arXiv subjects

Lu Guo

Publications and source records attributed to Lu Guo.

At least 19 recordsLinked to original sources

arXiv2026

Microscopic study of quasifission dynamics in hot fusion reactions for synthesizing superheavy nuclei with Z = 112-120

In the synthesis of superheavy element (SHE) via heavy-ion fusion reactions, quasifission is one of the major factors hindering superheavy nuclei (SHN) formation and the mechanism behind this process is intricate. We investigate dynamics of quasifission in hot fusion reactions synthesizing SHN with Z = 112-120 using microscopic time-dependent Hartree-Fock theory in a total of 18 reactions. Remarkably, the nucleon numbers of heavy fragments distribute closely around certain quantum shells in these reactions, highlighting the crucial role of shell effects in fragment formation. In the reactions with 48Ca, 45Sc, 50Ti and 51V projectiles, the formation of heavy fragment is dominantly driven by the double spherical shells of 208Pb. In contrast, the influence of the double octupole deformed shells at Z = 88 and N = 136 is more pronounced in 54Cr-induced reactions, resulting in a tendency of producing pear-shaped 224Ra heavy fragment. Moreover, in the reaction with a heavier projectile, the colliding system tends to undergo a more rapid quasifission. This may be responsible for significantly reduced fusion probability and synthesis cross section observed in the reactions with projectiles heavier than 48Ca. These results elucidate quasifission mechanisms behind the reactions for synthesizing new SHEs Z = 119 and Z = 120.

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arXiv2026

Hyperon-Nucleon Spectrometer

Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $\Lambda$ polarization puzzle, in which $\Lambda$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ($pp$), proton-nucleus ($pA$), and nucleus-nucleus ($AA$) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $pA$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

physics.ins-det↗

arXiv2026

Impact of octupole correlation on the inverse quasifission in ${}^{160}\text{Gd}+{}^{186}\text{W}$ collisions

Multinucleon transfer (MNT) reactions offer a promising pathway to synthesize neutron-rich heavy nuclei, but the mechanism of inverse quasifission, as a key reaction channel of MNT, still remains not well understood. We employ time-dependent Hartree-Fock theory to investigate the reaction mechanism, especially the role of the octupole deformed shell in the MNT reaction of ${}^{160}\text{Gd}+{}^{186}\text{W}$. The results show that inverse quasifission occurs when the deformed projectile and target collide in near tip-tip and tip-side orientations, which favors production of neutron-rich transtarget nuclei. Interestingly, the distributions and single-particle spectra of primary products reveal that the $N=88$ octupole deformed shell in light fragments dominates inverse quasifission instead of the spherical shells of $^{208}\text{Pb}$ at a center-of-mass energy of $502.6~\text{MeV}$, thus explaining the experimental observation that the yields of the transtarget products are enhanced in the Au region. Further exploration finds that quantum shell effects in inverse quasifission exhibit energy dependence. These results demonstrate that the octupole deformed shell plays a crucial role in the inverse quasifission dynamics, significantly advancing the understanding of the MNT reaction mechanism.

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arXiv2026

Microscopic Investigation of Fusion and Quasifission Dynamics

We introduce the application of Time-Dependent Hartree-Fock (TDHF) theory to two key aspects of heavy-ion reaction dynamics for producing superheavy elements: fusion and quasi-fission (QF). For fusion reactions $^{48}$Ca+$^{238}$U, the capture cross sections, fusion probabilities, and evaporation-residue cross sections are calculated using the inputs from TDHF simulations, and the results are found to be in reasonable agreement with available experimental data. For the QF process of $^{48}$Ca+$^{249}$Bk, we show the distribution of the fragments and investigate the impact of the tensor force, significantly enhancing the role of spherical shell effects.

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arXiv2026

Microscopic quasifission dynamics of the ${}^{54}\text{Cr}+{}^{243}\text{Am}$ reaction

Synthesizing superheavy elements (SHEs) like $Z=119$ is severely hindered by the dominant quasifission (QF) channel, which prevents compound nucleus formation. Understanding QF dynamics is thus essential for future experiments. We investigate the QF mechanisms in the $^{54}\text{Cr}+^{243}\text{Am}$ reaction, a key candidate system for SHE 119, emphasizing the roles of projectile orientation and incident energy. Calculations are performed using the fully microscopic time-dependent Hartree-Fock theory based on the Skyrme energy density functional. We conduct systematic simulations covering a broad set of initial orientations of the deformed $^{54}\text{Cr}$ and $^{243}\text{Am}$ nuclei, alongside a finely spaced range of incident energies extending from below to well above the Coulomb barrier. Our fixed-energy results show that projectile side collisions are governed by shell effects driving heavy and light fragments toward spherical $Z=82$ and deformed $N=52\text{--}56$ closures, respectively, whereas tip collisions exhibit weaker shell influence. These shell-dominated reactions are characterized by shorter interaction times, attributed to the enhanced rigidity of shell-stabilized fragments accelerating neck rupture. The energy dependence reveals a complex evolution where the system transitions from an octupole-stabilized regime ($Z \approx 88$) to a spherical shell-driven regime, with specific energy windows exhibiting suppressed shell influence. Our study demonstrates that the manifestation of shell effects in QF is a dynamical outcome sensitively dependent on both collision geometry and incident energy. Systematically probing this energy sensitivity is crucial for identifying optimal incident energies where the QF process exhibits suppressed shell influence, thereby potentially enhancing the fusion probability and improving the prospects for synthesizing new SHEs.

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arXiv2025

OpComm: A Reinforcement Learning Framework for Adaptive Buffer Control in Warehouse Volume Forecasting

Accurate forecasting of package volumes at delivery stations is critical for last-mile logistics, where errors lead to inefficient resource allocation, higher costs, and delivery delays. We propose OpComm, a forecasting and decision-support framework that combines supervised learning with reinforcement learning-based buffer control and a generative AI-driven communication module. A LightGBM regression model generates station-level demand forecasts, which serve as context for a Proximal Policy Optimization (PPO) agent that selects buffer levels from a discrete action set. The reward function penalizes under-buffering more heavily than over-buffering, reflecting real-world trade-offs between unmet demand risks and resource inefficiency. Station outcomes are fed back through a Monte Carlo update mechanism, enabling continual policy adaptation. To enhance interpretability, a generative AI layer produces executive-level summaries and scenario analyses grounded in SHAP-based feature attributions. Across 400+ stations, OpComm reduced Weighted Absolute Percentage Error (WAPE) by 21.65% compared to manual forecasts, while lowering under-buffering incidents and improving transparency for decision-makers. This work shows how contextual reinforcement learning, coupled with predictive modeling, can address operational forecasting challenges and bridge statistical rigor with practical decision-making in high-stakes logistics environments.

cs.LG↗

arXiv2025

Node-Level Financial Optimization in Demand Forecasting Through Dynamic Cost Asymmetry and Feedback Mechanism

This work introduces a methodology to adjust forecasts based on node-specific cost function asymmetry. The proposed model generates savings by dynamically incorporating the cost asymmetry into the forecasting error probability distribution to favor the least expensive scenario. Savings are calculated and a self-regulation mechanism modulates the adjustments magnitude based on the observed savings, enabling the model to adapt to station-specific conditions and unmodeled factors such as calibration errors or shifting macroeconomic dynamics. Finally, empirical results demonstrate the model's ability to achieve \$5.1M annual savings.

cs.LG↗

arXiv2025

Vidi2.5: Large Multimodal Models for Video Understanding and Creation

Video has emerged as the primary medium for communication and creativity on the Internet, driving strong demand for scalable, high-quality video production. Vidi models continue to evolve toward next-generation video creation and have achieved state-of-the-art performance in multimodal temporal retrieval (TR). In its second release, Vidi2 advances video understanding with fine-grained spatio-temporal grounding (STG) and extends its capability to video question answering (Video QA), enabling comprehensive multimodal reasoning. Given a text query, Vidi2 can identify not only the corresponding timestamps but also the bounding boxes of target objects within the output time ranges. To enable comprehensive evaluation of STG, we introduce a new benchmark, VUE-STG, which offers critical improvements over existing STG datasets. In addition, we upgrade the previous VUE-TR benchmark to VUE-TR-V2, achieving a more balanced duration and query distribution. Remarkably, the Vidi2 model substantially outperforms leading proprietary systems, such as Gemini 3 Pro Preview and GPT-5, on both VUE-TR-V2 and VUE-STG, while achieving competitive results with popular open-source models with similar scale on video QA benchmarks. The latest Vidi2.5 offers significantly stronger STG capability and slightly better TR and Video QA performance over Vidi2. This update also introduces a Vidi2.5-Think model to handle plot understanding with complex plot reasoning. To comprehensively evaluate the performance of plot understanding, we propose VUE-PLOT benchmark with two tracks, Character and Reasoning. Notably, Vidi2.5-Think outperforms Gemini 3 Pro Preview on fine-grained character understanding with comparable performance on complex plot reasoning. Furthermore, we demonstrate the effectiveness of Vidi2.5 on a challenging real-world application, video editing planning.

cs.CV↗

arXiv2025

RAD: Retrieval High-quality Demonstrations to Enhance Decision-making

Offline reinforcement learning (RL) learns policies from fixed datasets, thereby avoiding costly or unsafe environment interactions. However, its reliance on finite static datasets inherently restricts the ability to generalize beyond the training distribution. Prior solutions based on synthetic data augmentation often fail to generalize to unseen scenarios in the (augmented) dataset. To address these challenges, we propose Retrieval High-quAlity Demonstrations (RAD) for decision-making, which innovatively introduces a retrieval mechanism into offline RL. Specifically, RAD retrieves high-return and reachable states from the offline dataset as target states, and leverages a generative model to generate sub-trajectories conditioned on these targets for planning. Since the targets are high-return states, once the agent reaches such a target, it can continue to obtain high returns by following the associated high-return actions, thereby improving policy generalization. Extensive experiments confirm that RAD achieves competitive or superior performance compared to baselines across diverse benchmarks, validating its effectiveness. Our code is available at https://github.com/LeahGL/RAD.

cs.AI↗

arXiv2025

Vidi: Large Multimodal Models for Video Understanding and Editing

Humans naturally share information with those they are connected to, and video has become one of the dominant mediums for communication and expression on the Internet. To support the creation of high-quality large-scale video content, a modern pipeline requires a comprehensive understanding of both the raw input materials (e.g., the unedited footage captured by cameras) and the editing components (e.g., visual effects). In video editing scenarios, models must process multiple modalities (e.g., vision, audio, text) with strong background knowledge and handle flexible input lengths (e.g., hour-long raw videos), which poses significant challenges for traditional models. In this report, we introduce Vidi, a family of Large Multimodal Models (LMMs) for a wide range of video understand editing scenarios. The first release focuses on temporal retrieval, i.e., identifying the time ranges within the input videos corresponding to a given text query, which plays a critical role in intelligent editing. The model is capable of processing hour-long videos with strong temporal understanding capability, e.g., retrieve time ranges for certain queries. To support a comprehensive evaluation in real-world scenarios, we also present the VUE-TR benchmark, which introduces five key advancements. 1) Video duration: significantly longer than videos of existing temporal retrival datasets, 2) Audio support: includes audio-based queries, 3) Query format: diverse query lengths/formats, 4) Annotation quality: ground-truth time ranges are manually annotated. 5) Evaluation metric: a refined IoU metric to support evaluation over multiple time ranges. Remarkably, Vidi significantly outperforms leading proprietary models, e.g., GPT-4o and Gemini, on the temporal retrieval task, indicating its superiority in video editing scenarios.

cs.CV↗

arXiv2025

Simultaneous optical power delivery and distributed sensing through cross-band wavelength multiplexing over fiber link

Optical fibers offer significant advantages in both power delivery and distributed sensing. In remote areas where stable power supply is not easy to access, the distributed optical fiber sensing (DOFS) which offers long distance monitoring capability and the power-over-fiber (PoF) which can provide energy for connected electronics or other sensors are highly desired simultaneously. In this letter, the PoF-DOFS hybrid system is proposed and experimentally verified for the first time. By multiplexing the power channel and sensing channel with large wavelength separation, the cross-talk is greatly reduced. The results show that the Brillouin frequency shift under different temperature in the Brillouin optical time domain reflectometry remains unaffected by the high-power transmission background and the power delivery efficiency up to ~66% can be achieved over 1.3 km fiber link. This work paves the way for further research on PoF-DOFS hybrid system and gives a valuable solution for creating multi-parameter, multi-scale sensing network without the need for local power source.

physics.optics↗

arXiv2025

Power-over-fiber and distributed acoustic sensing hybridization in single fiber channel

The efficient and independent operation of power-over-fiber (PoF) and distributed acoustic sensing (DAS) has been demonstrated using standard single-mode fiber (SSMF). A transmission optical power efficiency (OPTE) of 6.67% was achieved over an 11.8 km fiber link, supporting both power delivery and distributed optical fiber sensing (DOFS). To minimize cross-talk, the system separates the power and sensing channels by a 40 THz bandwidth. In the experiment, the power and sensing light wavelengths are 1064 nm (continuous) and 1550 nm (pulsed), respectively. As the transmitted optical power increased from 0 W to 2.13 W, the DAS system successfully localized vibration sources and reconstructed phase information, confirming its ability to operate under high optical power. The reported scheme verifies the possibility of constructing the sensing-energy hybrid network based on conventional optical fiber with the advantages of flexibility and low cost.

physics.optics↗

arXiv2024

Impact of tensor forces on quasifission product yield distributions

We employ the microscopic time-dependent Hartree-Fock (TDHF) theory to study the 48Ca+249Bk and 48Ti+238U systems, taking into account the dependence on orientation for deformed nuclei and full range of impact parameters. By analyzing fragment distributions of neutron and proton numbers, we assess the influence of different isoscalar and isovector tensor coupling constants of the effective nucleon-nucleon interaction. The quasifission yield distributions of 48Ca + 249Bk collision system utilizing SLy5t and T31 parametrizations exhibit more pronounced spherical shell effects compared to those using SLy5, T44 and T62 sets. Furthermore, within each parametrization group, the distributions for SLy5t and T31 are closely aligned, as are those for SLy5, T44, and T62. Similarly, the yield distributions for the 48Ti + 238U system using SLy5t and T31 also reflect the more pronounced spherical shell effects relative to SLy5 and T62, while the charge distribution shows much better agreement with experimental results for the SLy5t and T62 parametrizations compared to SLy5 and T31. The yield distributions for the 48Ca+249Bk and 48Ti+238U systems, when compared across the SLy5, SLy5t, T31, T44, and T62 parametrizations, indicate that the influence of tensor forces on quasifission fragments is reflected in the prominence of shell effects. This influence appears to be sensitive only in specific regions within the isoscalar and isovector coupling constant parameter space. In the 48Ti + 238U system, the prominence of shell effects is manifested not only through shifts in peak positions but also through narrower yield distributions.

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arXiv2024

Fission fragment distributions within time-dependent density functional theory

A notable issue, the proper description of mass and charge distributions of fission fragments within nonadiabatic descriptions of fission dynamics, is investigated by performing double particle number projection on the outcomes of time-dependent Hartree-Fock (TDHF) simulation. The induced fission process of the benchmark nucleus 240Pu is studied. In the three-dimensional Cartesian coordinate without any symmetry restrictions, we get the static fission pathway from the two-dimensional potential energy surface, and then the fission dynamics from saddle to scission point are obtained using TDHF. We show that the charge numbers of primary heavy fragments from TDHF simulation strongly depend on the deformations of initial configurations via the two asymmetric fission channels, which can be distinguished according to the dynamical fission trajectories. The charge distribution of fission fragments is well reproduced using the double particle number projection technique. After applying the Gaussian kernel estimation based on the distribution from the double particle number projection technique, the mass distribution is also consistent with the experimental results. Besides, the results of the total kinetic energy of fission fragments are reasonably consistent with the experiments.

nucl-th↗

arXiv2024

Role of the tensor force in induced fission of 240Pu

Results: We find that the tensor force affects the height of fission barriers and the double-humped structure of fission path of 240Pu. On the PES, the fission valley becomes larger in the (Q20, Q30) plane, and the triaxial deformation is suppressed around the outer barrier after considering the tensor force. Incorporating the tensor force into the dynamical process enhances the difference in shape evolution between two asymmetric channels. More interestingly, the charge distribution from TDHF with double PNP calculations shows a strong odd-even effect after including the tensor force. In addition, the total mass and charge distributions of fission fragments show a slight shift towards larger asymmetry and are more consistent with the experiments when tensor components are included. We also find that the tensor force enhances energy gaps of the deformed shells for heavy fragments. Moreover, the TKEs of fragments are in accord with the experiments, and after incorporating the tensor force, we observe a higher concentration of the calculated TKEs for heavy fragments at Z = 52 and Z = 56. Conclusions: The tensor force plays a role in both static and dynamical processes in nuclear fission, improving the accuracy of theoretical descriptions within the current framework. Our calculations have shown that the fission-barrier height with SLy5t is closer to the empirical value than that of SLy5. Additionally, the inclusion of the tensor force not only manifests the odd-even effect in charge distribution but also improves the description of total mass and charge distributions.

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arXiv2022

Production of proton-rich nuclei in the vicinity of 100Sn via multinucleon transfer reactions

The production of new proton-rich nuclei in the vicinity of 100Sn is investigated via multinucleon transfer reactions within the framework of microscopic time-dependent Hartree-Fock (TDHF) and statistical model GEMINI++. The TDHF+GEMINI method has demonstrated the reliable description in the multinucleon transfer dynamics and the agreement between theoretical results and experimental data is quite satisfactory in the observed transfer reactions. We reveal the production cross sections of proton-rich nuclei in 100Sn region via multinucleon transfer reactions to be several orders of magnitude higher than those measured via fusion-evaporation and projectile fragmentation experiments. About 19 new proton-rich isotopes with cross sections of larger than 1 nb are predicted to be produced in multinucleon transfer reaction of 58Ni with 112Sn. The reaction mechanisms are discussed to lead the experimental production of these previously unreported nuclei. Multinucleon transfer reactions provide a fascinating possibility to reach the proton drip-line in 100Sn region and beyond.

nucl-th↗

arXiv2022

Impact of tensor force on quantum shell effects in quasifission reactions

Quantum shell effects drive many aspects of many-body quantal systems and their interactions. Among these are the quasifission reactions that impede the formation of a compound nucleus in superheavy element (SHE) searches. Fragment production in quasifission is influenced by shell effects as a nontrivial manifestation of microscopic dynamics hindering the full equilibration of the composite system to form the compound nucleus. In this Letter, we use the microscopic time-dependent Hartree-Fock (TDHF) theory to study 48Ca+249Bk collisions to investigate the influence of the tensor component of the effective nucleon-nucleon interaction. The results show that the inclusion of the tensor force causes the spherical shell effect to become more prominent, particularly for the neutron number yield whose peak is exactly at magic number N = 126. This suggests that the tensor force plays a compelling role in the evolution of dynamical shell effects in nuclear reactions, influencing the competition between spherical and deformed shell gaps.

nucl-th↗

arXiv2022

Microscopic study on fusion reactions $^{40,48}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ and the effect of tensor force

We provide a microscopic description of the fusion reactions between $^{40,48}$Ca and $^{78}$Ni. The internuclear potentials are obtained using the density-constrained (DC) time-dependent Hartree-Fock (TDHF) approach and fusion cross sections are calculated via the incoming wave boundary condition method. By performing DC-TDHF calculations at several selected incident energies, the internuclear potentials for both systems are obtained and the energy-dependence of fusion barrier are revealed. The influence of tensor force on internuclear potentials of $^{48}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ is more obvious than those of $^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$. By comparing the calculated fusion cross sections between $^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ and $^{48}\mathrm{Ca}+{}^{78}\mathrm{Ni}$, an interesting enhancement of sub-barrier fusion cross sections for the former system is found, which can be explained by the narrow width of internuclear potential for $^{40}\mathrm{Ca}+{}^{78}\mathrm{Ni}$ while the barrier heights and positions are very close to each other. The tensor force suppresses the sub-barrier fusion cross sections of both two systems.

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