arXiv subjects

Chuan Liu

Publications and source records attributed to Chuan Liu.

At least 19 recordsLinked to original sources

arXiv2026

TrustAgent-RFF: Agentic Diagnostic Planning for Reliable RF Fingerprinting under Domain Shift

Radio frequency fingerprinting (RFF) models can achieve accuracy under source domain conditions but become unreliable when the receiver, distance, collection day, or environment changes. Incorrect predictions in unseen domains may receive high softmax confidence, making confidence thresholding insufficient for trustworthy deployment. We propose TrustAgent-RFF, a prediction level reliability framework for RFF that operates with a frozen in-phase and quadrature (I/Q) classifier without target domain labels. For each device prediction, the framework acquires radio frequency evidence: counterfactual stability, prototype consistency, acquisition domain similarity, and signal quality. A source calibrated trust estimator combines these diagnostics with classifier confidence, prediction margin, and evidence availability indicators. Source derived lower tail penalties and cross module interactions reduce trust when diagnostic signals indicate weak support. A large language model (LLM) based planner adaptively selects the next diagnostic action based on evidence, trust state, action costs, and remaining budget. A deterministic source calibrated decision layer updates the prediction state as Accept, Reject, or Defer. Experiments across five RFF datasets and classifier backbones reveal an average source to target accuracy drop of 38.7% and show that many incorrect target domain predictions remain highly confident.

cs.LG↗

arXiv2026

SPLASH: Switching Parallel Layouts of Attention with Seamless Handoff for LLM Serving

No single way of parallelizing attention serves large language models well under all loads. Low concurrency favors tensor parallelism, many independent requests favor data-parallel attention, and long prompts favor context parallelism. Reasoning, agentic, and RL-rollout workloads make a fixed choice untenable: a batch that begins as many short requests ends as a few very long ones, so the best layout changes while the same requests run. Serving engines nevertheless fix one layout at launch, because changing it has meant draining requests and restarting workers. We present SPLASH, a serving system that switches the parallel layout of attention while requests are running. It builds on one observation: modern attention, with few or no KV heads, decouples where a request's KV cache lives from how attention weights are sharded. This has two consequences. First, layouts differ only in who owns the weights and the cache, and most of that state already sits where the next layout needs it; SPLASH reuses it, moves the rest in the background of ongoing inference, and hands off at a batch boundary, making a switch nearly free: its median overhead is under 0.51% of the step it runs in. Second, the decoupling exposes a layout that existing engines lack: Decoupled Ownership Parallelism (DOP) shards attention weights as tensor parallelism does while keeping each request's cache on a single owner as data-parallel attention does. DOP replicates neither, offers 27-60% more KV capacity than data-parallel attention, and gives the scheduler a choice when KV memory limits admission. A transition-aware scheduler follows the best of the four layouts as load changes. On B200 GPUs serving GLM-5.3, SPLASH improves end-to-end serving throughput by 1.3-1.73x over fixed-layout deployments, and the same layout regimes appear with DeepSeek-V3.2 on H200 and GLM-5.3-Flash on DCU.

cs.DC↗

arXiv2026

Conditional Dynamical Systems for Image Generation

Image generation is dominated by deep generative models on GPUs, whose computational and energy costs raise sustainability concerns. Emerging non-von Neumann substrates, including quantum, compute-in-memory, photonic, and thermodynamic platforms, promise greater efficiency, yet most work ports conventional neural network architectures onto them and mainly accelerates operations such as matrix multiplication. This does not fully exploit a native capability of many hardware substrates: relaxation toward low-energy states can itself compute at little cost. Building on this primitive, we develop dynamical systems for image generation based on Ising spins and Kuramoto oscillators. The internal states of both models evolve under dynamics with an explicit Lyapunov energy, and a compact decoder renders the final states as images. For conditional generation, we introduce local conditioning: programmed interactions remain fixed, and one class-dependent bias per node reshapes the landscape, avoiding additional reprogramming and calibration costs. On CIFAR-10, the Ising and Kuramoto models reach clean-FID scores of $6.40$ and $5.37$, respectively, with $4096$ nodes. With a CMOS-compatible hardware realization, the dynamical-system core is projected to cost ${\sim}110.6$~nJ per image, and the full computation, even with the decoder on a GPU, outperforms all GPU baselines in latency and energy. These results suggest that energy-descending dynamics on non-von Neumann substrates can serve as generative computation, offering an efficient path beyond GPUs.

cs.ET↗

arXiv2026

CSI-Agent: LLM-Assisted Few-Shot Adaptation for Cross-Domain Wi-Fi CSI Sensing

Wi-Fi channel state information (CSI) has enabled device-free sensing applications such as human activity recognition. However, CSI sensing models remain brittle in cross-domain deployment, where changes in users or environments can produce incorrect predictions. Existing solutions usually treat this problem as an offline model-design problem, by pretraining a stronger representation or applying one fixed adaptation method to the entire target domain. In practice, labeled target data are scarce and different classes may fail in different ways under the same domain shift. To address this, we propose CSI-Agent, an evidence-seeking LLM agent that reformulates cross-domain CSI adaptation as a deployment-time decision-making problem. Rather than processing raw CSI or making sample-level predictions, CSI-Agent summarizes target-domain behavior into sensing-grounded class-level evidence. It establishes a strong target-adaptive default from complementary CSI views and uses an LLM planner to determine whether each class should retain the default or invoke a specialized action. Deterministic verification and bounded execution further reduce unreliable interventions. We evaluate CSI-Agent on four public datasets using five cross-domain splits covering device, user, environment, and compositional shifts. Under 1-shot adaptation, CSI-Agent achieves the best target-domain performance across all splits and improves the average Macro-F1 by about 16\% compared to the strongest baseline method.

cs.AI↗

arXiv2026

SenseAgent: An LLM Agent for Adaptive Cross-Domain IMU Sensing

Deep learning has improved inertial measurement unit (IMU) sensing for mobile and wearable applications. However, an IMU model trained in one domain often becomes unreliable when it is used with a new user, device, or body position. Existing methods usually treat this problem as a static model-design task: they pretrain a stronger representation, add data augmentation, or select one adaptation method before deployment. In practice, the target domain is only gradually observed, labels are scarce, and different domain shifts require different sensing actions. This paper presents SenseAgent, an LLM-guided sensing agent for cross-domain IMU activity recognition. Instead of asking an LLM to classify raw IMU signals, SenseAgent uses the LLM as a runtime planner over sensing tools, source-domain experience memory, online target memory, and verifiers. The agent builds a label-free diagnosis report from the target stream and uses it to decide whether to keep raw inference or invoke specialized tools, including gravity-aware sensing, prototype transfer, and style normalization. Verifiers check source calibration, target-memory reliability, and no-harm criteria before accepting high-risk tool decisions. SenseAgent also supports scarce feedback without retraining the backbone or replacing the label-free route. This design converts cross-domain IMU sensing from a fixed inference pipeline into a closed-loop sensing process that diagnoses target shifts, selects suitable sensing actions, and rejects unsafe adaptations. We evaluate SenseAgent across multiple IMU datasets and deployment shifts. Results show that its verified route selection improves cross-domain sensing, especially under harder placement and compound shifts, and further benefits from limited user feedback.

cs.AI↗

arXiv2026

First-Principles Determination of the QCD Contribution to the Axion-Photon Coupling Using Domain-Wall Fermions

The axion-photon coupling, crucial for experimental axion searches and tests of the strong CP solution, receives a substantial model-independent contribution $\mathcal C_{\rm QCD}$ from QCD dynamics. Next-to-leading-order chiral perturbation theory (NLO ChPT) in different frameworks has yielded puzzling discrepancies of up to $8\%$, motivating precise first-principles calculations. We present an independent lattice QCD determination using a method complementary to the recent background-field calculation. Computing pseudoscalar-to-two-photon three-point functions and exploiting anomalous Ward identities, we separate $\mathcal C_{\rm QCD}$ into an exact anomaly contribution and a light-quark-mass-suppressed correction. The latter is computed using domain-wall fermions, whose excellent chiral symmetry strongly suppresses discretization effects. Working on two near-physical $N_f=2+1$ ensembles with continuum extrapolation, we obtain $\mathcal C_{\rm QCD}^{\rm IS}=1.619(30)$ (isospin-symmetric), $\mathcal C_{\rm QCD}^{\rm IB}=0.347(22)$ (isospin-breaking), and $\mathcal C_{\rm QCD}=1.965(35)$ in total. While direct comparisons with published NLO ChPT predictions reveal apparent tensions, we identify their sources and show that the ChPT results can be reconciled with our lattice determination. Our result provides a first-principles benchmark for the QCD contribution to the axion-photon coupling and a quantitative test of competing ChPT descriptions.

hep-lat↗

arXiv2026

First-principles determination of anomaly-induced pion decay beyond the chiral limit

The two-photon decay of the neutral pion is fixed in the chiral limit by the Adler-Bell-Jackiw anomaly, while nonzero quark masses induce few-percent corrections that must be determined for precision tests of QCD beyond the chiral limit. Using the anomalous PCAC relation, we compute them in lattice QCD as deviations from the exact anomaly condition at $q^2=0$, thereby avoiding both four-point functions and the cancellation of chiral logarithms that limits conventional approaches. Because the correction is proportional to the light-quark masses, both statistical and systematic uncertainties are correspondingly suppressed, making a precision calculation feasible. On two nearly-physical domain-wall ensembles we achieve $\sim1\%$ statistical precision each for the decay width, obtaining $Γ(π^0\toγγ)=8.09(22) eV$ after continuum extrapolation. The $2.3(1.4)\%$ mass correction to the decay amplitude, positive and isospin-breaking dominated, provides the first ab initio confirmation of the $π^0$-$η$-$η'$ mixing enhancement.

hep-lat↗

arXiv2026

DRL-Based Secure Transmission for Rotatable Antenna-Enabled Low-Altitude ISAC Systems

The development of the low-altitude economy has driven innovation in intelligent antenna systems within ISAC systems. In this paper, we investigate a Rotatable Antenna (RA)-enabled low-altitude integrated sensing and communication (ISAC) system. In practical terms, the RA array can flexibly adjust the three-dimensional (3D) beam direction of each antenna to enhance array directional gain, thereby improving the communication security of legitimate mobile users against potential eavesdropping risks from the unmanned aerial vehicle (UAV). Our objective is to maximize the minimum secrecy rate (SR) by jointly optimizing transmit beamforming matrix, transmit and receive RAs' pointing matrices. To this end, an multi-agent proximal policy optimization with three improvement mechanisms (MAPPO-T) algorithm is proposed to cope with the issue of complex multi-agent collaborative decision-making problem. Simulation results show that the introduction of RAs can effectively improve SR performance compared to the traditional fixed orientation antenna (FOA)-based system. In addition, the proposed MAPPO-T algorithm validate the superiority compared to the standard MAPPO algorithm.

eess.SP↗

arXiv2026

Two-nucleon systems at $m_π\approx292$ MeV from lattice QCD

Nucleon-nucleon systems in the $^3S_1$ and the $^1S_0$ channels are studied in lattice quantum chromodynamics at a pion mass of approximately $m_π\approx292$ MeV, employing three $N_f = 2+1$ ensembles with the same pion mass and lattice spacing $a=0.10530(18)$ fm but different spatial volumes. Finite-volume energies of the nucleon-nucleon systems are determined in both the rest frame and a moving frame. The distillation quark smearing method is applied to improve the precision and to ensure the symmetric correlators by using the same interpolating operators at sink and source. The scattering amplitudes are extracted from the finite-volume spectra using the Lüscher's finite-volume method. At the studied pion mass, both the $^3S_1$ (deuteron) and $^1S_0$(di-neutron) channels exhibit a virtual state pole, with binding energies of $6^{+5}_{-3}$ MeV and $11^{+6}_{-5}$ MeV, respectively. To investigate the effects of the left-hand cut, an alternative method -- the Non-Perturbative Hamiltonian framework (NPHF) -- is used for the scattering analysis and yields consistent results with those from the Lüscher method.

hep-lat↗

arXiv2026

Lattice determination of the neutrino background for $J/ψ\rightarrow γ+ \textrm{invisible}$

Searching for dark matter is a primary goal of modern astronomy and particle physics. Invisible decays of heavy quarkonia are particularly promising for probing light dark matter, attracting broad interest due to their unique sensitivity. Experiments searching for radiative invisible decays of the $J/ψ$ have steadily improved upper limits, and upcoming facilities will push sensitivity further--making the precise determination and subtraction of the neutrino background indispensable. Here, we present the first lattice QCD calculation of the Standard Model decay $J/ψ\to γν\barν$, an irreducible background to $J/ψ\rightarrow γ+ \textrm{invisible}$. Our result for the branching fraction is $\operatorname{Br}(J/ψ\rightarrow γν\barν)=1.04(7)(8)\times 10^{-10}$, where the first uncertainty is statistical and the second is our systematic estimate. This work advances lattice-based determinations of neutrino backgrounds to quarkonium invisible decays, delivering an ab initio benchmark for $J/ψ\rightarrow γ+ \textrm{invisible}$. Our approach generalizes to other quarkonium channels (e.g., $Υ/ϕ\rightarrow γ+\textrm{invisible}$) and provides critical theoretical support for dark matter searches at colliders.

hep-lat↗

arXiv2026

Low-energy $DD$ scattering in lattice QCD

We present the first lattice QCD calculation of single-channel $DD$ scattering with quantum numbers $I(J^P)=1(0^+)$ and $0(1^-)$. The calculation is performed on the $2+1$ flavor Wilson-Clover ensembles with a lattice spacing $a\simeq 0.077$ fm and two different pion masses, $m_π\simeq207$ and $305$ MeV. The scattering parameters are determined using the Lüscher's finite volume method. Our results indicate a weak repulsive interaction in the $1(0^+)$ channel and a slightly attractive interaction in the $0(1^-)$ channel. The $S$-wave isovector $DD$ scattering length and effective range, extrapolated to the physical pion mass, are $(-0.25\pm0.08\pm 0.12)$ fm and $(-5.7\pm4.5\pm 1.7)$ fm, respectively.

hep-lat↗

arXiv2026

First-Principles Determination of the Proton-Proton Fusion Matrix Element from Lattice QCD

Proton-proton fusion is the fundamental weak reaction initiating stellar energy production, and a first-principles determination of its matrix element remains a long-standing goal of nuclear theory. We present a lattice QCD calculation of the pp fusion matrix element at m_pi~432 MeV. We implement Lellouch-Luscher (LL) finite-volume (FV) corrections within a 2+J->2 framework, accounting for two-nucleon (2N) rescattering, to relate FV matrix elements to infinite-volume counterparts. Excited-state contamination is suppressed using bi-local nucleon-nucleon interpolating operators and a variational analysis with three lowest momenta. This enables determination of 2N energy spectrum and scattering parameters via Luscher's FV formalism. Before including rescattering effects in the LL factor, we obtain /g_A = 0.984(10), where g_A is the axial charge. The deviation from unity indicates a small nonvanishing 2-body current contribution. Our analysis shows that rescattering effects in LL factors substantially modify the 2-body contribution, while large uncertainties in 2N scattering parameters propagate strongly into FV corrections. Thus, precise determination of the 2-body low-energy constant L_{1,A} remains highly challenging with current lattice inputs. Despite the large uncertainty, L_{1,A}=6.0(7.1) fm^3 is compatible, at the level of naturalness, with phenomenological extractions. This work demonstrates feasibility and intrinsic challenges of ab initio lattice QCD calculations of weak 2N reactions, and establishes a foundation for future studies at or near the physical pion mass.

hep-lat↗

arXiv2026

Emergence of the $π(1300)$ Resonance from Lattice QCD

The mass of the lightest hadron in nature, the pion, is one seventh of that of the nucleon and one tenth of the mass of its first excited state, the $π(1300)$. This enormous energy difference opens an interesting window into the confinement of quarks and the structure of the lightest hadrons. In this Letter, we provide the first calculation of resonance parameters of the $π(1300)$ from lattice quantum chromodynamics (QCD). For this purpose, recently derived state-of-the-art tools are adapted and applied both in the construction of three-hadron operators and for mapping finite-volume spectra to infinite-volume amplitudes, subsequently analytically continuing these to complex energies. For our heavy pion mass ensembles, we find a clear signal of the resonance. Making a simple assumption of vanishing pion mass dependence for the three-body force, but incorporating constraints from Chiral Perturbation Theory for all the two-body channels, enables a robust extrapolation to the physical point. Applying model averaging, we extract a pole position of $M_{π(1300)}=(1169\pm46)-i(62_{-62}^{+168})\,\MeV$ supporting values from phenomenology.

hep-lat↗

arXiv2026

MTGenRec: An Efficient Distributed Training System for Generative Recommendation Models in Meituan

Recommendation is crucial for both user experience and company revenue in Meituan as a leading lifestyle company, and generative recommendation models (GRMs) are shown to produce quality recommendations recently. However, existing systems are limited by insufficient functionality support and inefficient implementations for training GRMs in industrial scenarios. As such, we introduce MTGenRec as an efficient and scalable system for GRM training. Specifically, to handle real-time insertions/deletions of sparse embeddings, MTGenRec employs dynamic hash tables to replace static ones. To improve training efficiency, MTGenRec conducts dynamic sequence balancing to address the computation load imbalances among GPUs and adopts feature ID deduplication alongside automatic table merging to accelerate embedding lookup. Extensive experiments show that MTGenRec improves training throughput by $1.6\times -- 2.4\times$ while achieving good scalability when running over 100 GPUs. MTGenRec has been deployed for many applications in Meituan and is now handling hundreds of millions of requests on a daily basis. On the delivery platform, we observe a 1.22% growth in user order volume and a 1.31% enhancement in online PV_CTR.

cs.DC↗

arXiv2026

MTServe: Efficient Serving for Generative Recommendation Models with Hierarchical Caches

Generative recommendation (GR) offers superior modeling capabilities but suffers from prohibitive inference costs due to the repeated encoding of long user histories. While cross-request Key-Value (KV) cache reuse presents a significant optimization opportunity, the massive scale of individual user states creates a storage explosion that far exceeds physical GPU limits. We propose MTServe, a hierarchical cache management system that virtualizes GPU memory by leveraging host RAM as a scalable backup store. To bridge the I/O gap between tiers, MTServe introduces a suite of system-level optimizations, including a hybrid storage layout, an asynchronous data transfer pipeline, and a locality-driven replacement policy. On both public and production datasets, MTServe delivers up to 3.1* speedup while maintaining near-perfect hit ratios (>98.5%).

cs.LG↗

arXiv2026

Suitable sets for topological groups revisited

A discrete subset $S$ of a topological group $G$ is called a {\it suitable set} for $G$ if $S\cup \{e\}$ is closed in $G$ and the subgroup generated by $S$ is dense in $G$, where $e$ is the identity element of $G$. In this paper, the existence of suitable sets in topological groups is studied. It is proved that, for a non-separable $k_ω$-space $X$ without non-trivial convergent sequences, the $snf$-countability of $A(X)$ implies that $A(X)$ does not have a suitable set, which gives a partial answer to \cite[Problem 2.1]{TKA1997}. Moreover, the existence of suitable sets in some particular classes of linearly orderable topological groups is considered, where Theorem~\ref{t4} provides an affirmative answer to \cite[Problem 4.3]{ST2002}. Then, topological groups with an $ω^ω$-base are discussed, and every linearly orderable topological group with an $ω^ω$-base being metrizable is proved; thus it has a suitable set. Further, it follows that each topological group $G$ with an $ω^ω$-base has a suitable set whenever $G$ is a $k$-space, which gives a generalization of a well-known result in \cite{CM}. Finally, some cardinal invariant of topological groups with a suitable set are provided. Some results of this paper give some partial answers to some open problems posed in~\cite{DTA} and~\cite{TKA1997} respectively.

math.GN↗

arXiv2026

Lattice QCD study of the $K^*(892)$ resonance at the physical point

We present a lattice QCD study of the $K^*(892)$ resonance using eight $N_f=2+1$ Wilson-Clover ensembles with three lattice spacings and six pion masses ranging from 135 to 320 MeV. For each ensemble, a large number of finite volume energy levels in the $P$-wave $Kπ$ channel are determined. The energy dependence of the scattering phase shift is then obtained from Lüscher's finite-volume method. To systematically assess parametrization dependence, the amplitude is described using three different models, which yield consistent results. The resulting phase shifts show a clear resonant behavior for all ensembles, and the corresponding $K^*(892)$ resonance pole is identified on the second Riemann sheet in the complex energy plane. The pole positions are extrapolated to the physical pion mass and the continuum limit, yielding a $K^*(892)$ resonance located at $\sqrt{s_0} = [883(22)-i20(13)]\mathrm{MeV}$, which is in excellent agreement with the experimental value. This study provides a first-principles QCD determination of the $K^*(892)$ mass and width with controlled systematic uncertainties.

hep-lat↗

arXiv2026

Universal Decay of Mutual Information and Conditional Mutual Information in Gapped Pure- and Mixed-State Quantum Matter

For spin and fermionic systems in any spatial dimension, we establish that the superpolynomial decay behavior of mutual information and conditional mutual information is a universal property of gapped pure- and mixed-state phases; i.e., all systems in such a phase possess this property if one system in this phase possesses this property. We further demonstrate that the (conditional) mutual information indeed decays superpolynomially in a large class of phases, including chiral phases. As a by-product, we sharpen the notion of mixed-state phases.

cond-mat.str-el↗