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Chunhua Li

Publications and source records attributed to Chunhua Li.

At least 19 recordsLinked to original sources
arXiv2026

Resonant Parameters of Vector Charmonium-like States above 4.4 GeV

We analysis the $\sqrt{s}$-dependent line shapes of the $e^+e^-\to D_s^{+}D_{s1}^{*-}(2536)$, $D_s^{+}D_{s2}^{*-}(2573)$, $ϕχ_{c1,2}$, $K^+K^-J/ψ$, $K_S^0 K_S^0 J/ψ$, and $K^+K^-ψ(2S)$ cross sections measured by the BESIII experiment using the four resonant structures $ψ(4230)$, $ψ(4500)$, $ψ(4660)$, and $ψ(4710)$, by performing a simultaneous $χ^2$-minimized fit. Their masses and widths are obtained. We find that the processes $e^+e^-\to D_s^{+}D_{s1}^{*-}(2536)$, $e^+e^-\to D_s^{+}D_{s2}^{*-}(2573)$, and $e^+e^-\to ϕχ_{c1,2}$ are all dominantly produced via the $ψ(4660)$ and $ψ(4710)$ decays.

hep-ex↗
arXiv2025

Status and prospects of the $χ_{c1}(3872)$ at BESIII

The $χ_{c1}(3872)$ serves as a pivotal role for understanding hadronic structures, remaining one of the most extensively studied exotic particles despite the experimental discovery of numerous unconventional hadronic states. Sustained experimental and theoretical investigations into the particle over the past two decades have propelled its study into a high-precision regime, marked by refined measurements of its decay dynamics and line shape, thereby offering critical insights to resolve longstanding debates between molecular, tetraquark, hybrid, and charmonium interpretations of this particle. The BESIII experiment has made seminal contributions to the study of the $χ_{c1}(3872)$, leveraging its unique capabilities in high-statistics data acquisition and low-background condition. This article gives a concise review and prospects of the study of the $χ_{c1}(3872)$ from the BESIII experiment.

hep-ex↗
arXiv2025

Thermal conductivity of boron arsenide above 2100 watts per meter per Kelvin at room temperature

Boron arsenide (BAs) single crystals had been previously reported to have thermal conductivity of 1500 W/mK at room temperature. Now we achieved thermal conductivity above 2100 W/mK at room temperature in BAs crystals due to much lower concentration of impurities Si, C, and O grown from purified arsenic. We also observed a T-1.8 dependence of the thermal conductivity, suggesting a more significant contribution from four-phonon scatterings than suggested by previous theory. We found that our experimental result can be fit with a modified theoretical calculation by tuning down the three-phonon scattering for phonons in the 4-8 THz range, although current phonon transport theory cannot provide a physical explanation. Such an advance will not only attract more effort on growing BAs single crystals and studying their practical applications but also stimulate theoretical work to predict more materials with possibly even higher thermal conductivities.

cond-mat.mtrl-sci↗
arXiv2024

A Role-specific Guided Large Language Model for Ophthalmic Consultation Based on Stylistic Differentiation

Ophthalmology consultations are crucial for diagnosing, treating, and preventing eye diseases. However, the growing demand for consultations exceeds the availability of ophthalmologists. By leveraging large pre-trained language models, we can design effective dialogues for specific scenarios, aiding in consultations. Traditional fine-tuning strategies for question-answering tasks are impractical due to increasing model size and often ignoring patient-doctor role function during consultations. In this paper, we propose EyeDoctor, an ophthalmic medical questioning large language model that enhances accuracy through doctor-patient role perception guided and an augmented knowledge base with external disease information. Experimental results show EyeDoctor achieves higher question-answering precision in ophthalmology consultations. Notably, EyeDoctor demonstrated a 7.25% improvement in Rouge-1 scores and a 10.16% improvement in F1 scores on multi-round datasets compared to second best model ChatGPT, highlighting the importance of doctor-patient role differentiation and dynamic knowledge base expansion for intelligent medical consultations. EyeDoc also serves as a free available web based service and souce code is available at https://github.com/sperfu/EyeDoc.

cs.CL↗
arXiv2024

Determination of the resonant parameters of chi_c0(3915) with global fit

The chi_c0(3915) was observed firstly by the Belle experiment in the omega J/psi invariant mass spectrum in the process B -> K omegaJ/psi, and then confirmed by the Babar experiment. The two experiments reported the resonant parameters of this particle in the both processes gammagamma -> omegaJ/psi and B -> K omega J/psi by assuming chi_c0(3915) as a S-wave Breit-Wigner resonance. We perform a global fit to the distributions of invariant mass of omega J/psi measured by the Belle and Babar experiments, and incorporate the measurement by the LHCb experiment additionally to extract the mass and width of chi_c0(3915). We obtain M = 3921.0 +/- 0.9 MeV/c2 and Gamma = 17.9 +/- 2.4 MeV which are consistent with the values on PDG within one standard deviation but with improved precision.

hep-ex↗
arXiv2022

Visualizing bulk and edge photocurrent flow in anisotropic Weyl semimetals

Materials that rectify light into current in their bulk are desired for optoelectronic applications. In inversion-breaking Weyl semimetals, bulk photocurrents may arise due to nonlinear optical processes that are enhanced near the Weyl nodes. However, the photoresponse of these materials is commonly studied by scanning photocurrent microscopy (SPCM), which convolves the effects of photocurrent generation and collection. Here, we directly image the photocurrent flow inside the type-II Weyl semimetals WTe2 and TaIrTe4 using high-sensitivity quantum magnetometry with nitrogen-vacancy center spins. We elucidate an unknown mechanism for bulk photocurrent generation termed the anisotropic photothermoelectric effect (APTE), where unequal thermopowers along different crystal axes drive intricate circulations of photocurrent around the photoexcitation. Using simultaneous SPCM and magnetic imaging at the sample's interior and edges, we visualize how the APTE stimulates the long-range photocurrent collected in our Weyl semimetal devices through the Shockley-Ramo theorem. Our results highlight an overlooked, but widely relevant source of current flow and inspire novel photodetectors using homogeneous materials with anisotropy.

cond-mat.mtrl-sci↗
arXiv2022

Class-attention Video Transformer for Engagement Intensity Prediction

In order to deal with variant-length long videos, prior works extract multi-modal features and fuse them to predict students' engagement intensity. In this paper, we present a new end-to-end method Class Attention in Video Transformer (CavT), which involves a single vector to process class embedding and to uniformly perform end-to-end learning on variant-length long videos and fixed-length short videos. Furthermore, to address the lack of sufficient samples, we propose a binary-order representatives sampling method (BorS) to add multiple video sequences of each video to augment the training set. BorS+CavT not only achieves the state-of-the-art MSE (0.0495) on the EmotiW-EP dataset, but also obtains the state-of-the-art MSE (0.0377) on the DAiSEE dataset. The code and models have been made publicly available at https://github.com/mountainai/cavt.

cs.CV↗
arXiv2022

Colossal phonon drag enhanced thermopower in lightly doped diamond

Diamond is one of the most studied materials because of its unique combination of remarkable electrical, mechanical, thermal and optical properties. Using a fully self-consistent ab initio theory of coupled electron-phonon transport, we reveal another striking behavior: a huge drag enhancement of the thermopower of lightly doped diamond. Thermopower values of around 100,000 microvolts per Kelvin are found at 100 K, significantly exceeding the highest previously measured value in the correlated metal FeSb2, and occurring at much higher temperatures. The enormous thermopower in diamond arises primarily from exceptionally weak anharmonic phonon decay around and below 100 K that facilitates efficient momentum exchange between charge carriers and phonons through electron-phonon interactions. Exceedingly large thermoelectric power factors are also identified. This work gives insights into the physics of the coupled electron-phonon system in solids and advances our understanding of thermoelectric transport in the regime of strong drag.

cond-mat.mtrl-sci↗
arXiv2022

The elphbolt ab initio solver for the coupled electron-phonon Boltzmann transport equations

elphbolt is a modern Fortran (2018 standard) code for efficiently solving the coupled electron-phonon Boltzmann transport equations from first principles. Using results from density functional and density functional perturbation theory as inputs, it can calculate the effect of the non-equilibrium phonons on the electronic transport (phonon drag) and non-equilibrium electrons on the phononic transport (electron drag) in a fully self-consistent manner and obeying the constraints mandated by thermodynamics. It can calculate the lattice, charge, and thermoelectric transport coefficients for the temperature gradient and electric fields, and the effect of the mutual electron-phonon drag on these transport properties. The code fully exploits the symmetries of the crystal and the transport-active window to allow the sampling of extremely fine electron and phonon wave vector meshes required for accurately capturing the drag phenomena. The coarray feature of modern Fortran, which offers native and convenient support for parallelization, is utilized. The code is compact, readable, well-documented, and extensible by design.

cond-mat.mtrl-sci↗
arXiv2020

How do defects limit the ultrahigh thermal conductivity of BAs? A first principles study

The promise enabled by BAs high thermal conductivity in power electronics cannot be assessed without taking into account the reduction incurred when doping the material. Using first principles calculations, we determine the thermal conductivity reduction induced by different group IV impurities in BAs as a function of concentration and charge state. We unveil a general trend, where neutral impurities scatter phonons more strongly than the charged ones. $\text{C}_{\text{B}}$ and $\text{Ge}_{\text{As}}$ impurities show by far the weakest phonon scattering and retain BAs $κ$ values of over $\sim$ 1000 $\text{W}\cdot\text{K}^{-1}\cdot\text{m}^{-1}$ even up to high densities making them ideal n-type and p-type dopants. Furthermore, going beyond the doping compensation threshold associated to Fermi level pinning triggers observable changes in the thermal conductivity. This informs design considerations on the doping of BAs, and it also suggests a direct way to determine the onset of compensation doping in experimental samples.

cond-mat.mtrl-sci↗
arXiv2020

Large time asymptotics for a cubic nonlinear Schrödinger system in one space dimension, II

This is a sequel to the paper "Large time asymptotics for a cubic nonlinear Schrödinger system in one space dimension" by the same authors. We continue to study the Cauchy problem for the two-component system of cubic nonlinear Schrödinger equations in one space dimension. We provide criteria for large time decay or non-decay in $L^2$ of the small amplitude solutions in terms of the Fourier transforms of the initial data.

math.AP↗
arXiv2019

Determination of the absolute branching fractions of X(3872) decays

We report the first determination of the absolute branching fractions of the X(3872) decays by globally analyzing the measurements provided by the Belle, BaBar, BESIII, and LHCb experiments. The branching fractions of X(3872) to pi^+pi^- J/psi and D*0D0bar+c.c. are found to be (4.1^{+1.9}_{-1.1})% and (52.4^{+25.3}_{-14.3})%, respectively. The branching fractions of the decays X(3872) to gamma J/psi, gamma psi', omega J/psi, and pi^0 chi_{c1} are also determined. The global fit implies that the fraction of X(3872) decays which are not observed in experiments is (31.9_{-31.5}^{+18.1})%, which indicates that there is still a lot of room for searching for new decay modes of the X(3872). With the branching fraction, we determine the production cross section of e+e- to gamma X(3872) at center-of-mass energy 4.226 GeV.

hep-ex↗
arXiv2019

Thermal expansion coefficient and lattice anharmonicity of cubic boron arsenide

Recent measurements of an unusual high thermal conductivity of around 1000 W m-1 K-1 at room temperature in cubic boron arsenide (BAs) confirm predictions from theory and suggest potential applications of this semiconductor compound for thermal management applications. Knowledge of the thermal expansion coefficient and Grüneisen parameter of a material contributes both to the fundamental understanding of its lattice anharmonicity and to assessing its utility as a thermal-management material. However, previous theoretical calculations of the thermal expansion coefficient and Grüneisen parameter of BAs yield inconsistent results. Here we report the linear thermal expansion coefficient of BAs obtained from the X-ray diffraction measurements from 300 K to 773 K. The measurement results are in good agreement with our ab initio calculations that account for atomic interactions up to fifth nearest neighbours. With the measured thermal expansion coefficient and specific heat, a Grüneisen parameter of BAs of 0.84 +/- 0.09 is obtained at 300 K, in excellent agreement with the value of 0.82 calculated from first principles and much lower than prior theoretical results. Our results confirm that BAs exhibits a better thermal expansion coefficient match with commonly used semiconductors than other high-thermal conductivity materials such as diamond and cubic boron nitride.

cond-mat.mtrl-sci↗
arXiv2019

Large time asymptotics for a cubic nonlinear Schrödinger system in one space dimension

We consider a two-component system of cubic nonlinear Schrödinger equations in one space dimension. We show that each component of the solutions to this system behaves like a free solution in the large time, but there is a strong restriction between the profiles of them. This turns out to be a consequence of non-trivial long-range nonlinear interactions.

math.AP↗
arXiv2018

On the scattering problem for the nonlinear Schrödinger equation with a potential in 2D

We consider the scattering problem for the nonlinear Schrödinger equation with a potential in two space dimensions. Appropriate resolvent estimates are proved and applied to estimate the operator $A(s)$ appearing in commutator relations. The equivalence between the operators $\left(-Δ_{V}\right)^{\frac{s}{2}}$ and $\left(-Δ\right)^{\frac{s}{2}}$ in $L^{2}$ norm sense for $0\leq s <1$ is investigated by using free resolvent estimates and Gaussian estimates for the heat kernel of the Schrödinger operator $-Δ_{V}$. Our main result guarantees the global existence of solutions and time decay of the solutions assuming initial data have small weighted Sobolev norms. Moreover, the global solutions obtained in the main result scatter.

math.AP↗