We evaluate the classification accuracy of our approach on traffic videos and autonomous driving datasets corresponding to urban traffic. In practice, GraphRQI achieves an accuracy improvement of up to 25% over prior driver behavior classification algorithms. We also use our classification algorithm to predict the future trajectories of road-agents.

preprint2016arXiv

Machine Learned Resume-Job Matching Solution

Job search through online matching engines nowadays are very prominent and beneficial to both job seekers and employers. But the solutions of traditional engines without understanding the semantic meanings of different resumes have not kept pace with the incredible changes in machine learning techniques and computing capability. These solutions are usually driven by manual rules and predefined weights of keywords which lead to an inefficient and frustrating search experience. To this end, we present a machine learned solution with rich features and deep learning methods. Our solution includes three configurable modules that can be plugged with little restrictions. Namely, unsupervised feature extraction, base classifiers training and ensemble method learning. In our solution, rather than using manual rules, machine learned methods to automatically detect the semantic similarity of positions are proposed. Then four competitive "shallow" estimators and "deep" estimators are selected. Finally, ensemble methods to bag these estimators and aggregate their individual predictions to form a final prediction are verified. Experimental results of over 47 thousand resumes show that our solution can significantly improve the predication precision current position, salary, educational background and company scale.

preprint2016arXiv

Quantum Laplacian Eigenmap

Laplacian eigenmap algorithm is a typical nonlinear model for dimensionality reduction in classical machine learning. We propose an efficient quantum Laplacian eigenmap algorithm to exponentially speed up the original counterparts. In our work, we demonstrate that the Hermitian chain product proposed in quantum linear discriminant analysis (arXiv:1510.00113,2015) can be applied to implement quantum Laplacian eigenmap algorithm. While classical Laplacian eigenmap algorithm requires polynomial time to solve the eigenvector problem, our algorithm is able to exponentially speed up nonlinear dimensionality reduction.

preprint2015arXiv

An Empirical Study on Sentiment Classification of Chinese Review using Word Embedding

In this article, how word embeddings can be used as features in Chinese sentiment classification is presented. Firstly, a Chinese opinion corpus is built with a million comments from hotel review websites. Then the word embeddings which represent each comment are used as input in different machine learning methods for sentiment classification, including SVM, Logistic Regression, Convolutional Neural Network (CNN) and ensemble methods. These methods get better performance compared with N-gram models using Naive Bayes (NB) and Maximum Entropy (ME). Finally, a combination of machine learning methods is proposed which presents an outstanding performance in precision, recall and F1 score. After selecting the most useful methods to construct the combinational model and testing over the corpus, the final F1 score is 0.920.

preprint2013arXiv

Description of coupling in the category of transitive Lie algebroids

In our previous paper (arXiv:1306.5449) we have given a sufficient and necessary condition when the coupling between Lie algebra bundle (LAB) and the tangent bundle exists in the sense of Mackenzie (\cite{Mck-2005}, Definition 7.2.2) for the theory of transitive Lie algebroids. Namely we have defined a new topology on the group $\Aut(\rg)$ of all automorphisms of the Lie algebra $\rg$, say $\Aut(\rg)^δ$, and show that tangent bundle TMTM can be coupled with the Lie algebra bundle LL if and only if the Lie algebra bundle L admits a local trivial structure with structural group endowed with such new topology. But the question how many couplings exist under these conditions still remains open. Here we make the result more accurate and prove that there is a one-to-one correspondence between the family Coup(L)Coup(L) of all coupling of the Lie algebra bundle LL with fixed finite dimensional Lie algebra $\rg$ as the fiber and the structural group $\Aut(\rg)$ of all automorphisms of Lie algebra $\rg$ and the tangent bundle TMTM and the family LABδ(L)LAB^δ(L) of equivalent classes of local trivial structures with structural group $\Aut(\rg)$ endowed with new topology $\Aut(\rg)^δ$. This result gives a way for geometric construction of the classifying space for transitive Lie algebroids with fixed structural finite dimensiaonal Lie algebra $\rg$. Hence we can clarify a categorical description of the characteristic classes for transitive Lie algebroids and a comparison with that by J. Kubarski.

preprint2013arXiv

The Existence of Coupling in the Category of Transitive Lie Algebroid

The coupling of the tangent bundle TMTM with the Lie algebra bundle LL (K.Mackenzie,2005, Definition 7.2.2) plays the crucial role in the classification of the transitive Lie algebroids for Lie algebra bundle LL with fixed finite dimensional Lie algebra $\rg$ as a fiber of LL. Here we give a necessary and sufficient condition for existence such a coupling. Namely we define a new topology on the group $\Aut(\rg)$ of all automorphisms of Lie algebra $\rg$ and show that tangent bundle TMTM can be coupled with the Lie algebra bundle LL if and only if the Lie algebra bundle L admits a local trivial structure with structural group endowed with such new topology. The second version of the article is different from the first because of the improvement of the text by invaluable efforts of professor J.Stasheff, to whom we submit our sincere gratitude.

preprint2012arXiv

Comparison of categorical characteristic classes of transitive Lie algebroid with Chern-Weil homomorphism

Transitive Lie algebroids have specific properties that allow to look at the transitive Lie algebroid as an element of the object of a homotopy functor. Roughly speaking each transitive Lie algebroids can be described as a vector bundle over the tangent bundle of the manifold which is endowed with additional structures. Therefore transitive Lie algebroids admits a construction of inverse image generated by a smooth mapping of smooth manifolds. Due to to K.Mackenzie (2005) the construction can be managed as a homotopy functor $\mathcal{TLA}_{\rg}$ from category of smooth manifolds to the transitive Lie algebroids. The functor $\mathcal{TLA}_{\rg}$ associates with each smooth manifold MM the set $\mathcal{TLA}_{\rg}(M)$ of all transitive algebroids with fixed structural finite dimensional Lie algebra $\rg$. Hence one can construct a classifying space $\cB_{\rg}$ such that the family of all transitive Lie algebroids with fixed Lie algebra $\rg$ over the manifold MM has one-to-one correspondence with the family of homotopy classes of continuous maps $[M,\cB_{\rg}]$: $\mathcal{TLA}_{\rg}(M)\approx [M,\cB_{\rg}].$ It allows to describe characteristic classes of transitive Lie algebroids from the point of view a natural transformation of functors similar to the classical abstract characteristic classes for vector bundles and to compare them with that derived from the Chern-Weil homomorphism by J.Kubarski. As a matter of fact we show that the Chern-Weil homomorphism does not cover all characteristic classes from categorical point of view.

preprint2010arXiv

Process Algebra as Abstract Data Types

In this paper we introduced an algebraic semantics for process algebra in form of abstract data types. For that purpose, we developed a particular type of algebra, the seed algebra, which describes exactly the behavior of a process within a labeled transition system. We have shown the possibility of characterizing the bisimulation of two processes with the isomorphism of their corresponding seed algebras. We pointed out that the traditional concept of isomorphism of algebra does not apply here, because there is even no one-one correspondence between the elements of two seed algebras. The lack of this one-one correspondence comes from the non-deterministic choice of transitions of a process. We introduce a technique of hidden operations to mask unwanted details of elements of a seed algebra, which only reflect non-determinism or other implicit control mechanism of process transition. Elements of a seed algebra are considered as indistinguishable if they show the same behavior after these unwanted details are masked. Each class of indistinguishable elements is called a non-hidden closure. We proved that bisimulation of two processes is equivalent to isomorphism of non-hidden closures of two seed algebras representing these two processes. We call this kind of isomorphism a deep isomorphism. We get different models of seed algebra by specifying different axiom systems for the same signature. Each model corresponds to a different kind of bisimulation. By proving the relations between these models we also established relations between 10 different bisimulations, which form a acyclic directed graph.

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