arXiv subjects

Jin Sun

Publications and source records attributed to Jin Sun.

At least 37 records · Page 2Linked to original sources

arXiv2026

Sharp long distance upper bounds for solutions of Leibenson's equation on Riemannian manifolds

We consider on Riemannian manifolds the Leibenson equation $\partial _{t}u=Δ_{p}u^{q}$ that is also known as a doubly nonlinear evolution equation. We prove sharp upper estimates of weak subsolutions to this equation on Riemannian manifolds with non-negative Ricci curvature in the whole range of $p>1$ and $q>0$ satisfying $q(p-1)<1$. In this way, we improve the result of \cite{Grigoryan2024a} and prove Conjecture 1.2 from \cite{Grigoryan2024a}.

math.AP↗

arXiv2026

A Multi-Stage Deep Learning Framework with PKCP-MixUp Augmentation for Pediatric Liver Tumor Diagnosis Using Multi-Phase Contrast-Enhanced CT

Pediatric liver tumors are one of the most common solid tumors in pediatrics, with differentiation of benign or malignant status and pathological classification critical for clinical treatment. While pathological examination is the gold standard, the invasive biopsy has notable limitations: the highly vascular pediatric liver and fragile tumor tissue raise complication risks such as bleeding; additionally, young children with poor compliance require anesthesia for biopsy, increasing medical costs or psychological trauma. Although many efforts have been made to utilize AI in clinical settings, most researchers have overlooked its importance in pediatric liver tumors. To establish a non-invasive examination procedure, we developed a multi-stage deep learning (DL) framework for automated pediatric liver tumor diagnosis using multi-phase contrast-enhanced CT. Two retrospective and prospective cohorts were enrolled. We established a novel PKCP-MixUp data augmentation method to address data scarcity and class imbalance. We also trained a tumor detection model to extract ROIs, and then set a two-stage diagnosis pipeline with three backbones with ROI-masked images. Our tumor detection model has achieved high performance (mAP=0.871), and the first stage classification model between benign and malignant tumors reached an excellent performance (AUC=0.989). Final diagnosis models also exhibited robustness, including benign subtype classification (AUC=0.915) and malignant subtype classification (AUC=0.979). We also conducted multi-level comparative analyses, such as ablation studies on data and training pipelines, as well as Shapley-Value and CAM interpretability analyses. This framework fills the pediatric-specific DL diagnostic gap, provides actionable insights for CT phase selection and model design, and paves the way for precise, accessible pediatric liver tumor diagnosis.

eess.IV↗

arXiv2025

Parabolic Frequency on Gaussian Spaces and Unique Continuation

We establish an almost-monotonicity formula for a parabolic frequency on Gaussian spaces for solutions of the Ornstein-Uhlenbeck heat equation with lower-order terms: $$\partial_t u = L_γu + b(x,t) \cdot \nabla u + c(x,t)u, $$ where $L_γ= Δ- x \cdot \nabla$ is the Ornstein-Uhlenbeck operator. In contrast to classical results that require $b$ and $c$ to be bounded, we only assume that $b$ is bounded and $c$ satisfies a linear growth condition, while the solution $u$ is allowed to have at most exponential quadratic growth. The key innovation is a weighted $L^2$ framework that uses the backward Mehler kernel as a weight, which naturally encodes the underlying measure and compensates for the unbounded coefficients. From the frequency monotonicity, we derive the strong unique continuation principle. This extends Poon's seminal results and complements recent geometric generalizations by Colding and Minicozzi in the context of Gaussian measure spaces. We further apply our framework to establish unique continuation for equations with potentials exhibiting quadratic growth or certain singularities.

math.AP↗

arXiv2025

Collider Probes of Four-Lepton Final States in Maximally Flavor-Violating $U(1)_{L_μ-L_τ}$ Model

We investigate the collider signatures of the maximally flavor-violating $U(1)_{L_μ-L_τ}$ model, where a new gauge boson $Z^\prime$ and scalar triplets induce lepton flavor-changing interactions in the $μ$-$τ$ sector. Focusing on four-lepton final states at multi-TeV lepton colliders, we conduct a detailed analysis of cross sections, asymmetries, and polarization effects. We show that the signal cross section is highly sensitive to $m_{Z^\prime}$ and the effective parameters $\tilde{g}/m_{Z^\prime}$, while remaining largely insensitive to the triplet Yukawa couplings within the phenomenologically allowed region. The forward-backward asymmetry exhibits a characteristic monotonic dependence on $m_{Z^\prime}$, and beam polarization can significantly suppress Standard Model backgrounds while enhancing new physics contributions. We find that over the phenomenologically allowed parameter space, the predicted observables remain highly sensitive to the underlying model parameters. These results demonstrate that multi-lepton final states are powerful probes of the $U(1)_{Lμ- L_τ}$ framework and offer valuable guidance for future searches at muon and electron-positron colliders.

hep-ph↗

arXiv2025

Optimal Investment, Consumption, and Insurance with Durable Goods under Stochastic Depreciation Risk

We study an infinite-horizon optimal investment, consumption and insurance problem for an economic agent who consumes a perishable and a durable good. The agent trades in a risk-free asset, a risky asset, and a durable good whose price follows a correlated diffusion, while the stock of the durable good depreciates deterministically and is subject to insurable Poisson loss shocks. The agent can partially hedge these shocks via an insurance contract with loading and chooses optimal perishable consumption, portfolio holdings, and insurance coverage to maximise expected discounted CRRA utility. Exploiting the homogeneity of the problem, we reduce the Hamilton--Jacobi--Bellman equation to a static one-dimensional optimisation over constant portfolio shares and derive a semi-explicit optimal strategy. We then prove a verification theorem for the associated jump-diffusion wealth process with insurance, establishing the existence and optimality of this constant-fraction strategy under explicit transversality conditions for both risk-aversion regimes $0<γ<1$ and $γ>1$. Numerical experiments illustrate the impact of stochastic depreciation risk and insurance loading on the optimal allocation to financial assets, durable goods, and insurance coverage.

econ.GN↗

arXiv2025

Predictions for CP violation in anti-triplet beauty baryon to charmonium decays

Motivated by the recent 3.9$σ$ evidence for CP violation from the LHCb collaboration in decays of an anti-triplet beauty baryon to a charmonium, an octet baryon, and a pseudoscalar meson, we perform, for the first time, a systematic analysis of this class of decays within the framework of flavor $SU(3)$ symmetry. Several predictions for branching ratios and CP violating relations which can be tested in future experiments are found, in particular $ΔA_{CP} = A_{CP}(Λ_b^0 \to p π^- J/ψ) - A_{CP}(Λ_b^0 \to p K^- J/ψ) = A_{CP}(Λ_b^0 \to n π^0 J/ψ) - A_{CP}(Λ_b^0 \to (n K_S, n K_L) J/ψ)$. Our results provide guidance to test the availability of $SU(3)$ symmetry and search for possible CP violation effects in this class of decays.

hep-ph↗

arXiv2025

Sharp Fundamental Gap Estimate on Convex Domains in Gaussian Spaces

We prove a sharp lower bound for the fundamental gap on convex domains in Gaussian spaces, the difference between the first two eigenvalues of the Ornstein-Uhlenbeck operator with Dirichlet boundary conditions. Our main result establishes that the gap is bounded below by the gap of the corresponding one-dimensional model, confirming the Gaussian analogue of the fundamental gap conjecture. Furthermore, we demonstrate that the normalized gap of the one-dimensional model is monotonically increasing with the diameter and prove the sharpness of our estimate. Beyond the fundamental gap, we also establish improved log-concavity properties for the Dirichlet heat kernel on convex domains in Gaussian spaces. Our work on Gaussian spaces complements the existing results of Andrews and Clutterbuck and Ni for Euclidean domains, as well as the work of Seto, Wang, and Wei for spherical domains.

math.SP↗

arXiv2025

Cogenesis by a sliding pNGB with symmetry non-restoration

We demonstrate that a pseudo-Nambu-Goldstone boson (pNGB) with an initial misalignment angle can drive successful spontaneous baryogenesis and serve as a dark matter (DM) candidate, provided the corresponding global symmetry is non-restored at high temperature. A key feature of this mechanism is the presence of a slowly sliding phase in the pNGB's motion, during which it traverses rapidly diminishing potential barriers, generating and freezing the baryon asymmetry, while transitioning into the kination phase and then an oscillatory phase. Just before the `would-be' oscillation temperature, parametric resonance effectively fragments the homogeneous mode into fluctuations that ultimately constitute the final DM abundance. By considering a dimension-five explicit breaking operator, we find that the predicted pNGB mass and decay constant are approximately $5\,{\rm eV}$ and $3\times10^6\,{\rm GeV}$, respectively, while the radial mode has a light mass $\mathcal{O}(10)\,{\rm MeV}$ and a small mixing $\mathcal{O}(10^{-4})$ with the Higgs boson. Applied to the Majoron in the type-I seesaw model, this scenario requires the heaviest right-handed neutrino to be as light as $0.1$ to $100\,{\rm GeV}$. These predictions can be tested through kaon experiments, heavy neutral lepton searches, the LHC, and future colliders.

hep-ph↗

arXiv2025

Probing maximal flavor changing $Z'$ in $U(1)_{L_μ-L_τ}$ at $μ$TRISTAN

We explore the potential to detect the $U(1)_{L_μ-L_τ}$ model featuring triplet scalars $Δ$ at the $μ$TRISTAN collider. The new gauge boson $Z'$, arising from the spontaneous breaking of $U(1)_{L_μ-L_τ}$, can exhibit maximal flavor changing interactions under the exchange symmetry, while $Δ$ mediates the flavor conserving interactions. The absence of muon $(g-2)_μ$ can be explained by interference effects arising from opposite contributions of $Z'$ and $Δ$, with similar interference patterns also manifesting in the tau decay process $τ\to μν\barν$. These counteracting effects render the model phenomenologically interesting and warrant further investigation. For the mass $m_{Z'}$ in the range of hundreds of GeV, we find that $μ^+μ^+$ and $μ^+e^-$ collider at the $μ$TRISTAN can probe many regions inaccessible to current experiments and offer greater projected sensitivity than opposite-sign muon colliders. This suggests that $μ$TRISTAN can serve as complementary exploration to the $U(1)_{L_μ-L_τ}$ model, providing compelling motivation for the next generation of high-energy lepton colliders.

hep-ph↗

arXiv2025

Probing $B^+ \to K^+$ semi-leptonic FCNC decay with new physics effects under PQCD approach

Recently, the Belle II Collaboration reported the branching fraction $\mathcal{B}(B^+ \to K^+ ν\barν)=(2.3\pm0.7)\times10^{-5}$ with a significance of $3.5σ$, which is $2.7σ$ above the SM expectation. Motivated by this measurement, we calculate this decay channel at the NLO and twist-3 level using the PQCD approach. By combining the lattice QCD data and our results, we obtain form factors with improved accuracy. Using these form factors, we precisely estimate the branching ratios of $B^+ \to K^+$ semileptonic FCNC decays, including $B^+ \to K^+ν\barν$ and $B^+ \to K^+\ell^+\ell^-$. To explain the anomalies in these two processes, we introduce a leptoquark model as a new physics scenario. Using five possible types of leptoquarks, we successfully explain the latest experimental measurements, and further constraints on the leptoquarks are derived.

hep-ph↗

arXiv2025

Lepton collider imprints of Inelastic dark matter model

We explore the potential for detecting the inelastic dark model (DM) with an additional $U(1)_D$ gauge symmetry at various types of lepton colliders. The new gauge boson $Z'$ resulting from the spontaneous breaking of $U(1)_D$ can act as a portal connecting the Standard Model fermions and DM fermions $χ$, thereby facilitating the production of $Z'$ and its decay into DM fermions. The mass difference between the excited DM fermion $χ_2$ and the ground DM fermion $χ_1$ induces the subsequent decays $χ_2\to χ_1 +\text{vis}$, where $χ_2$ and $χ_1$ serve as long lived particles and DM candidate, respectively. For the inelastic DM with a mass $m_{χ_1}$ in the range of (1-100) GeV, we find that the future lepton colliders can probe many regions not accessible by current experiments and provide greater projected sensitivity than the LHC and Belle in previous studies. This suggests that future colliders can provide complementary exploration of the inelastic dark matter model.

hep-ph↗

arXiv2025

Concept-Centric Token Interpretation for Vector-Quantized Generative Models

Vector-Quantized Generative Models (VQGMs) have emerged as powerful tools for image generation. However, the key component of VQGMs -- the codebook of discrete tokens -- is still not well understood, e.g., which tokens are critical to generate an image of a certain concept? This paper introduces Concept-Oriented Token Explanation (CORTEX), a novel approach for interpreting VQGMs by identifying concept-specific token combinations. Our framework employs two methods: (1) a sample-level explanation method that analyzes token importance scores in individual images, and (2) a codebook-level explanation method that explores the entire codebook to find globally relevant tokens. Experimental results demonstrate CORTEX's efficacy in providing clear explanations of token usage in the generative process, outperforming baselines across multiple pretrained VQGMs. Besides enhancing VQGMs transparency, CORTEX is useful in applications such as targeted image editing and shortcut feature detection. Our code is available at https://github.com/YangTianze009/CORTEX.

cs.CV↗

arXiv2025

ZooplanktonBench: A Geo-Aware Zooplankton Recognition and Classification Dataset from Marine Observations

Plankton are small drifting organisms found throughout the world's oceans and can be indicators of ocean health. One component of this plankton community is the zooplankton, which includes gelatinous animals and crustaceans (e.g. shrimp), as well as the early life stages (i.e., eggs and larvae) of many commercially important fishes. Being able to monitor zooplankton abundances accurately and understand how populations change in relation to ocean conditions is invaluable to marine science research, with important implications for future marine seafood productivity. While new imaging technologies generate massive amounts of video data of zooplankton, analyzing them using general-purpose computer vision tools turns out to be highly challenging due to the high similarity in appearance between the zooplankton and its background (e.g., marine snow). In this work, we present the ZooplanktonBench, a benchmark dataset containing images and videos of zooplankton associated with rich geospatial metadata (e.g., geographic coordinates, depth, etc.) in various water ecosystems. ZooplanktonBench defines a collection of tasks to detect, classify, and track zooplankton in challenging settings, including highly cluttered environments, living vs non-living classification, objects with similar shapes, and relatively small objects. Our dataset presents unique challenges and opportunities for state-of-the-art computer vision systems to evolve and improve visual understanding in dynamic environments characterized by significant variation and the need for geo-awareness. The code and settings described in this paper can be found on our website: https://lfk118.github.io/ZooplanktonBench_Webpage.

cs.CV↗

arXiv2025

Induced subgraphs of graphs with large deficiency

The deficiency of a graph $G$, denoted by $\kd(G)$, is the number of vertices not saturated by a maximum matching. A bone $B_i$ is the tree obtained by attaching two pendent edges to each of the end vertices of a path $P_{i}$. The local independence number of $G$, denoted by $α_l(G)$, is defines as the maximum integer $t$ such that $G$ contains an induced star $K_{1,t}$. Motivated by the seminal works of Scott and Seymour~(2016), Chudnovsky et al. (2017, 2020) on finding special types of holes in graphs with large chromatic number and bounded clique number, we establish an analog result by finding special types of bones in graphs with large deficiency and bounded local independence number. Fujita et al. (2006) proved that $\kd(G)\le n-2$ if $G$ is a connected graph with $α_l(G)<n$ and containing no bones. We further establish exact extremal deficiency bounds for connected graphs with bounded local independence number that exclude specific bone configurations. An algorithm that constructs large matchings and establishes an upper bound on the deficiency is also provided.

math.CO↗

arXiv2025

Enhancing Cognition and Explainability of Multimodal Foundation Models with Self-Synthesized Data

Large Multimodal Models (LMMs), or Vision-Language Models (VLMs), have shown impressive capabilities in a wide range of visual tasks. However, they often struggle with fine-grained visual reasoning, failing to identify domain-specific objectives and provide justifiable explanations for their predictions. To address the above challenge, we propose a novel visual rejection sampling framework to improve the cognition and explainability of LMMs using self-synthesized data. Specifically, visual fine-tuning requires images, queries, and target answers. Our approach begins by synthesizing interpretable answers that include human-verifiable visual features. These features are based on expert-defined concepts, and carefully selected based on their alignment with the image content. After each round of fine-tuning, we apply a reward model-free filtering mechanism to select the highest-quality interpretable answers for the next round of tuning. This iterative process of synthetic data generation and fine-tuning progressively improves the model's ability to generate accurate and reasonable explanations. Experimental results demonstrate the effectiveness of our method in improving both the accuracy and explainability of specialized visual classification tasks.

cs.CV↗

arXiv2025

Probing ALP couplings to electroweak gauge bosons

Motivated by the more and more abundant experimental data, we revisit the couplings of axion-like particle (ALP) to electroweak gauge bosons across the ALP mass range from MeV to 100 GeV. The current and future experimental limits on the couplings are extended. The ALP coupling to $W$-bosons gives rise to flavor-changing ALP-quark couplings at the one-loop level. These flavor-changing couplings deserve further investigation under current experimental constraints, especially those stemming from rare meson decays and neutral meson mixing processes. Additionally, flavor-conserving couplings of the ALP to Standard Model (SM) fermions arise at the one-loop level as well from ALP-electroweak gauge boson couplings, even in the absence of tree-level couplings to these SM fermions, with consequent ALP decays to the SM fermions leading to constraints on the ALP-electroweak gauge boson couplings. We also investigate processes relevant to $Z$-boson measurements, such as the invisible decay $Z\to aγ$, subsequent decays $Z\to 3γ$ and $Z\to γll$, as well as constraints from oblique parameters ($S,\, T,\, U$). Our study highlights that rare two-body decays of pseudoscalar mesons offer the most sensitive probes of ALP couplings to electroweak gauge bosons from the loop-induced flavor-violating interactions for ALP masses below the kinematic threshold, while $Z$-boson decays complementarily explore larger ALP masses. Future lepton colliders, such as CEPC and FCC-ee operating at the $Z$-pole, along with SHiP, provide further opportunities to probe ALP couplings to electroweak gauge bosons.

hep-ph↗

arXiv2025

Analysis of Charmed Baryon Decays with Strong Phases under SU(3) Symmetry

The SU(3) analysis is considered a powerful tool in charmed baryon decays. Motivated by recent measurements of anti-triplet charmed baryon two-body decays from the Belle, Belle II, and BESIII Collaborations, we have finally determined the last two IRA form factors, $f^{a\prime}$ and $g^{a\prime}$, which were absent in previous work. By considering both real and complex form factor cases in our work, we find that the phases of the form factors are necessary and that complex form factors can explain the experimental data well. Using the fitted form factors, we further numerically study the equivalence of the SU(3) irreducible representation amplitude (IRA) and topological diagrammatic approach (TDA) methods. We find that the IRA and TDA methods can be numerically equivalent with the addition of the new form factors. Based on the conclusions above, and considering some interesting scenarios, the CP violation effects can be predicted in these processes at the order of $O(10^{-3})$. This suggests a promising opportunity to observe CP violation for the first time in charmed baryon decays. Although our predictions depend on some assumptions, considering that the experimental data is far from sufficient to determine CPV through SU(3) analysis, our study is meaningful and instructive for observing CPV at experimental facilities.

hep-ph↗

arXiv2024

Maximal flavor violating $U(1)_{L_μ-L_τ}$ model with singly-charged scalar

The $U(1)_{L_μ-L_τ}$ $Z'$ model has emerged as a promising candidate to address the longstanding muon $(g-2)_μ$ anomaly. Flavor-conserving $Z'$ interactions are subject to stringent constraints from the neutrino trident process and NA64$μ$ experiments, which limit the $Z'$ mass to $m_{Z'}<40$ MeV. To circumvent these constraints, flavor-conserving $Z'$ interactions can be converted into maximal flavor-violating interactions through a discrete exchange symmetry. Maximal flavor-violating $Z'$ interactions contribute to $τ\toμν\barν$ via the neutral current, yet the parameter space for this process conflicts with the $(g-2)_μ$ allowed regions. To resolve this conflict, we propose introducing a singly-charged scalar that mediates via charged current interactions. This scalar is anticipated to produce a negative contribution to the lepton $(g-2)_l$ while concurrently inducing the tau decay $τ\toμν\barν$. Three distinct scenarios arise from the introduction of singly-charged scalars: the $\mathcal{O}_{LL}$ operator, driven by weak singlet and triplet, and the $\mathcal{O}_{LR}$ operator, driven by weak doublet. Our analysis of the phenomenology in these three cases reveals that the tension between the muon $(g-2)_μ$ anomaly and $τ\toμν\barν$ for large $Z'$ masses can be effectively alleviated only by the singly-charged scalars from the weak triplet, whereas the singlet and doublet scenarios fall short. Furthermore, the singly-charged scalars from the weak triplet offer an additional explanation for the electron $(g-2)_e$ anomaly. Our findings indicate that weak triplets could play a crucial role in $Z'$ models, potentially providing valuable insights for future research into $U(1)$ frameworks.

hep-ph↗