Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-...Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-visiting original Feynman picture of a hadron moving at asymptotically large momentum.Here I formulate the approach in the language of an effective field theory for a large hadron momentum P in lattice QCD,LaMET for short.I show that using this new effective theory,parton properties,including light-front parton wave functions,can be extracted from lattice observables in a systematic expansion of 1/P,much like that the parton distributions can be extracted from the hard scattering data at momentum scales of a few GeV.展开更多
We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of t...We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by Te.However,the band gap between the electron-and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted by theoretical calculations.Our results provide a clear experimental indication that the FeTe_(1-x)Se_x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically.展开更多
Traditional exhaustive extraction methods often overestimate the risk of polycyclic aromatic hydrocarbon(PAH) bioaccessibility to biota. Therefore, reliable assessment methods need to be established. In this study, a ...Traditional exhaustive extraction methods often overestimate the risk of polycyclic aromatic hydrocarbon(PAH) bioaccessibility to biota. Therefore, reliable assessment methods need to be established. In this study, a composite extraction with hydroxypropyl-β-cyclodextrin(HPCD) and three low-molecular-weight organic acids, oxalic acid(OA), malic acid(MA), and citric acid(CA), was used to predict the PAH bioaccessibility to earthworms, subjecting to two soils(red soil and yellow soil) spiked with selected PAHs,phenanthrene, pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene. For both soils,concentrations of PAHs by composite extraction using HPCD-OA(R^2= 0.89–0.92, slope = 1.89–2.03; n = 35), HPCD-MA(R^2=0.92–0.96, slope = 1.43–1.67; n = 35), and HPCD-CA(R^2= 0.92–0.96, slope = 1.26–1.56; n = 35) were significantly correlated with PAH accumulation in the Eisenia fetida earthworms. Moreover, the HPCD-CA-and HPCD-MA-extracted PAH concentrations were closer to the earthworm-accumulated PAH concentration than the extraction using just HPCD. The results indicated that the composite extraction could improve the prediction of PAH bioaccessibility, and therefore can serve as a reliable chemical method to predict PAH bioaccessibility to earthworms in contaminated soils.展开更多
The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in ...The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in the photon energy region of 2900（P40000 cm^-1 at experimental bandwidth of -0.1 cm-1. The excitation spectra of the even-parity autoionizing resonance series, most of which are experimentally studied for the first time in this work, show typical asymmetric line shapes. Complementary information on level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the auto- ionizing resonances are derived by Fano-type line-shape analyses of the experimental results. Results from this work indicate that the line profile index （q） and the resonance width （F） are approximately proportional to the effective principal quantum number （n＊）; the line separation of the 4p^5np＇ autoionizing resonances is also in good agreement with theoretical model展开更多
基金partially supported by the U.S.Department of Energy(Grant No.DE-FG02-93ER-40762)the Office of Science and Technology in Shanghai Municipal Government(Grant No.11DZ2260700)the National Natural Science Foundation of China(Grant No.11175114)
文摘Parton physics,when formulated as light-front correlations,are difficult to study non-perturbatively,despite the promise of lightfront quantization.Recently an alternative approach to partons have been proposed by re-visiting original Feynman picture of a hadron moving at asymptotically large momentum.Here I formulate the approach in the language of an effective field theory for a large hadron momentum P in lattice QCD,LaMET for short.I show that using this new effective theory,parton properties,including light-front parton wave functions,can be extracted from lattice observables in a systematic expansion of 1/P,much like that the parton distributions can be extracted from the hard scattering data at momentum scales of a few GeV.
基金supported by grants from the Ministry of Science and Technology of China(2015CB921000,2016YFA0401000,2015CB921301,2016YFA0300300)the National Natural Science Foundation of China(11574371,11274362,1190020,11334012,11274381,11674371)
文摘We performed angle-resolved photoemission spectroscopy studies on a series of FeTe_(1-x)Se_x monolayer films grown on Sr TiO_3.The superconductivity of the films is robust and rather insensitive to the variations of the band position and effective mass caused by the substitution of Se by Te.However,the band gap between the electron-and hole-like bands at the Brillouin zone center decreases towards band inversion and parity exchange,which drive the system to a nontrivial topological state predicted by theoretical calculations.Our results provide a clear experimental indication that the FeTe_(1-x)Se_x monolayer materials are high-temperature connate topological superconductors in which band topology and superconductivity are integrated intrinsically.
基金supported by the National Key Basic Research Development Program (973) (No. 2014CB441105)the National Natural Science Foundation of China (Nos. 41271327, 41271464 and 21377138)
文摘Traditional exhaustive extraction methods often overestimate the risk of polycyclic aromatic hydrocarbon(PAH) bioaccessibility to biota. Therefore, reliable assessment methods need to be established. In this study, a composite extraction with hydroxypropyl-β-cyclodextrin(HPCD) and three low-molecular-weight organic acids, oxalic acid(OA), malic acid(MA), and citric acid(CA), was used to predict the PAH bioaccessibility to earthworms, subjecting to two soils(red soil and yellow soil) spiked with selected PAHs,phenanthrene, pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene. For both soils,concentrations of PAHs by composite extraction using HPCD-OA(R^2= 0.89–0.92, slope = 1.89–2.03; n = 35), HPCD-MA(R^2=0.92–0.96, slope = 1.43–1.67; n = 35), and HPCD-CA(R^2= 0.92–0.96, slope = 1.26–1.56; n = 35) were significantly correlated with PAH accumulation in the Eisenia fetida earthworms. Moreover, the HPCD-CA-and HPCD-MA-extracted PAH concentrations were closer to the earthworm-accumulated PAH concentration than the extraction using just HPCD. The results indicated that the composite extraction could improve the prediction of PAH bioaccessibility, and therefore can serve as a reliable chemical method to predict PAH bioaccessibility to earthworms in contaminated soils.
基金financially supported by the National Natural Science Foundation of China(51007092)
文摘The even-parity autoionizing resonance series 4p^5np＇ [3/2] 1,2, [ 1/2] 1, and 4p^2nf＇ [5/213 of krytpon have been investigated by laser excitation from the two metastable states 4p55s [3/2]2 and 4p^55s＇ [1/2]0 in the photon energy region of 2900（P40000 cm^-1 at experimental bandwidth of -0.1 cm-1. The excitation spectra of the even-parity autoionizing resonance series, most of which are experimentally studied for the first time in this work, show typical asymmetric line shapes. Complementary information on level energies, quantum defects, line profile indices and resonance widths, resonance lifetimes and reduced widths of the auto- ionizing resonances are derived by Fano-type line-shape analyses of the experimental results. Results from this work indicate that the line profile index （q） and the resonance width （F） are approximately proportional to the effective principal quantum number （n＊）; the line separation of the 4p^5np＇ autoionizing resonances is also in good agreement with theoretical model
