Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms ...Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms in consolidation is of great engineering significance.We conduct non-equilibrium molecular dynamics(NEMD)simulation and X-ray diffraction(XRD)simulation to systematically study shock-induced deformation and the corresponding mechanisms during the consolidation of nanopowdered Mg(NP-Mg).Two different deformation modes govern the shock consolidation in NP-Mg,i.e.,deformation twinning at up≤1.5 km s^(-1)and structural disordering,at up≥2.0 km s^(-1).They accelerate the collapse of nanopores and void compaction,giving rise to the final consolidation of NP-Mg.Three types of deformation twinning are emitted in NP-Mg,i.e.,the extension twinning for{1121}(1126),and{1102}〈1101>,and the compression{1122}(1123)twinning.They are prompted via coupling atomic shuffles and slips.Deformation twinning prefers to occur within the grains as shock along<1120>or its approaching direction(A-and B-type grains),originated from the high-angle grain boundaries(HAGB)at compression stage.They are inhibited within the ones as shocking along<0001>and the approaching ones(C-and D-type grains).The release and tension loading facilitates the reversible and irreversible detwinning,for the extension and compression twinning,respectively,within the A-and B-type grains.It also contributes to a compression-tension asymmetry for twinning,i.e.,release and tension induced extension twinning within the C-and D-type grains.The subsequent spallation is mediated by GB sliding and GB-induced stacking faults at up≤1.5 km s^(-1),and structural disordering at up≥2.0 km s^(-1).展开更多
In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-si...In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-side FSW butt joint with more attention paid to the local characteristic zones.It was shown that a phenomenon of microstructural inhomogeneity existed in the nugget zone(NZ)through the thickness direction.The grain size presented an obvious gradient distribution from the top to the bottom for each single-pass weld,and the microhardness values decreased from both surfaces to the middle of the NZ.The lowest hardness zone(LHZ)exhibited a"hyperbolical"-shaped distribution extending to the middle of the NZ.Similar tensile properties were obtained in the three sliced specimens of the FSW joint,and the joint coefficient reached about 70%which achieved the same level as the conventional FSW Al alloy joints.Finite element modeling proved that the"hyperbolical"-shaped heat affected zone(HAZ)was beneficial to resisting the strain concentration in the middle layer specimen which helped to increase the tensile strength.Based on the analysis of the hardness contour map,tensile property and microstructural evolution of the joints,an Isothermal Softening Layer(ISL)model was proposed and established,which may have a helpful guidance for the optimization on the FSW of ultra-thick Al alloy plates.展开更多
Guided waves in the multilayered one-dimensional quasi-crystal plates are,respectively,investigated in the context of the Bak and elasto-hydrodynamic models.Dispersion curves and phonon and phason displacements are ca...Guided waves in the multilayered one-dimensional quasi-crystal plates are,respectively,investigated in the context of the Bak and elasto-hydrodynamic models.Dispersion curves and phonon and phason displacements are calculated using the Legendre polynomial method.Wave characteristics in the context of these two models are analyzed in detail.Results show that the phonon-phason coupling effects on the first two layers are the same at low frequencies;but,they are more significant on the first layer than those on the second layer at high frequencies.These obtained results lay the theoretical basis of guided-wave nondestructive test on multilayered quasi-crystal plates.展开更多
Using inclusive decays of J/ψ aprecise determination of the number of J/ψ events collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψ events were recalcul...Using inclusive decays of J/ψ aprecise determination of the number of J/ψ events collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψ events were recalculated to be(224.0±1.3)×10^(6) and(1088.5±4.4)×10^(6),respectively;these numbers are in good agreement with the previous measurements. For the J/ψ sample taken in 2017-2019,the number of events was determined to be(8774.0±39.4)×10^(6).The total number of J/ψ events collected with the BESIII detector was determined to be(10087±44)×10^(6),where the uncertainty is dominated by systematic effects,and the statistical uncertainty is negligible.展开更多
By analyzing ψ(3686) data sample containing (107.7±0.6)×10^(6) events taken with the BESIII detector at the BEPCII storage ring in 2009,the χ_(c 0) resonance parameters are precisely measured using χ_(c 0...By analyzing ψ(3686) data sample containing (107.7±0.6)×10^(6) events taken with the BESIII detector at the BEPCII storage ring in 2009,the χ_(c 0) resonance parameters are precisely measured using χ_(c 0,c 2)→π^(+)π^(−)/K^(+)K^(−) events.The mass of χ_(c 0) is determined to be M (χ_(c 0))=(3415.63±0.07±0.07±0.07)MeV/c^(2),and its full width is F (χ_(c 0))=(12.52±0.12±0.13)MeV,where the first uncertainty is statistical,the second systematic,and the third for mass comes from χ_(c 2) mass uncertainty.These measurements improve the precision of χ_(c 0) mass by a factor of four and width by one order of magnitude over the previous individual measurements,and significantly boost our knowledge about the charmonium spectrum.Together with additional (345.4±2.6)×10^(6)(3686) data events taken in 2012,the decay branching fractions of χ_(c 0,c 2)→π^(+)π^(−)/K^(+)K^(−) are measured as well,with precision improved by a factor of three compared to previous measurements.These χ_(c 0) decay branching fractions provide important inputs for the study of glueballs.展开更多
Using 20.3 fb^(-1)of e^(+)e^(-)annihilation data collected at a center-of-mass energy of 3.773 GeV with the BESⅢdetector,we report on an improved search for the radiative leptonic decay D^(+)→γe^(+)ve.An upper limi...Using 20.3 fb^(-1)of e^(+)e^(-)annihilation data collected at a center-of-mass energy of 3.773 GeV with the BESⅢdetector,we report on an improved search for the radiative leptonic decay D^(+)→γe^(+)ve.An upper limit on its partial branching fraction for photon energies E_(γ)>10 MeV was determined to be 1.2×10^(-5)at a 90%confidence level;this excludes most current theoretical predictions.A sophisticated deep learning approach,which includes thorough validation and is based on the Transformer architecture,was implemented to efficiently distinguish the signal from massive backgrounds.展开更多
Using an electron-positron collision data sample corresponding to(1.0087±0.0044)×10^(10)events collected using the BESIII detector at the BEPCII collider,we firstly search for the lepton number violation de...Using an electron-positron collision data sample corresponding to(1.0087±0.0044)×10^(10)events collected using the BESIII detector at the BEPCII collider,we firstly search for the lepton number violation decayφ→π^(+)π^(+)e^(-)e^(-)via J/ψ→φη.No obviously signals are found.The upper limit on the branching fraction ofφ→π^(+)π^(+)e^(-)e^(-)is set to be 1.3×10^(-5)at the 90%confidence level.展开更多
Lepton number violation decayω→π^(+)π^(+)e^(-)e^(-)+c.c.is searched for via J/ψ→ωηusing a data sample of(1.0087±0.0044)×10^(10)J/ψevents collected via the BESIII detector at the BEPCII collider.No s...Lepton number violation decayω→π^(+)π^(+)e^(-)e^(-)+c.c.is searched for via J/ψ→ωηusing a data sample of(1.0087±0.0044)×10^(10)J/ψevents collected via the BESIII detector at the BEPCII collider.No significant signal is observed,and the upper limit on the branching fraction ofω→π^(+)π^(+)e^(-)e^(-)+c.c.at the 90%confidence level is determined for the first time to be 2.8×10^(-6).展开更多
We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant si...We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant signal is not observed,and an upper limit on the branching fraction of D^(+)→e^(+)ν_(e)is set as 9.7×10^(-7),at a confidence level of 90%.Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.展开更多
Utilizing 4.5 fb^(-1)ofe^(+)e^(-)annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider,we searched for singly Cabibbo-suppressed h...Utilizing 4.5 fb^(-1)ofe^(+)e^(-)annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider,we searched for singly Cabibbo-suppressed hadronic decaysΛ_(c)^(+)→Σ^(0)K^(+)π^(0)andΛ_(c)^(+)→Σ^(0)K^(+)π^(+)π^(−)and with a single-tag method.No significant signals were observed for both decays.The upper limits on the branching fractions at the 90%confidence level were determined to be 5.0×10^(-4)for and forΛ_(c)^(+)→Σ^(0)K^(+)π^(0)and 6.5×10^(-4)forΛ_(c)^(+)→Σ^(0)K^(+)π^(+)π^(−).展开更多
Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb^(-1),th...Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb^(-1),the process e^(+)e^(-)→pppñπ+c.c.is observed for the first time with a statistical significance of 11.5σ.The average Born cross sections in the energy ranges of(4.160,4.380)GeV,(4.400,4.600)GeV and(4.610,4.700)GeV are measured to be(21.5±5.7±1.2)fb,(46.3±10.6±2.5)fb and(59.0±9.4±3.2)fb,respectively,where the first uncertainties are statistical and the second are systematic.The line shapes of the pñ and ppπ^(-)invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.展开更多
We report a search for a heavier partner of the recently observed Z_(cs)(3985)^(-) state,denoted as Z_(cs)^('-),in the process e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.,based on e^(*)e^(-)collision data collected ...We report a search for a heavier partner of the recently observed Z_(cs)(3985)^(-) state,denoted as Z_(cs)^('-),in the process e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.,based on e^(*)e^(-)collision data collected at the center-of-mass energies of √s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Z_(cs)^('-) is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K^(+)recoil-mass spectra,which are probed for a potential contribution from Z_(cs)^('-)→D_(s)^(∗−) D^(∗0 )+ c.c.We find an excess of Z_(cs)^('-)→D_(s)^(*-)-D^(*0)(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7_(sat)±4.7_(syst.))MeV/c^(2).As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σ^(Borm))and the branching fraction(B)of Z_(cs)^('-)→D_(s)^(*-)-D^(*0),under different assumptions of the Z_(cs)^('-) mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits of σ^(Born).B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Z_(cs)^('-) state and clarify its nature in the coming years.展开更多
The integrated luminosities of data samples collected in the BESⅢ experiment in 2016-2017 at centerof-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhab...The integrated luminosities of data samples collected in the BESⅢ experiment in 2016-2017 at centerof-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events.The integrated luminosities of old datasets collected in 2010-2014 are updated by considering corrections related to detector performance,offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter,which can haphazardly occur.展开更多
From December 2019 to June 2021,the BESⅢ experiment collected approximately 5.85 fb^(−1) of data at center-of-mass energies between 4.61 and 4.95 GeV.This is the highest collision energy BEPCⅡ has reached to date.Th...From December 2019 to June 2021,the BESⅢ experiment collected approximately 5.85 fb^(−1) of data at center-of-mass energies between 4.61 and 4.95 GeV.This is the highest collision energy BEPCⅡ has reached to date.The accumulated e^(+)e^(−) annihilation data samples are useful for studying charmonium(-like)states and charmed-hadron decays.By adopting a novel method of analyzing the production of A_(c)^(+)A_(c)^(-) pairs in e^(+)e^(−) annihilation,the center-of-mass energies are measured with a precision of 0.6 MeV.Integrated luminosities are measured with a precision of better than 1% by analyzing the events of large-angle Bhabha scattering.These measurements provide important inputs to analyses based on these data samples.展开更多
Using(448.1±2.9)×10^(6)ψ(3686)for the weak baryonic decayψ(3686)→Λc+∑-+c.c..The analysis procedure is optimized using a blinded method.No significant signal is observed,and the upper limit on the branch...Using(448.1±2.9)×10^(6)ψ(3686)for the weak baryonic decayψ(3686)→Λc+∑-+c.c..The analysis procedure is optimized using a blinded method.No significant signal is observed,and the upper limit on the branching fraction(B)ofψ(3686)→Λc+∑-+c.c.is set as 1.4×10^(-5)at the 90%confidence level.展开更多
Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first obser...Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛ_(c)^(+)→nπ^(+)π^(0),Λ_(c)^(+)→nπ^(+)π^(-)π^(+),and the Cabibbo-favored decayΛ_(c)^(+)→nK^(-)π^(+)π^(+)with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λ_(c)^(+)→nπ^(+)π^(0))=(0.64±0.09±0.02)%,B(Λ_(c)^(+)→nπ^(+)π^(-)π^(+))=(0.45±0.07±0.03)%,and B(Λ_(c)^(+)→nK^(-)π^(+)π^(+))=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛ_(c)^(+)→nπ^(+)π^(0)is about one order of magnitude higher than that ofΛ_(c)^(+)→nπ^(+).展开更多
The cross sections of e^(+)e^(-)→K^(+)K^(-)J/Ψat center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb-1data collected with the BESⅢ detector operating at the BEPCⅡ storage ring.Two resonan...The cross sections of e^(+)e^(-)→K^(+)K^(-)J/Ψat center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb-1data collected with the BESⅢ detector operating at the BEPCⅡ storage ring.Two resonant structures are observed in the line shape of the cross sections.The mass and width of the first structure are measured to be(4225.3±2.3±21.5)MeV and(72.9±6.1±30.8)MeV,respectively.They are consistent with those of the established Y(4230).The second structure is observed for the first time with a statistical significance greater than 8σ,denoted as Y(4500).Its mass and width are determined to be(4484.7±13.3±24.1)MeV and(111.1±30.1±15.2)MeV,respectively.The first presented uncertainties are statistical and the second ones are systematic.The product of the electronic partial width with the decay branching fractionΓ(Y(4230)→e^(+)e^(−))B(Y(4230)→K^(+)K^(−)J/Ψ)is reported.展开更多
The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that t...The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.展开更多
With the increasing application of steroid drugs as therapeutics,the demand for steroid drugs is increasing.In recent years,biological synthesis has become the standard approach to produce steroid intermediates,while ...With the increasing application of steroid drugs as therapeutics,the demand for steroid drugs is increasing.In recent years,biological synthesis has become the standard approach to produce steroid intermediates,while this method still faces some problems such as unclear metabolic pathway and low yield.Mycobacterium sp.LY-1 can convert phytosterols into 9α-hydroxyandrost-4-ene-3,17-dione(9α-OH-AD)which is a key intermediate for the synthesis of steroid drugs with long effective time and significant pharmacological activity.In this work,the whole-genome sequence of the Mycobacterium sp.LY-1 was analyzed,and the side-chain degradation pathway of phytosterols in Mycobacterium sp.LY-1 was proposed.Meanwhile,the related key enzymes of phytosterol metabolism were identified through qRT-PCR.Through overexpressing the key enzymes including KshA2,KshB,and HsdB,the yield of 9α-OH-AD increased by 12.7%compared to that of the control.Furthermore,by optimizing the medium and culture conditions,the yield of 9α-OH-AD reached 50.4%.The maxi-mum yield was 30.7%higher than that of the original strain.The results are of significance for the industrial production of 9α-OH-AD using metabolic engineering methods.展开更多
Using e^(+)e^(−)annihilation data corresponding to an integrated luminosity of 2.93 fb^(−1)taken at the center-of-mass energy√s=3.773 GeV with the BESIII detector,a joint amplitude analysis is performed on the decays...Using e^(+)e^(−)annihilation data corresponding to an integrated luminosity of 2.93 fb^(−1)taken at the center-of-mass energy√s=3.773 GeV with the BESIII detector,a joint amplitude analysis is performed on the decays D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η).The fit fractions of individual components are obtained,and large interferences among the dominant components of the decays D^(0)→a_(1)(1260)π,D^(0)→π(1300)π,D^(0)→ρ(770)ρ(770),and D^(0)→2(ππ)_(S)are observed in both channels.With the obtained amplitude model,the CP-even fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are determined to be(75.2±1.1_(stat).±1.5_(syst.))%and(68.9±1.5_(stat).±2.4_(syst.))%,respectively.The branching fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are measured to be(0.688±0.010_(stat.)±0.010_(syst.))%and(0.951±0.025_(stat.)±0.021_(syst.))%,respectively.The amplitude analysis provides an important model for the binning strategy in measuring the strong phase parameters of D^(0)→4πwhen used to determine the CKM angleγ(ϕ_(3))via the B^(−)→DK^(−)decay.展开更多
基金financially supported by the Natural Science Foundation(NSF)of China(Nos.11802092 and U2230401)NSF of Hunan Province(Nos.2019JJ50221,2019JJ40127,2020JJ5260,and 2020JJ4375)+5 种基金the Funding of the Hunan Education Department Project(Nos.20A248 and 22B0225)the Double first-class construction project of Hunan Agricultural University(No.SYL2019063)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20230682)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20230682)the Postgraduate Scientific Research Innovation Project of Hunan Agricultural University(No.2023XC019)We also acknowledge the support of the computation platform of the National Super Computer Center in Changsha(NSCC).
文摘Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials,and a thorough investigation of the deformation and its underlying mechanisms in consolidation is of great engineering significance.We conduct non-equilibrium molecular dynamics(NEMD)simulation and X-ray diffraction(XRD)simulation to systematically study shock-induced deformation and the corresponding mechanisms during the consolidation of nanopowdered Mg(NP-Mg).Two different deformation modes govern the shock consolidation in NP-Mg,i.e.,deformation twinning at up≤1.5 km s^(-1)and structural disordering,at up≥2.0 km s^(-1).They accelerate the collapse of nanopores and void compaction,giving rise to the final consolidation of NP-Mg.Three types of deformation twinning are emitted in NP-Mg,i.e.,the extension twinning for{1121}(1126),and{1102}〈1101>,and the compression{1122}(1123)twinning.They are prompted via coupling atomic shuffles and slips.Deformation twinning prefers to occur within the grains as shock along<1120>or its approaching direction(A-and B-type grains),originated from the high-angle grain boundaries(HAGB)at compression stage.They are inhibited within the ones as shocking along<0001>and the approaching ones(C-and D-type grains).The release and tension loading facilitates the reversible and irreversible detwinning,for the extension and compression twinning,respectively,within the A-and B-type grains.It also contributes to a compression-tension asymmetry for twinning,i.e.,release and tension induced extension twinning within the C-and D-type grains.The subsequent spallation is mediated by GB sliding and GB-induced stacking faults at up≤1.5 km s^(-1),and structural disordering at up≥2.0 km s^(-1).
基金supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences(2017236)National Natural Science Foundation of China under grant No.U1760201.
文摘In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-side FSW butt joint with more attention paid to the local characteristic zones.It was shown that a phenomenon of microstructural inhomogeneity existed in the nugget zone(NZ)through the thickness direction.The grain size presented an obvious gradient distribution from the top to the bottom for each single-pass weld,and the microhardness values decreased from both surfaces to the middle of the NZ.The lowest hardness zone(LHZ)exhibited a"hyperbolical"-shaped distribution extending to the middle of the NZ.Similar tensile properties were obtained in the three sliced specimens of the FSW joint,and the joint coefficient reached about 70%which achieved the same level as the conventional FSW Al alloy joints.Finite element modeling proved that the"hyperbolical"-shaped heat affected zone(HAZ)was beneficial to resisting the strain concentration in the middle layer specimen which helped to increase the tensile strength.Based on the analysis of the hardness contour map,tensile property and microstructural evolution of the joints,an Isothermal Softening Layer(ISL)model was proposed and established,which may have a helpful guidance for the optimization on the FSW of ultra-thick Al alloy plates.
基金The authors gratefully acknowledge the support by the National Natural Science Foundation of China(No.U1804134 and No.51975189)the Program for Innovative Research Team of Henan Polytechnic University(No.T2017-3)the Key Scientific and Technological Project of Henan Province(Nos.192102210189 and 182102210314).
文摘Guided waves in the multilayered one-dimensional quasi-crystal plates are,respectively,investigated in the context of the Bak and elasto-hydrodynamic models.Dispersion curves and phonon and phason displacements are calculated using the Legendre polynomial method.Wave characteristics in the context of these two models are analyzed in detail.Results show that the phonon-phason coupling effects on the first two layers are the same at low frequencies;but,they are more significant on the first layer than those on the second layer at high frequencies.These obtained results lay the theoretical basis of guided-wave nondestructive test on multilayered quasi-crystal plates.
基金Supported in part by National Key R&D Program of China(2020YFA0406300, 2020YFA0406400)National Natural Science Foundation of China(NSFC)(11625523, 11635010, 11735014, 11822506, 11835012, 11935015, 11935016, 11935018, 11961141012, 12022510, 12025502, 12035009, 12035013,12061131003,12075252)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263, U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union Horizon 2020 research and innovation programme Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(443159800), Collaborative Research Center CRC 1044, FOR 2359, GRK 214Istituto Nazionale di Fisica Nucleare, ItalyMinistry of Development of Turkey under Contract No. DPT2006K-120470National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society, UK(DH140054, DH160214)The Swedish Research CouncilU. S. Department of Energy(DE-FG02-05ER41374, DE-SC-0012069)
文摘Using inclusive decays of J/ψ aprecise determination of the number of J/ψ events collected with the BESIII detector was performed.For the two data sets taken in 2009 and 2012,the numbers of J/ψ events were recalculated to be(224.0±1.3)×10^(6) and(1088.5±4.4)×10^(6),respectively;these numbers are in good agreement with the previous measurements. For the J/ψ sample taken in 2017-2019,the number of events was determined to be(8774.0±39.4)×10^(6).The total number of J/ψ events collected with the BESIII detector was determined to be(10087±44)×10^(6),where the uncertainty is dominated by systematic effects,and the statistical uncertainty is negligible.
基金Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400,2023YFA1606000)National Natural Science Foundation of China(NSFC)(11635010,11735014,11935015,11935016,11935018,12025502,12035009,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+17 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)100 Talents Program of CAS(ZR2022JQ02,ZR2024QA151)supported by Shandong Provincial Natural Science Foundationsupported by the China Postdoctoral Science Foundation(2023M742100)The Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(FOR5327,GRK 2149)Istituto Nazionale di Fisica Nucleare,ItalyKnut and Alice Wallenberg Foundation(2021.0174,2021.0299)Ministry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF-2022R1A2C1092335)National Science and Technology fund of MongoliaNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation of Thailand(B16F640076,B50G670107)Polish National Science Centre(2019/35/O/ST2/02907)Swedish Research Council(2019.04595)The Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)U.S.Department of Energy(DE-FG02-05ER41374)。
文摘By analyzing ψ(3686) data sample containing (107.7±0.6)×10^(6) events taken with the BESIII detector at the BEPCII storage ring in 2009,the χ_(c 0) resonance parameters are precisely measured using χ_(c 0,c 2)→π^(+)π^(−)/K^(+)K^(−) events.The mass of χ_(c 0) is determined to be M (χ_(c 0))=(3415.63±0.07±0.07±0.07)MeV/c^(2),and its full width is F (χ_(c 0))=(12.52±0.12±0.13)MeV,where the first uncertainty is statistical,the second systematic,and the third for mass comes from χ_(c 2) mass uncertainty.These measurements improve the precision of χ_(c 0) mass by a factor of four and width by one order of magnitude over the previous individual measurements,and significantly boost our knowledge about the charmonium spectrum.Together with additional (345.4±2.6)×10^(6)(3686) data events taken in 2012,the decay branching fractions of χ_(c 0,c 2)→π^(+)π^(−)/K^(+)K^(−) are measured as well,with precision improved by a factor of three compared to previous measurements.These χ_(c 0) decay branching fractions provide important inputs for the study of glueballs.
基金supported in part by National Key R&D Program of China(2020YFA0406400,2023YFA1606000,2020YFA0406300)National Natural Science Foundation of China(NSFC)(11635010,11735014,11935015,11935016,11935018,12025502,12035009,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+18 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)CAS(YSBR-101)100 Talents Program of CASCAS Project for Young Scientists in Basic Research(YSBR-117)The Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyAgencia Nacional de Investigación y Desarrollo de Chile(ANID),Chile(ANID PIA/APOYO AFB230003)German Research Foundation DFG(FOR5327)Istituto Nazionale di Fisica Nucleare,ItalyKnut and Alice Wallenberg Foundation(2021.0174,2021.0299)Ministry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF-2022R1A2C1092335)National Science and Technology fund of MongoliaNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation of Thailand(B50G670107)Polish National Science Centre(2019/35/O/ST2/02907)Swedish Research Council(2019.04595)The Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)U.S.Department of Energy(DE-FG02-05ER41374)。
文摘Using 20.3 fb^(-1)of e^(+)e^(-)annihilation data collected at a center-of-mass energy of 3.773 GeV with the BESⅢdetector,we report on an improved search for the radiative leptonic decay D^(+)→γe^(+)ve.An upper limit on its partial branching fraction for photon energies E_(γ)>10 MeV was determined to be 1.2×10^(-5)at a 90%confidence level;this excludes most current theoretical predictions.A sophisticated deep learning approach,which includes thorough validation and is based on the Transformer architecture,was implemented to efficiently distinguish the signal from massive backgrounds.
基金supported in part by the National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(12035009,11635010,11735014,11835012,11935015,11935016,11935018,11961141012,12025502,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017)+17 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASthe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and Cosmologythe European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement(894790)the German Research Foundation DFG(455635585),the Collaborative Research Center CRC 1044,FOR5327,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyKnut and Alice Wallenberg Foundation(2021.0174,2021.0299)Ministry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF2022R1A2C1092335)National Science and Technology Fund of MongoliaNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation of Thailand(B16F640076)Polish National Science Centre(2019/35/O/ST2/02907)Swedish Research Council(2019.04595)the Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)the U.S.Department of Energy(DE-FG02-05ER41374).
文摘Using an electron-positron collision data sample corresponding to(1.0087±0.0044)×10^(10)events collected using the BESIII detector at the BEPCII collider,we firstly search for the lepton number violation decayφ→π^(+)π^(+)e^(-)e^(-)via J/ψ→φη.No obviously signals are found.The upper limit on the branching fraction ofφ→π^(+)π^(+)e^(-)e^(-)is set to be 1.3×10^(-5)at the 90%confidence level.
基金Supported in part by National Key R&D Program of China(2023YFA1606000,2023YFA1606704)National Natural Science Foundation of China(NSFC)(12035009,11875170,11635010,11935015,11935016,11935018,12025502,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Program,CAS(YSBR-101)100 Talents Program of CASThe Institute of Nuclear and Particle Physics(INPAC)Shanghai Key Laboratory for Particle Physics and CosmologyAgencia Nacional de Investigación y Desarrollo de Chile(ANID)Chile(ANID PIA/APOYO AFB230003)ERC(758462)German Research Foundation DFG(FOR5327)Istituto Nazionale di Fisica Nucleare,ItalyKnut and Alice Wallenberg Foundation(2021.0174,2021.0299)Ministry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF-2022R1A2C1092335)National Science and Technology fund of MongoliaPolish National Science Centre(2024/53/B/ST2/00975)STFC(United Kingdom)Swedish Research Council(2019.04595)U.S.Department of Energy(DE-FG02-05ER41374)。
文摘Lepton number violation decayω→π^(+)π^(+)e^(-)e^(-)+c.c.is searched for via J/ψ→ωηusing a data sample of(1.0087±0.0044)×10^(10)J/ψevents collected via the BESIII detector at the BEPCII collider.No significant signal is observed,and the upper limit on the branching fraction ofω→π^(+)π^(+)e^(-)e^(-)+c.c.at the 90%confidence level is determined for the first time to be 2.8×10^(-6).
基金Supported in part by the National Key R&D Program of China(2023YFA1606000,2020YFA0406400,2020YFA0406300)the National Natural Science Foundation of China(NSFC)(11635010,11735014,11935015,11935016,11875054,11935018,12025502,12035009,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+12 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)the Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U2032104,U1832207)the 100 Talents Program of CAS,the Excellent Youth Foundation of Henan Scientific Commitee(242300421044)the Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and Cosmology,the German Research Foundation DFG(FOR5327)the Istituto Nazionale di Fisica Nucleare,Italy,the Knut and Alice Wallenberg Foundation(2021.0174,2021.0299)the Ministry of Development of Turkey(DPT2006K-120470),the National Research Foundation of Korea(NRF-2022R1A2C1092335)the National Science and Technology Fund of Mongoliathe National Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research,and Innovation of Thailand(B16F640076,B50G670107)the Polish National Science Center(2019/35/O/ST2/02907)the Swedish Research Council(2019.04595)the Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)the US Department of Energy(DE-FG02-05ER41374)。
文摘We search for the leptonic decay D^(+)→e^(+)ν_(e)using an e+e-collision data sample with an integrated luminosity of 20.3 fb-1collected with the BESIII detector at a center-of-mass energy of 3.773 GeV.Significant signal is not observed,and an upper limit on the branching fraction of D^(+)→e^(+)ν_(e)is set as 9.7×10^(-7),at a confidence level of 90%.Our upper limit is an order of magnitude smaller than the previous limit for this decay mode.
基金supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400,2023YFA1606000)National Natural Science Foundation of China(NSFC)(12205141,11635010,11735014,11935015,11935016,11935018,12025502,12035009,12035013,12061131003,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017,12361141819)+16 种基金Natural Science Foundation of Hunan Province(2024JJ2044)the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)100 Talents Program of CASThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyGerman Research Foundation DFG(FOR5327)Istituto Nazionale di Fisica Nucleare,ItalyKnut and Alice Wallenberg Foundation(2021.0174,2021.0299)Ministry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF2022R1A2C1092335)National Science and Technology fund of MongoliaNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation of Thailand(B16F640076,B50G670107)Polish National Science Centre(2019/35/O/ST2/02907)Swedish Research Council(2019.04595)The Swedish Foundation for International Cooperation in Research and Higher Education(CH2018-7756)U.S.Department of Energy(DE-FG02-05ER41374)。
文摘Utilizing 4.5 fb^(-1)ofe^(+)e^(-)annihilation data collected at center-of-mass energies ranging from 4599.53 MeV to 4698.82 MeV by the BESIII detector at the BEPCII collider,we searched for singly Cabibbo-suppressed hadronic decaysΛ_(c)^(+)→Σ^(0)K^(+)π^(0)andΛ_(c)^(+)→Σ^(0)K^(+)π^(+)π^(−)and with a single-tag method.No significant signals were observed for both decays.The upper limits on the branching fractions at the 90%confidence level were determined to be 5.0×10^(-4)for and forΛ_(c)^(+)→Σ^(0)K^(+)π^(0)and 6.5×10^(-4)forΛ_(c)^(+)→Σ^(0)K^(+)π^(+)π^(−).
基金Supported in part by National Key R&D Program of China under Contracts Nos.Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(11975118,11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12061131003,12075252,12192260,12192261,12192262,12192263,12192264,12192265)+19 种基金the Natural Science Foundation of Hunan Province of China(2019JJ30019)the Science and Technology Innovation Program of Hunan Province(2020RC3054)the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union Horizon 2020 research and innovation programme under Contract No.Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(43159800)Collaborative Research Center CRC 1044,FOR 2359,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0012069)。
文摘Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESⅢdetector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8 fb^(-1),the process e^(+)e^(-)→pppñπ+c.c.is observed for the first time with a statistical significance of 11.5σ.The average Born cross sections in the energy ranges of(4.160,4.380)GeV,(4.400,4.600)GeV and(4.610,4.700)GeV are measured to be(21.5±5.7±1.2)fb,(46.3±10.6±2.5)fb and(59.0±9.4±3.2)fb,respectively,where the first uncertainties are statistical and the second are systematic.The line shapes of the pñ and ppπ^(-)invariant mass spectra are consistent with phase space distributions,indicating that no hexaquark or di-baryon state is observed.
基金Supported in part by National Key R&D Program of China(Grant Nos.2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC)(Grant Nos.11635010,11735014,11805086,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265)+18 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(Grant No.U1832207)the CAS Center for Excellence in Particle Physics(CCEPP)100 Talents Program of CASFundamental Research Funds for the Central Universities,Lanzhou University,University of Chinese Academy of SciencesThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyERC(Grant No.758462)European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement(Grant No.894790)German Research Foundation DFG(Grant No.443159800),Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(Grant No.DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(Grant No.B16F640076)Olle Engkvist Foundation(Grant No.200-0605)STFC(United Kingdom)Suranaree University of Technology(SUT),Thailand Science Research and Innovation(TSRI),and National Science Research and Innovation Fund(NSRF)(Grant No.160355)The Royal Society,UK(Grant Nos.DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(Grant No.DE-FG02-05ER41374)。
文摘We report a search for a heavier partner of the recently observed Z_(cs)(3985)^(-) state,denoted as Z_(cs)^('-),in the process e^(+)e^(−)→K^(+)D_(s)^(∗−) D^(∗0 )+ c.c.,based on e^(*)e^(-)collision data collected at the center-of-mass energies of √s=4.661,4.682 and 4.699 GeV with the BESIII detector.The Z_(cs)^('-) is of interest as it is expected to be a candidate for a hidden-charm and open-strange tetraquark.A partial-reconstruction technique is used to isolate K^(+)recoil-mass spectra,which are probed for a potential contribution from Z_(cs)^('-)→D_(s)^(∗−) D^(∗0 )+ c.c.We find an excess of Z_(cs)^('-)→D_(s)^(*-)-D^(*0)(c.c.)candidates with a significance of 2.1o,after considering systematic uncertainties,at a mass of(4123.5±0.7_(sat)±4.7_(syst.))MeV/c^(2).As the data set is limited in size,the upper limits are evaluated at the 90%confidence level on the product of the Born cross sections(σ^(Borm))and the branching fraction(B)of Z_(cs)^('-)→D_(s)^(*-)-D^(*0),under different assumptions of the Z_(cs)^('-) mass from 4.120 to 4.140 MeV and of the width from 10 to 50 MeV at the three center-of-mass energies.The upper limits of σ^(Born).B are found to be at the level of O(1)pb at each energy.Larger data samples are needed to confirm the Z_(cs)^('-) state and clarify its nature in the coming years.
基金Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)(11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12061131003)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union Horizon 2020 research and innovation programme(Marie Sklodowska-Curie grant agreement No 894790)German Research Foundation DFG(443159800),Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundOlle Engkvist Foundation(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)(2016.0157)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374,DE-SC-0012069)。
文摘The integrated luminosities of data samples collected in the BESⅢ experiment in 2016-2017 at centerof-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events.The integrated luminosities of old datasets collected in 2010-2014 are updated by considering corrections related to detector performance,offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter,which can haphazardly occur.
基金Supported in part by National Key R&D Program of China(2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC)(11635010,11735014,11805086,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265)+17 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASFundamental Research Funds for the Central Universities,Lanzhou University,University of Chinese Academy of SciencesThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(443159800),Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(B16F640076)STFC(United Kingdom)Suranaree University of Technology(SUT),Thailand Science Research and Innovation(TSRI),and National Science Research and Innovation Fund(NSRF)(160355)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374)。
文摘From December 2019 to June 2021,the BESⅢ experiment collected approximately 5.85 fb^(−1) of data at center-of-mass energies between 4.61 and 4.95 GeV.This is the highest collision energy BEPCⅡ has reached to date.The accumulated e^(+)e^(−) annihilation data samples are useful for studying charmonium(-like)states and charmed-hadron decays.By adopting a novel method of analyzing the production of A_(c)^(+)A_(c)^(-) pairs in e^(+)e^(−) annihilation,the center-of-mass energies are measured with a precision of 0.6 MeV.Integrated luminosities are measured with a precision of better than 1% by analyzing the events of large-angle Bhabha scattering.These measurements provide important inputs to analyses based on these data samples.
基金supported in part by National Key Research and Development Program of China(2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC,11975118,11635010,11735014,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265,12061131003)+18 种基金the Natural Science Foundation of Hunan Province of China(2019JJ30019)the Science and Technology Innovation Program of Hunan Province(2020RC3054)the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH040)100 Talents Program of CASThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and Cosmology,ERC(758462)European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(443159800)Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources and Institutional Development,Research and Innovation(B16F640076)STFC(United Kingdom)Suranaree University of Technology(SUT),Thailand Science Research and Innovation(TSRI),and National Science Research and Innovation Fund(NSRF,160355)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374)。
文摘Using(448.1±2.9)×10^(6)ψ(3686)for the weak baryonic decayψ(3686)→Λc+∑-+c.c..The analysis procedure is optimized using a blinded method.No significant signal is observed,and the upper limit on the branching fraction(B)ofψ(3686)→Λc+∑-+c.c.is set as 1.4×10^(-5)at the 90%confidence level.
基金Supported in part by National Key R&D Program of China(2020YFA0406400,2020YFA0406300)National Natural Science Foundation of China(NSFC)(11635010,11735014,11805086,11835012,11935015,11935016,11935018,11975011,11961141012,12022510,12025502,12035009,12035013,12192260,12192261,12192262,12192263,12192264,12192265)+20 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1832207)the CAS Center for Excellence in Particle Physics(CCEPP)100 Talents Program of CASFundamental Research Funds for the Central Universities,Lanzhou University,University of Chinese Academy of SciencesThe Institute of Nuclear and Particle Physics(INPAC)Shanghai Key Laboratory for Particle Physics and CosmologyERC(758462)German Research Foundation DFG(443159800)Collaborative Research Center CRC 1044,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Science and Technology fundNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(B16F640076STFC)(United Kingdom)Suranaree University of Technology(SUT)Thailand Science Research and Innovation(TSRI)National Science Research and Innovation Fund(NSRF)(160355)The Royal Society,UK(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy(DEFG02-05ER41374)。
文摘Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb-1,collected by the BESⅢdetector in the energy region between 4599.53 MeV and 4698.82 MeV,we report the first observations of the Cabibbo-suppressed decaysΛ_(c)^(+)→nπ^(+)π^(0),Λ_(c)^(+)→nπ^(+)π^(-)π^(+),and the Cabibbo-favored decayΛ_(c)^(+)→nK^(-)π^(+)π^(+)with statistical significances of 7.9σ,7.8σ,and>10σ,respectively.The branching fractions of these decays are measured to be B(Λ_(c)^(+)→nπ^(+)π^(0))=(0.64±0.09±0.02)%,B(Λ_(c)^(+)→nπ^(+)π^(-)π^(+))=(0.45±0.07±0.03)%,and B(Λ_(c)^(+)→nK^(-)π^(+)π^(+))=(1.90±0.08±0.09)%,where the first uncertainties are statistical and the second are systematic.We find that the branching fraction of the decayΛ_(c)^(+)→nπ^(+)π^(0)is about one order of magnitude higher than that ofΛ_(c)^(+)→nπ^(+).
基金Supported in part by National Key R&D Program of China(2020YFA0406300,2020YFA0406400)National Natural Science Foundation of China(NSFC)under Contracts Nos.(11625523,11635010,11735014,11822506,11835012,11935015,11935016,11935018,11961141012,12022510,12025502,12035009,12035013,12061131003)+16 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility ProgramJoint Large-Scale Scientific Facility Funds of the NSFC and CAS under Contracts Nos.(U1732263,U1832207)CAS Key Research Program of Frontier Sciences under Contract No.(QYZDJ-SSW-SLH040)100 Talents Program of CASINPAC and Shanghai Key Laboratory for Particle Physics and CosmologyERC under Contract No.(758462)European Union Horizon 2020 research and innovation programme under Contract No.Marie Sklodowska-Curie grant agreement No(894790)German Research Foundation DFG under Contracts Nos.(443159800),Collaborative Research Center CRC 1044,FOR 2359,GRK 214Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey under Contract No.(DPT2006K-120470)National Science and Technology fundOlle Engkvist Foundation under Contract No.(200-0605)STFC(United Kingdom)The Knut and Alice Wallenberg Foundation(Sweden)under Contract No.(2016.0157)The Royal Society,UK under Contracts Nos.(DH140054,DH160214)The Swedish Research CouncilU.S.Department of Energy under Contracts Nos.(DE-FG02-05ER41374,DE-SC-001206)。
文摘The cross sections of e^(+)e^(-)→K^(+)K^(-)J/Ψat center-of-mass energies from 4.127 to 4.600 GeV are measured based on 15.6 fb-1data collected with the BESⅢ detector operating at the BEPCⅡ storage ring.Two resonant structures are observed in the line shape of the cross sections.The mass and width of the first structure are measured to be(4225.3±2.3±21.5)MeV and(72.9±6.1±30.8)MeV,respectively.They are consistent with those of the established Y(4230).The second structure is observed for the first time with a statistical significance greater than 8σ,denoted as Y(4500).Its mass and width are determined to be(4484.7±13.3±24.1)MeV and(111.1±30.1±15.2)MeV,respectively.The first presented uncertainties are statistical and the second ones are systematic.The product of the electronic partial width with the decay branching fractionΓ(Y(4230)→e^(+)e^(−))B(Y(4230)→K^(+)K^(−)J/Ψ)is reported.
基金supported by the 973 Program (No. 2011CB808104)the National Natural Science Foundation of China (Nos. 11335013, 10834008, 11125526, 60921004, and 11305236)+1 种基金the International S&T Cooperation Program of China (No. 2011DFA11300)Shanghai Natural Science Foundation (No. 13ZR1463300)
文摘The effects of ion motion on the generation of short-cycle relativistic laser pulses during radiation pressure acceleration are investigated by analytical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by ion motion is sharper compared with the case of the electron shutter only. In this study, the ions further modulate the short-cycle pulses transmitted. A 3.9 fs laser pulse with an intensity of 1.33×1021W cm-2is generated by properly controlling the motions of the electron and ion in the simulations. The short-cycle laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.
基金supported by the National Key R&D Program of China(No.2019YFA0905300)Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(No.TSBICIPKJGG-001-14)+1 种基金the National Natural Science Foundation of China(No.22078126)Qing Lan Project in Jiangsu Province and Fundamental Research Funds for the Central Universities(JUSRP221025).
文摘With the increasing application of steroid drugs as therapeutics,the demand for steroid drugs is increasing.In recent years,biological synthesis has become the standard approach to produce steroid intermediates,while this method still faces some problems such as unclear metabolic pathway and low yield.Mycobacterium sp.LY-1 can convert phytosterols into 9α-hydroxyandrost-4-ene-3,17-dione(9α-OH-AD)which is a key intermediate for the synthesis of steroid drugs with long effective time and significant pharmacological activity.In this work,the whole-genome sequence of the Mycobacterium sp.LY-1 was analyzed,and the side-chain degradation pathway of phytosterols in Mycobacterium sp.LY-1 was proposed.Meanwhile,the related key enzymes of phytosterol metabolism were identified through qRT-PCR.Through overexpressing the key enzymes including KshA2,KshB,and HsdB,the yield of 9α-OH-AD increased by 12.7%compared to that of the control.Furthermore,by optimizing the medium and culture conditions,the yield of 9α-OH-AD reached 50.4%.The maxi-mum yield was 30.7%higher than that of the original strain.The results are of significance for the industrial production of 9α-OH-AD using metabolic engineering methods.
基金Supported in part by the National Key R&D Program of China(2020YFA0406300,2020YFA0406400)the National Natural Science Foundation of China(NSFC)(11625523,11635010,11735014,11835012,11935015,11935016,11935018,11961141012,12025502,12035009,12035013,12061131003,12105276,12122509,12192260,12192261,12192262,12192263,12192264,12192265,12221005,12225509,12235017)+15 种基金the Chinese Academy of Sciences(CAS)Large-Scale Scientific Facility Programthe CAS Center for Excellence in Particle Physics(CCEPP)Joint Large-Scale Scientific Facility Funds of the NSFC and CAS(U1732263,U1832103,U1832207,U2032111)CAS Key Research Program of Frontier Sciences(QYZDJ-SSW-SLH003,QYZDJ-SSW-SLH040)100 Talents Program of CASThe Institute of Nuclear and Particle Physics(INPAC)and Shanghai Key Laboratory for Particle Physics and CosmologyEuropean Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement(894790)German Research Foundation DFG(455635585),Collaborative Research Center CRC 1044,FOR5327,GRK 2149Istituto Nazionale di Fisica Nucleare,ItalyMinistry of Development of Turkey(DPT2006K-120470)National Research Foundation of Korea(NRF-2022R1A2C1092335)National Science and Technology fund of MongoliaNational Science Research and Innovation Fund(NSRF)via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation of Thailand(B16F640076)Polish National Science Centre(2019/35/O/ST2/02907)The Swedish Research CouncilU.S.Department of Energy(DE-FG02-05ER41374)。
文摘Using e^(+)e^(−)annihilation data corresponding to an integrated luminosity of 2.93 fb^(−1)taken at the center-of-mass energy√s=3.773 GeV with the BESIII detector,a joint amplitude analysis is performed on the decays D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η).The fit fractions of individual components are obtained,and large interferences among the dominant components of the decays D^(0)→a_(1)(1260)π,D^(0)→π(1300)π,D^(0)→ρ(770)ρ(770),and D^(0)→2(ππ)_(S)are observed in both channels.With the obtained amplitude model,the CP-even fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are determined to be(75.2±1.1_(stat).±1.5_(syst.))%and(68.9±1.5_(stat).±2.4_(syst.))%,respectively.The branching fractions of D^(0)→π^(+)π^(−)π^(+)π^(−)and D^(0)→π^(+)π^(−)π^(0)π^(0)(non-η)are measured to be(0.688±0.010_(stat.)±0.010_(syst.))%and(0.951±0.025_(stat.)±0.021_(syst.))%,respectively.The amplitude analysis provides an important model for the binning strategy in measuring the strong phase parameters of D^(0)→4πwhen used to determine the CKM angleγ(ϕ_(3))via the B^(−)→DK^(−)decay.
