We investigate the backscattering for converging beams in iron-doped lithium niobate crystals. Due to the nonlinear properties of the crystal, backscattering exhibits temporally fluctuating speckles that make a transi...We investigate the backscattering for converging beams in iron-doped lithium niobate crystals. Due to the nonlinear properties of the crystal, backscattering exhibits temporally fluctuating speckles that make a transition to the phase conjugate of the incident beam under certain circumstances. Our observation seems to point to a new kind of self-pumped phase conjugation in photorefractive media.展开更多
After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell i...After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell interaction and spin- flip hypotheses. The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorienta- tions, presumably from the spin-flips of central engines following the mergers of pairs of galaxies, each of which contains a supermassive black hole. We confront these models with a number of key observations, and thus argue that none of the models is capable of explaining the entire range of the salient observational properties of XRGs, although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable. We then propose a new scenario which also involves galac- tic mergers but would allow the spin of the central engine to maintain its direction. Motivated by detailed multi-band observations of the nearest radio galaxy, Centaurus A, this new model emphasizes the role of the interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets, occasionally giving rise to an X-shaped radio struc- ture. Although each model is likely to be relevant to a subset of XRGs, the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.展开更多
A new search for two-neutrino double-beta(2νββ)decay of^(136)Xe to the 0+1 excited state of 136Ba is performed with the full EXO-200 dataset.A deep learning-based convolutional neural network is used to discriminat...A new search for two-neutrino double-beta(2νββ)decay of^(136)Xe to the 0+1 excited state of 136Ba is performed with the full EXO-200 dataset.A deep learning-based convolutional neural network is used to discriminate signal from background events.Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two.With the addition of the Phase II dataset taken with an upgraded detector,the median 90%confidence level half-life sensitivity of 2νββdecay to the 0+1 state of 136Ba is 2.9×10^(24)yr using a total^(136)Xe exposure of 234.1 kg yr.No statistically significant evidence for 2νββdecay to the 0^(+)_(1)state is observed,leading to a lower limit of T2ν1/2(0^(+)→0^(+)_(1))>1.4×10^(24)yr at 90%confidence level,improved by 70%relative to the current world's best constraint.展开更多
In a spin-driven multiferroic system,the magnetoelectric coupling has the form of effective dynamical Dzyaloshinskii–Moriya(DM)interaction.Experimentally,it is confirmed,for instance,for Cu_(2)OSeO_(3),that the DM in...In a spin-driven multiferroic system,the magnetoelectric coupling has the form of effective dynamical Dzyaloshinskii–Moriya(DM)interaction.Experimentally,it is confirmed,for instance,for Cu_(2)OSeO_(3),that the DM interaction has an essential role in the formation of skyrmions,which are topologically protected magnetic structures.Those skyrmions are very robust and can be manipulated through an electric field.The external electric field couples to the spin-driven ferroelectric polarization and the skyrmionic magnetic texture emerged due to the DM interaction.In this work,we demonstrate the effect of optical tweezing.For a particular configuration of the external electric fields it is possible to trap or release the skyrmions in a highly controlled manner.The functionality of the proposed tweezer is visualized by micromagnetic simulations and model analysis.展开更多
Using the vector exchange interaction in the local hidden gauge approach,which in the light quark sector generates the chiral Lagrangians and has produced realistic results for Ωc,Ξc,Ξb and the hidden charm pentaqu...Using the vector exchange interaction in the local hidden gauge approach,which in the light quark sector generates the chiral Lagrangians and has produced realistic results for Ωc,Ξc,Ξb and the hidden charm pentaquark states,we study the meson-baryon interactions in the coupled channels that lead to the Ξbb and Ωbbb excited states of the molecular type.We obtain seven states of the Ξbb type with energies between 10408 and 10869 MeV,and one Ωbbb state at 15212 MeV.展开更多
基金Supported by the Excellent Young Teachers Programme of the Ministry of Education of China under Grant No 2002-350, the National Natural Science Foundation of China under Grant No 60208003, the Key Scientific and Technical Innovation Project of the Ministry of Education of China （704012）, the Programme for Changjiang Scholars and Innovative Research Team in University and the Start-up Research Foundation of Nankai University （J02020）.
文摘We investigate the backscattering for converging beams in iron-doped lithium niobate crystals. Due to the nonlinear properties of the crystal, backscattering exhibits temporally fluctuating speckles that make a transition to the phase conjugate of the incident beam under certain circumstances. Our observation seems to point to a new kind of self-pumped phase conjugation in photorefractive media.
文摘After a brief, critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology （XRGs） we propose a generalized model, based on the jet-shell interaction and spin- flip hypotheses. The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorienta- tions, presumably from the spin-flips of central engines following the mergers of pairs of galaxies, each of which contains a supermassive black hole. We confront these models with a number of key observations, and thus argue that none of the models is capable of explaining the entire range of the salient observational properties of XRGs, although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable. We then propose a new scenario which also involves galac- tic mergers but would allow the spin of the central engine to maintain its direction. Motivated by detailed multi-band observations of the nearest radio galaxy, Centaurus A, this new model emphasizes the role of the interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets, occasionally giving rise to an X-shaped radio struc- ture. Although each model is likely to be relevant to a subset of XRGs, the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.
文摘A new search for two-neutrino double-beta(2νββ)decay of^(136)Xe to the 0+1 excited state of 136Ba is performed with the full EXO-200 dataset.A deep learning-based convolutional neural network is used to discriminate signal from background events.Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two.With the addition of the Phase II dataset taken with an upgraded detector,the median 90%confidence level half-life sensitivity of 2νββdecay to the 0+1 state of 136Ba is 2.9×10^(24)yr using a total^(136)Xe exposure of 234.1 kg yr.No statistically significant evidence for 2νββdecay to the 0^(+)_(1)state is observed,leading to a lower limit of T2ν1/2(0^(+)→0^(+)_(1))>1.4×10^(24)yr at 90%confidence level,improved by 70%relative to the current world's best constraint.
基金This work was supported by the National Science Center in Poland as a research Project No.DEC-2017/27/B/ST3/02881by the DFG through the SFB 762 and SFB-TRR227+5 种基金by the National Natural Science Foundation of China No.11704415,024410-7the Natural Science Foundation of Hunan Province of China No.2018JJ3629A.E.acknowledges financial support from DFG through priority program SPP1666(Topological Insulators)SFB-TRR227,and OeAD Grants Nos.HR 07/2018 and PL 03/2018This work was supported by Shota Rustaveli National Science Foundation of Georgia(SRNSFG)[Grant No.FR-19-4049]Open access funding provided by Projekt DEAL.
文摘In a spin-driven multiferroic system,the magnetoelectric coupling has the form of effective dynamical Dzyaloshinskii–Moriya(DM)interaction.Experimentally,it is confirmed,for instance,for Cu_(2)OSeO_(3),that the DM interaction has an essential role in the formation of skyrmions,which are topologically protected magnetic structures.Those skyrmions are very robust and can be manipulated through an electric field.The external electric field couples to the spin-driven ferroelectric polarization and the skyrmionic magnetic texture emerged due to the DM interaction.In this work,we demonstrate the effect of optical tweezing.For a particular configuration of the external electric fields it is possible to trap or release the skyrmions in a highly controlled manner.The functionality of the proposed tweezer is visualized by micromagnetic simulations and model analysis.
基金Partly supported by the National Natural Science Foundation of China (11975083, 11947413, 11847317, 11565007, 11735003, 1191101015)the support from the National Natural Science Foundation of China (11775024, 11575023, 11805153)+3 种基金China Scholarship CouncilPartly supported by the Spanish Ministerio de Economia y Competitividad and European FEDER funds (FIS2017-84038-C2-1-PB,FIS2017-84038-C2-2-PB)the Generalitat Valenciana in the program Prometeo II-2014/068the project Severo Ochoa of IFIC, SEV-2014-0398
文摘Using the vector exchange interaction in the local hidden gauge approach,which in the light quark sector generates the chiral Lagrangians and has produced realistic results for Ωc,Ξc,Ξb and the hidden charm pentaquark states,we study the meson-baryon interactions in the coupled channels that lead to the Ξbb and Ωbbb excited states of the molecular type.We obtain seven states of the Ξbb type with energies between 10408 and 10869 MeV,and one Ωbbb state at 15212 MeV.
