Liaoning University
Video-to-Audio generation has made remarkable strides in automatically synthesizing sound for video. However, existing evaluation metrics, which focus on semantic and temporal alignment, overlook a critical failure mode: models often generate acoustic events, particularly speech and music, that have no corresponding visual source. We term this phenomenon Insertion Hallucination and identify it as a systemic risk driven by dataset biases, such as the prevalence of off-screen sounds, that remains completely undetected by current metrics. To address this challenge, we first develop a systematic evaluation framework that employs a majority-voting ensemble of multiple audio event detectors. We also introduce two novel metrics to quantify the prevalence and severity of this issue: IH@vid (the fraction of videos with hallucinations) and IH@dur (the fraction of hallucinated duration). Building on this, we propose Posterior Feature Correction, a novel training-free inference-time method that mitigates IH. PFC operates in a two-pass process: it first generates an initial audio output to detect hallucinated segments, and then regenerates the audio after masking the corresponding video features at those timestamps. Experiments on several mainstream V2A benchmarks first reveal that state-of-the-art models suffer from severe IH. In contrast, our PFC method reduces both the prevalence and duration of hallucinations by over 50\% on average, without degrading, and in some cases even improving, conventional metrics for audio quality and temporal synchronization. Our work is the first to formally define, systematically measure, and effectively mitigate Insertion Hallucination, paving the way for more reliable and faithful V2A models.
By analyzing 6.32 fb16.32~\mathrm{fb}^{-1} of e+ee^+e^- annihilation data collected at the center-of-mass energies between 4.178 and 4.226\,GeV with the BESIII detector, we determine the branching fraction of the leptonic decay Ds+τ+ντD_s^+\to\tau^+\nu_\tau with τ+π+π0νˉτ\tau^+\to\pi^+\pi^0\bar \nu_\tau, to be $\mathcal{B}_{D_s^+\to\tau^+\nu_\tau}=(5.29\pm0.25_{\rm stat}\pm0.20_{\rm syst})\%$. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element Vcs|V_{cs}| and the Ds+D_s^+ decay constant fDs+f_{D^+_s} to be fDs+Vcs=(244.8±5.8stat±4.8syst) MeVf_{D_s^+}|V_{cs}|=(244.8\pm5.8_{\rm stat}\pm4.8_{\rm syst})~\mathrm{MeV} using the known values of the τ+\tau^+ and Ds+D_s^+ masses as well as the Ds+D_s^+ lifetime, together with our branching fraction measurement. Combining with the value of Vcs|V_{cs}| obtained from a global fit in the standard model and fDs+f_{D_s^+} from lattice quantum chromodynamics, we obtain fDs+=(251.6±5.9stat±4.9syst)f_{D_s^+}=(251.6\pm5.9_{\rm stat}\pm4.9_{\rm syst})\,MeV and $|V_{cs}| = 0.980\pm0.023_{\rm stat}\pm0.019_{\rm syst}$.
Model averaging has demonstrated superior performance for ensemble forecasting in high-dimensional framework, its extension to incomplete datasets remains a critical but underexplored challenge. Moreover, identifying the parsimonious model through averaging procedure in quantile regression demands urgent methodological innovation. In this paper, we propose a novel model averaging method for high-dimensional quantile regression with nonignorable missingness. The idea is to relax the parametric constraint on the conditional distribution of respondents, which is constructed through the two-phase scheme: (i) a semiparametric likelihood-based estimation for the missing mechanism, and (ii) a semiparametric weighting procedure to combine candidate models. One of pivotal advantages is our SMA estimator can asymptotically concentrate on the optimally correct model when the candidate set involves at least one correct model. Theoretical results show that the estimator achieves asymptotic optimality even under complex missingness conditions. Empirical conclusions illustrate the efficiency of the method.
We study e+e- --> pi+pi-h_c at center-of-mass energies from 3.90 GeV to 4.42 GeV using data samples collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections are measured at 13 energies, and are found to be of the same order of magnitude as those of e+e- --> pi+pi-J/psi but with a different line shape. In the \pi^\pm h_c mass spectrum, a distinct structure, referred to as Z_c(4020), is observed at 4.02 GeV/c^2. The Z_c(4020) carries an electric charge and couples to charmonium. A fit to the \pi^\pm h_c invariant mass spectrum, neglecting possible interferences, results in a mass of (4022.9\pm 0.8\pm 2.7) MeV/c^2 and a width of (7.9\pm 2.7\pm 2.6) MeV for the Z_c(4020), where the first errors are statistical and the second systematic. No significant Z_c(3900) signal is observed, and upper limits on the Z_c(3900) production cross sections in \pi^\pm h_c at center-of-mass energies of 4.23 and 4.26 GeV are set.
Using e+ee^+e^- collision data collected with the BESIII detector operating at the Beijing Electron Positron Collider, the cross section of e+eπ+πhce^+e^-\to \pi^+\pi^- h_c is measured at 59 points with center-of-mass energy s\sqrt{s} ranging from 4.0094.009 to 4.950 GeV4.950~\mathrm{GeV} with a total integrated luminosity of 22.2 fb122.2~\mathrm{fb}^{-1}. The cross section between 4.34.3 and 4.45 GeV4.45~\mathrm{GeV} exhibits a plateau-like shape and drops sharply around 4.5 GeV4.5~\mathrm{GeV}, which cannot be described by two resonances only. Three coherent Breit-Wigner functions are used to parameterize the s\sqrt{s}-dependent cross section line shape. The masses and widths are determined to be M1=(4223.63.72.9+3.6+2.6) MeV/c2M_1=(4223.6_{-3.7-2.9}^{+3.6+2.6})~\mathrm{MeV}/c^2, Γ1=(58.511.46.5+10.8+6.7) MeV\Gamma_1=(58.5_{-11.4-6.5}^{+10.8+6.7})~\mathrm{MeV}, M2=(4327.418.89.3+20.1+10.7) MeV/c2M_2=(4327.4_{-18.8-9.3}^{+20.1+10.7})~\mathrm{MeV}/c^2, Γ2=(244.127.118.3+34.0+24.2) MeV\Gamma_2=(244.1_{-27.1-18.3}^{+34.0+24.2})~\mathrm{MeV}, and M3=(4467.45.42.7+7.2+3.2) MeV/c2M_3=(4467.4_{-5.4-2.7}^{+7.2+3.2})~\mathrm{MeV}/c^2, Γ3=(62.814.47.0+19.2+9.9) MeV\Gamma_3=(62.8_{-14.4-7.0}^{+19.2+9.9})~\mathrm{MeV}. The first uncertainties are statistical and the second are systematic. The inclusion of the relatively narrower third component proves crucial for reproducing the drop at around 4.5~GeV. The statistical significance of the three-resonance assumption over the two-resonance assumption is greater than 5σ5\sigma.
The spin and parity of the Zc(3900)±Z_c(3900)^\pm state are determined to be JP=1+J^P=1^+ with a statistical significance larger than 7σ7\sigma over other quantum numbers in a partial wave analysis of the process e+eπ+πJ/ψe^+e^-\to \pi^+\pi^-J/\psi. We use a data sample of 1.92 fb1^{-1} accumulated at s=4.23\sqrt{s}=4.23 and 4.26 GeV with the BESIII experiment. When parameterizing the Zc(3900)±Z_c(3900)^\pm with a Flatte-like formula, we determine its pole mass Mpole=(3881.2±4.2stat±52.7syst)MeV/c2M_\textrm{pole}=(3881.2\pm4.2_\textrm{stat}\pm52.7_\textrm{syst})\textrm{MeV}/c^2 and pole width Γpole=(51.8±4.6stat±36.0syst)MeV\Gamma_\textrm{pole}=(51.8\pm4.6_\textrm{stat}\pm36.0_\textrm{syst})\textrm{MeV}. We also measure cross sections for the process e+eZc(3900)+π+c.c.J/ψπ+πe^+e^-\to Z_c(3900)^+\pi^-+c.c.\to J/\psi\pi^+\pi^- and determine an upper limit at the 90\% confidence level for the process e+eZc(4020)+π+c.c.J/ψπ+πe^+e^-\to Z_c(4020)^+\pi^-+c.c.\to J/\psi\pi^+\pi^-.
The spontaneous conversion of muonium to antimuonium is one of the interesting charged lepton flavor violation phenomena offering a sensitive probe of potential new physics and serving as a tool to constrain the parameter space beyond the Standard Model. The Muonium-to-Antimuonium Conversion Experiment (MACE) is designed to utilize a high-intensity muon beam, a Michel electron magnetic spectrometer, a positron transport system, and a positron detection system, to either discover or constrain this rare process with a conversion probability of O(1013)\mathcal{O}(10^{-13}). This article presents an overview of the theoretical framework as well as a detailed description of the experimental design for the search for muonium-to-antimuonium conversion.
We introduce a feasible protocol for generating non-Gaussian (nG) states via postselected von Neumann measurement for continuous-variable quantum information processing. The method uses a two-level system coupled to a Gaussian pointer state through an observable AA with A2=IA^{2}=\mathbb{I}. By operating beyond the weak-coupling regime and selecting different pointer states -- squeezed, coherent, or vacuum -- allows generation of a wide range of nG states, including squeezed cat states, two-mode entangled cat states, approximate Bell states, and a continuum of intermediate nG states with considerable success probabilities. The properties of these states are widely tunable via the postselection-induced weak value and the measurement interaction strength. We characterize the non-Gaussianity via Wigner function negativities and quantify entanglement using linear entropy and concurrence. The protocol offers a scalable route to high-purity nG state engineering.
Fast radio bursts (FRBs) are enigmatic high-energy events with unknown origins, which are observationally divided into two categories, i.e., repeaters and non-repeaters. However, there are potentially a number of non-repeaters that may be misclassified, as repeating bursts are missed due to the limited sensitivity and observation periods, thus misleading the investigation of their physical properties. In this work, we propose a repeater identification method based on the t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm and apply the classification to the first Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) catalog. We find that the spectral morphology parameters, specifically spectral running (rr), represent the key features for identifying repeaters from the non-repeaters. Also, the results suggest that repeaters are more biased towards narrowband emission, whereas non-repeaters are inclined toward broadband emission. We provide a list of 163 repeater candidates, 5 of which are confirmed with an updated repeater catalog from CHIME/FRB. Our findings improve our understanding of the various properties underlying repeaters and non-repeaters, as well as guidelines for future FRB detection and categorization.
We present a comprehensive test of the cosmic distance duality relation (DDR) using a combination of strong gravitational lensing (SGL) time delay measurements and Type Ia supernovae (SNe Ia) data. We investigate three different parameterizations of potential DDR violations. To bridge the gap between SGL and SNe Ia datasets, we implement an artificial neural network (ANN) approach to reconstruct the distance modulus of SNe Ia. Our analysis uniquely considers both scenarios where the absolute magnitude of SNe Ia (MBM_B) is treated as a free parameter and where it is fixed to a Cepheid-calibrated value. Using a sample of six SGL systems and the Pantheon+ SNe Ia dataset, we find no statistically significant evidence for DDR violations across all parameterizations. The consistency of our findings across different parameterizations not only reinforces confidence in the standard DDR but also demonstrates the robustness of our analytical approach.
Traditional Chinese Medicine (TCM) has seen increasing adoption in healthcare, with specialized Large Language Models (LLMs) emerging to support clinical applications. A fundamental requirement for these models is accurate identification of TCM drug ingredients. In this paper, we evaluate how general and TCM-specialized LLMs perform when identifying ingredients of Chinese drugs. Our systematic analysis reveals consistent failure patterns: models often interpret drug names literally, overuse common herbs regardless of relevance, and exhibit erratic behaviors when faced with unfamiliar formulations. LLMs also fail to understand the verification task. These findings demonstrate that current LLMs rely primarily on drug names rather than possessing systematic pharmacological knowledge. To address these limitations, we propose a Retrieval Augmented Generation (RAG) approach focused on ingredient names. Experiments across 220 TCM formulations show our method significantly improves accuracy from approximately 50% to 82% in ingredient verification tasks. Our work highlights critical weaknesses in current TCM-specific LLMs and offers a practical solution for enhancing their clinical reliability.
1
We perform a study of the X(3872)X(3872) lineshape using the data samples of e+eγX(3872)e^+e^-\to\gamma X(3872), X(3872)D0Dˉ0π0X(3872)\to D^0\bar{D}^0 \pi^0 and π+πJ/ψ\pi^+\pi^- J/\psi collected with the BESIII detector. The effects of the coupled-channels and the off-shell D0D^{*0} are included in the parameterization of the lineshape. The lineshape mass parameter is obtained to be MX=(3871.63±0.130.05+0.06)M_{X}=(3871.63\pm 0.13^{+0.06}_{-0.05}) MeV. Two poles are found on the first and second Riemann sheets corresponding to the D0Dˉ0D^{*0}\bar{D}^0 branch cut. The pole location on the first sheet is much closer to the D0Dˉ0D^{*0}\bar{D}^0 threshold than the other, and is determined to be 7.04±0.150.08+0.077.04\pm0.15^{+0.07}_{-0.08} MeV above the D0Dˉ0π0D^0\bar{D}^0\pi^0 threshold with an imaginary part 0.19±0.080.19+0.14-0.19\pm0.08^{+0.14}_{-0.19} MeV.
Discovery of intrinsic two-dimensional (2D) magnetic materials is crucial for understanding the fundamentals of 2D magnetism and realizing next-generation magnetoelectronic and magneto-optical devices. Although significant efforts have been devoted to identifying 2D magnetism by exfoliating bulk magnetic layered materials, seldom studies are performed to synthesize ultra-thin magnetic materials directly for non-layered magnetic materials. Here, we report the successful synthesis of a new type of theoretically proposed 2D metallic ferromagnet 1T FeS2, through the molten-salt-assisted chemical vapor deposition (CVD) method. The long-range 2D ferromagnetic order is confirmed by the observation of a large anomalous Hall effect (AHE) and a hysteretic magnetoresistance. The experimentally detected out-of-plane ferromagnetic ordering is theoretically suported with Stoner criterion. Our findings open up new possibilities to search novel 2D ferromagnets in non-layered compounds and render opportunities for realizing realistic ultra-thin spintronic devices.
We report the most precise measurements to date of the strong-phase parameters between D0D^0 and Dˉ0\bar{D}^0 decays to KS,L0π+πK^0_{S,L}\pi^+\pi^- using a sample of 2.93 fb1^{-1} of e+ee^+e^- annihilation data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider. Our results provide the key inputs for a binned model-independent determination of the Cabibbo-Kobayashi-Maskawa angle γ/ϕ3\gamma/\phi_3 with BB decays. Using our results, the decay model sensitivity to the γ/ϕ3\gamma/\phi_3 measurement is expected to be between 0.7^{\circ} and 1.2^{\circ}, approximately a factor of three smaller than that achievable with previous measurements. The improved precision of this work ensures that measurements of γ/ϕ3\gamma/\phi_3 will not be limited by knowledge of strong phases for the next decade. Furthermore, our results provide critical input for other flavor-physics investigations, including charm mixing, other measurements of CPCP violation, and the measurement of strong-phase parameters for other DD-decay modes.
By analyzing 2.93 fb1^{-1} data collected at the center-of-mass energy s=3.773\sqrt s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+Kˉ0e+νeD^+\rightarrow\bar K^0 e^{+}\nu_{e} to be ${\mathcal B}(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e})=(8.59 \pm 0.14 \pm 0.21)\%using using \bar K^0\to K^0_S\to \pi^0\pi^0$, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.
Wuhan UniversityChinese Academy of Sciences logoChinese Academy of SciencesCarnegie Mellon University logoCarnegie Mellon UniversitySichuan UniversitySun Yat-Sen University logoSun Yat-Sen UniversityUniversity of Science and Technology of China logoUniversity of Science and Technology of ChinaBeihang University logoBeihang UniversityIndiana UniversityShanghai Jiao Tong University logoShanghai Jiao Tong UniversityNanjing University logoNanjing UniversityUniversity of TabukNankai UniversityDalian University of TechnologyPeking University logoPeking UniversityJoint Institute for Nuclear ResearchUniversity of Minnesota logoUniversity of MinnesotaSeoul National University logoSeoul National UniversityUppsala UniversityGuangxi Normal UniversityCentral China Normal UniversityShandong University logoShandong UniversityNovosibirsk State UniversityYunnan UniversityLanzhou UniversityUniversity of FerraraIndian Institute of Technology MadrasSoochow UniversityUniversity of South ChinaUniversity of JinanUniversity of TorinoNanjing Normal UniversityUniversity of South CarolinaGuangxi UniversityShanxi UniversityHenan University of Science and TechnologyInner Mongolia UniversityUniversity of PerugiaZhengzhou UniversityINFN, Sezione di TorinoINFN, Laboratori Nazionali di FrascatiJohannes Gutenberg University MainzHenan Normal UniversityAnkara UniversityChina University of Geosciences BeijingJustus Liebig University GiessenHangzhou Normal UniversityHelmholtz Institute MainzUniversity of the PunjabLiaoning UniversityHuazhong Agricultural UniversityUniversity of MuensterG.I. Budker Institute of Nuclear Physics SB RASDogus UniversityUniversity of Science and Technology LiaoningBeijing Institute of Petrochemical TechnologyKVI-CART, University of GroningenXinyang Normal UniversityCOMSATS Institute of Information TechnologyBochum Ruhr-UniversityGSI Helmholtzcentre for Heavy Ion Research GmbHKTO Karatay UniversityINFN-Sezione di Ferrara
Using the data sample of an integrated luminosity of 2.93 fb1^{-1} taken at the center-of-mass energy of 3.773 GeV, we search for the Majorana neutrino in the lepton number violating decays DKπe+e+D\to K \pi e^+ e^+. No significant signal is observed, and the upper limits on the branching fraction at the 90\% confidence level are set to be \mathcal{B}\,(D^0 \to K^- \pi^- e^+ e^+)<2.8\times10^{-6}, \mathcal{B}\,(D^+ \to K_S^0 \pi^- e^+ e^+)<3.3\times10^{-6} and \mathcal{B}\,(D^+ \to K^- \pi^0 e^+ e^+)<8.5\times10^{-6}. The Majorana neutrino is searched for with different mass assumptions ranging from 0.25 to 1.0 GeV/c2c^2 in the decays D0Ke+νN(πe+)D^0\to K^- e^+ \nu_N(\pi^- e^+) and D+KS0e+νN(πe+)D^+\to K_S^0 e^+ \nu_N(\pi^- e^+), and the upper limits on the branching fraction at the 90\% confidence level are extracted to be at the level of 10710610^{-7} \sim 10^{-6}, depending on the mass of Majorana neutrino. The constraints on the mixing matrix element VeN2|V_{eN}|^2 are also evaluated.
Wuhan UniversityChinese Academy of Sciences logoChinese Academy of SciencesCarnegie Mellon University logoCarnegie Mellon UniversitySichuan UniversitySun Yat-Sen University logoSun Yat-Sen UniversityUniversity of Oxford logoUniversity of OxfordFudan University logoFudan UniversityUniversity of Science and Technology of China logoUniversity of Science and Technology of ChinaBeihang University logoBeihang UniversityIndiana UniversityShanghai Jiao Tong University logoShanghai Jiao Tong UniversityNanjing University logoNanjing UniversityHunan Normal UniversityZhejiang University logoZhejiang UniversityNankai UniversityPeking University logoPeking UniversityJoint Institute for Nuclear ResearchUniversity of Minnesota logoUniversity of MinnesotaUppsala UniversitySoutheast UniversityUniversity of LiverpoolGuangxi Normal UniversityCentral China Normal UniversityShandong University logoShandong UniversityNovosibirsk State UniversityLanzhou UniversityIndian Institute of Technology MadrasSoochow UniversityUniversity of South ChinaUniversity of JinanMoscow Institute of Physics and TechnologyUniversity of TorinoNanjing Normal UniversityGuangxi UniversityShanxi UniversityHenan University of Science and TechnologyZhengzhou UniversityINFN, Sezione di TorinoCOMSATS University IslamabadINFN, Laboratori Nazionali di FrascatiJohannes Gutenberg University MainzHenan Normal UniversityAnkara UniversityUniversity of Hawai’iJustus Liebig University GiessenUniversity of the PunjabLiaoning UniversityShandong Normal UniversityHuazhong Agricultural UniversityUniversity of MuensterG.I. Budker Institute of Nuclear Physics SB RASHelmholtz-Institut MainzGazi UniversityBeijing Institute of Petrochemical TechnologyKVI-CART, University of GroningenUniversity of Engineering and Technology LahoreState Key Laboratory of Particle Detection and ElectronicsBochum Ruhr-UniversityGSI Helmholtzcentre for Heavy Ion Research GmbHMoscow Engineering Physics Institute (National Research Nuclear University)Goethe-University, FrankfurtINFN-Sezione di Ferrara
We study the e+eγωJ/ψe^+e^-\to\gamma\omega J/\psi process using 11.6 fb111.6 ~\rm fb^{-1} e+ee^+ e^- annihilation data taken at center-of-mass energies from s=4.008 GeV\sqrt{s}=4.008~\rm GeV to 4.600 GeV4.600~\rm GeV with the BESIII detector at the BEPCII storage ring. The X(3872)X(3872) resonance is observed for the first time in the ωJ/ψ\omega J/\psi system with a significance of more than 5σ5\sigma. The relative decay ratio of X(3872)ωJ/ψX(3872)\to\omega J/\psi and π+πJ/ψ\pi^+\pi^- J/\psi is measured to be R=1.60.3+0.4±0.2\mathcal{R}=1.6^{+0.4}_{-0.3}\pm0.2, where the first error is statistical and the second systematic (the same hereafter). The s\sqrt{s}-dependent cross section of e+eγX(3872)e^+e^-\to\gamma X(3872) is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the Y(4200)Y(4200), with a mass of 4200.613.3+7.9±3.0 MeV/c24200.6^{+7.9}_{-13.3}\pm3.0~{\rm MeV}/c^2 and a width of 11526+38±12 MeV115^{+38}_{-26}\pm12~{\rm MeV}. In addition, to describe the ωJ/ψ\omega J/\psi mass distribution above 3.9 GeV/c23.9~\rm GeV/c^2, we need at least one additional Breit-Wigner resonance, labeled as X(3915)X(3915), in the fit. The mass and width of the X(3915)X(3915) are measured to be 3926.4±2.2±1.2 MeV/c23926.4\pm2.2\pm1.2~\rm MeV/c^2 and 3.8±7.5±2.6 MeV3.8\pm7.5\pm2.6~\rm MeV, or 3932.6±8.7±4.7 MeV/c23932.6\pm8.7\pm4.7~\rm MeV/c^2 and 59.7±15.5±3.7 MeV59.7\pm15.5\pm3.7~\rm MeV, respectively, depending on the fit models. The resonant parameters of the X(3915)X(3915) agree with those of the Y(3940)Y(3940) in BKωJ/ψB\to K\omega J/\psi and of the X(3915)X(3915) in γγωJ/ψ\gamma\gamma\to\omega J/\psi by the Belle and BABAR experiments within errors.
We investigated precision measurements in a two-level system coupled to a single-photon-added coherent state (SPACS) under postselection measurement. We analyzed strategies for improving measurement precision, including parameter estimation and the signal-to-noise ratio (SNR) in postselected weak measurements using the photon statistics of SPACS as the meter. Our results demonstrate that SPACS-based postselected weak measurements can outperform conventional measurement schemes in terms of precision. Additionally, we explicitly introduced an alternative weak measurement method commonly applied in dispersive light-atom interactions. Our work offers a new way for addressing fundamental issues in quantum precision measurement based on photon statistics, and it provides a method for extracting the phase and phase shifts of radiation fields through the weak values of system observables.
Using 14.0 million ψ(2S)eventscollectedwiththeBESIIdetector,asearchforthedecayofthe\psi(2S) events collected with the BES-II detector, a search for the decay of the \jpsitoaninvisiblefinalstatein to an invisible final state in \psiptoisperformed.The is performed. The \jpsipeakinthedistributionofmassrecoilingagainstthe peak in the distribution of mass recoiling against the \pi^+\pi^-isusedtotag is used to tag \psiinvisibledecay.Nosignalisfound,andanupperlimitatthe90 invisible decay. No signal is found, and an upper limit at the 90% confidence level is determined to be 1.2\times 10^{-2}fortheratio for the ratio \frac{{\cal B}(\jpsi\ar {invisible})}{{\cal B}(\jpsi\ar\mu^+\mu^-)}.Thisisthefirstsearchfor. This is the first search for J/\psi$ decay to an invisible final state.
Circular dichroism (CD) caused by the response of a chiral object to circularly polarized light has been well established, and the strong CD of plasmonic meta-molecules has also become of interest in recent years; however, their response if the light also has orbital angular momentum is unclear. In this paper, the dichroism of a plasmonic cuboid-protuberance chiral structure under the illumination of a light beam with both orbital and spin angular momentums is numerically investigated. Distinguished spectra are observed under the different momentums. The circular dichroism under the combination of vortex beam and light spin is enhanced. This phenomenon is attributed to the partial spatial excitation of the nanoparticle, and the strong dichroism is simultaneously caused because of the interaction of the induced electric and magnetic modes and other higher-order modes caused by the partial excitation of the vortex beam. This research provides further insight into chiral light-matter interactions and the dichroism of light with orbital angular momentum.
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