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基于蒙特卡罗模拟的透射式XRD背景的定量分析
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作者 袁靖茜 黄宁 +2 位作者 何泽 彭博 王鹏 《原子能科学技术》 EI CAS CSCD 北大核心 2024年第2期441-450,共10页
XRD背景主要来源于空气、装置和样品中光子的散射,XRD分析需准确扣除背景,常用的扣背景方法具有一定的局限。蒙特卡罗模拟可实现光子的甄别与统计,因此可将其用于XRD背景来源的定量分析。相干散射的模拟中需考虑物质的Form Factor,这可... XRD背景主要来源于空气、装置和样品中光子的散射,XRD分析需准确扣除背景,常用的扣背景方法具有一定的局限。蒙特卡罗模拟可实现光子的甄别与统计,因此可将其用于XRD背景来源的定量分析。相干散射的模拟中需考虑物质的Form Factor,这可由Baró等的拟合式、独立原子模型或德拜公式给出;在20 keV能量及透射几何模式下,通过对骨、尼龙、水等物质的XRD模拟,对探测器中光子来源进行了区分和统计。结果表明,德拜公式计算的空气背景大于独立原子模型;空气散射在小角度时背景占比大,随散射角的增加从100%减小至40%以下,而样品中康普顿散射的计数占比则从0增大至60%以上。该方法可对不同样品组成以及复杂装置结构的XRD背景进行定量分析。 展开更多
关键词 蒙特卡罗模拟 XRD背景 Form Factor GEANT4
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Neutral Pion Electromagnetic Form Factor as a Bound System of 3 + 1 Dimensional QCD
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作者 Teruo Kurai 《Journal of Modern Physics》 2024年第7期1036-1044,共9页
We investigate a neutral pion electromagnetic form factor in momentum space and obtain Gaussian-like function for it. The characteristic form of our neutral pion electromagnetic form factor is consistent with the resu... We investigate a neutral pion electromagnetic form factor in momentum space and obtain Gaussian-like function for it. The characteristic form of our neutral pion electromagnetic form factor is consistent with the results published by Jefferson Lab Hall A Collaboration. . 展开更多
关键词 Neutral Pion Electromagnetic Form Factor Gaussian-Like Function
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Planar morphology and controlling factors of the gullies in the Yuanmou Dry-hot Valley based on field investigation 被引量:3
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作者 DENG Qingchun MIAO Fang +5 位作者 ZHANG Bin LUO Mingliang LIU Hui LIU Xiaojiao QIN Fachao LIU Gangcai 《Journal of Arid Land》 SCIE CSCD 2015年第6期778-793,共16页
The plane form of a gully can provide a basis for evaluating the gully volume and erosion rate, acting process, and evolutionary stage. For describing the planar characteristics of a permanent gully and understanding ... The plane form of a gully can provide a basis for evaluating the gully volume and erosion rate, acting process, and evolutionary stage. For describing the planar characteristics of a permanent gully and understanding their controlling factors, this study, utilizing a total station and GPS RTK, measured the shoulder lines and channel curves of 112 gullies in six sites of the Yuanmou Dry-hot Valley and then mapped them by Arc GIS software and calculated nine parameters. The results showed that the channel lengths range from 10.88 to 249.11 m; the widths range from 6.20 to 40.99 m; the perimeters range from 54.11 to 541.67 m; the gully areas range from 153.02 to 6,930.30 m2; the left-side areas range from 92.93 to 4,027.20 m2; and the right-side areas range from 63.65 to 3,539.77 m2. The slightly sinuous and straight gullies account for 73.21% of the total gullies; the quantity of the right skewed gullies is 8.93% greater than that of the left skewed ones based on the symmetry ratio; the shape ratios range from 1.12 to 1.40 and the morphology ratios from 0.038 to 1.294; the fractal dimension is 1.192. Gullies in different sites have diverse planar characteristics. Except for the symmetry index, which was close to a negatively skewed distribution, all of the other parameters had the characteristic of positively skewed distribution. The gully area is related to the length and width, but the gully length has a weak correlation with the width. The evolutionary stage, topographic conditions, strata, soil properties, and piping erosion played very important roles in the gully planar morphology. This study could provide useful information for controlling gully erosion and safeguarding human habitation and engineering buildings. 展开更多
关键词 gully plane form morphological parameters controlling factors Yuanmou Dry-hot Valley
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Quantifying.Associations among Dimensions of Ears and Their Form Factors in Maize(Zea Mays)Using Dimensional Analysis
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作者 Hongbo CAO Gaimei LIANG Jinzhong YANG 《Agricultural Science & Technology》 CAS 2016年第10期2287-2292,共6页
Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars ... Ear morphological traits such as volume and shape are important features of maize and the quantitative associations among them can help understand kernel yield determination. 150 mature ears each of 4 maize cultivars were collected from field experiments, and ear length(L), diameter(D), area(S) and volume(V) were recorded for individual ears, kernel weight per ear also recorded for a portion of the examined ears. Following principles of dimensional analysis, 8 theoretical equations of 3 sets,which relate ear higher dimensions to its length and diameter, were developed and parameterized and validated with the field observations. The 3 optimized equations showed that the shape of ears in maize can be featured with 3 dimensionless form factors, namely diameter-to-length ratio(c=D/L), areal form factor(b=S/L/D), and volumetric form factor(a=V/L/D/D). Statistically,all of them were significantly different among cultivars, and a's values varied from 0.582 to 0.612, and b's 0.839-0.868, and c's 0.242-0.308. Volumetric form factor and areal form factor could estimate precisely ear volume and area respectively, but diameter-to-length ratio was not suitable to estimate ear diameter by its length. Ear volume explained almost all variation of ear kernel weight and product L*D*D did the same substantially. Dimensional analysis proved to be promising in understanding relationship among morphological traits of ears in maize. Its application in crop researches should improve our knowledge of the physical properties of crop plants. 展开更多
关键词 Maize(Zea Mays) Dimensional analysis Ear shape Volumetric form factors Ear volume Diameter-to-length ratio Ear kernel weight
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Gravitational form factors of the proton from near-threshold vector meson photoproduction
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作者 王晓云 曾凡聪 张纪元 《Chinese Physics C》 SCIE CAS CSCD 2024年第5期226-234,共9页
We systematically analyze the quark and gluon gravitational form factors(GFFs)of the proton by connecting the energy-momentum tensor and near-threshold vector meson photoproduction(NTVMP).Specifically,the quark contri... We systematically analyze the quark and gluon gravitational form factors(GFFs)of the proton by connecting the energy-momentum tensor and near-threshold vector meson photoproduction(NTVMP).Specifically,the quark contributions of GFFs are determined by applying global fitting to the cross section of the lightest vector mesonρ0 photoproduction.Combined with the gluon GFFs obtained from heavy quarkonium J/ψphotoproduction data,the complete GFFs are obtained and compared with the experimental results and lattice quantum chromodynamics determinations.In addition,we use the resonance via Padé(RVP)method based on the Schlessinger point method to obtain a model-independent quark D-term distribution through direct analytical continuation of deeply virtual Compton scattering experimental data.If errors are considered,the results obtained with RVP are essentially consistent with those obtained by NTVMP.Moreover,the comprehensive information on GFFs helps to uncover the mass distribution and mechanical properties inside the proton.This study is not only an important basis for delving into the enigmatic properties of the proton,but also has significance for theoretically guiding future JLab and EIC experimental measurements. 展开更多
关键词 gravitational form factors properties of the proton vector mesonphotoproduction Schlessinger point method
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CFD-Based Method of Determining Form Factor k for Different Ship Types and Different Drafts 被引量:5
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作者 Jinbao Wang Hai Yu +1 位作者 Yuefeng Zhang Xiaoqing Xiong 《Journal of Marine Science and Application》 CSCD 2016年第3期236-241,共6页
The value of form factor k at different drafts is important in predicting full-scale total resistance and speed for different types of ships. In the ITTC community, most organizations predict form factor k using a low... The value of form factor k at different drafts is important in predicting full-scale total resistance and speed for different types of ships. In the ITTC community, most organizations predict form factor k using a low-speed model test. However, this method is problematic for ships with bulbous bows and transom. In this article, a Computational Fluid Dynamics(CFD)-based method is introduced to obtain k for different type of ships at different drafts, and a comparison is made between the CFD method and the model test. The results show that the CFD method produces reasonable k values. A grid generating method and turbulence model are briefly discussed in the context of obtaining a consistent k using CFD. 展开更多
关键词 form factor computational fluid dynamics(CFD) Prohaska method model test different ship type different draft
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Numerical Study on Scale Effect of Form Factor for DTMB5415, KCS,KVLCC2, and 4000TEU Container Ship 被引量:3
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作者 WANG Zhan-zhi MIN Shao-song PENG Fei 《China Ocean Engineering》 SCIE EI CSCD 2021年第5期767-778,共12页
Four ships,a twin-propeller naval ship,two single-propeller container ships,and a single-propeller very large crude carrier(VLCC),were studied to investigate the scale effect of the form factor.The viscous flow fields... Four ships,a twin-propeller naval ship,two single-propeller container ships,and a single-propeller very large crude carrier(VLCC),were studied to investigate the scale effect of the form factor.The viscous flow fields of the ships at different scales were solved numerically via the Reynolds-averaged Navier–Stokes method combined with the shear stress transport k–ωturbulence model.The numerical method was validated through comparisons with experimental data,and numerical uncertainty analysis was carried out based on the ITTC recommended procedure.On this basis,scale effects of the form factor were analyzed using different friction lines,and scale effects of flow fields and the mean axial wake fractions were further analyzed in details.The results showed that the form factor exhibited scale effects when adopting the ITTC-1957 line,and it increased with the increase in the Reynolds number.The scale effect of the form factor reduces the prediction precision of the full-scale ship resistance.The friction line has a significant effect on the form factor.The form factor exhibits little dependence on the Reynolds number when using the numerical friction line or the Katsui line,which is useful for full-scale ship resistance predictions.With the increasing Reynolds number,the boundary layer thickness becomes thinner and the axial velocity contour contracts toward the center plane,and there is nearly a linear relationship between the reciprocal of mean axial wake fraction on propeller disc and Reynolds number in logarithmic scale for the three types of ship forms. 展开更多
关键词 form factor scale effect ITTC-1957 line numerical calculation flow field
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Numerical Prediction of Form Factor and Wave Interference of A Trimaran for Different Outrigger Positions 被引量:1
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作者 Ali DOGRUL Burak YILDIZ 《China Ocean Engineering》 SCIE EI CSCD 2022年第2期279-288,共10页
Trimaran hydrodynamics have been an important research topic in recent years.Trimarans have even been chosen for naval surface combatants.In this case,investigation of a trimaran with different outrigger positions is ... Trimaran hydrodynamics have been an important research topic in recent years.Trimarans have even been chosen for naval surface combatants.In this case,investigation of a trimaran with different outrigger positions is important and necessary for better hydrodynamic performance.This paper focuses on the numerical investigation of trimaran hydrodynamics.The trimaran model used in this study is a 1/80 scale high-speed displacement frigate-type concept developed by the Center for Innovation in Ship Design(CISD)at Naval Surface Warfare Center,Carderock Division(NSWCCD).The numerical simulations were conducted for different outrigger positions at low and moderate Froude numbers by using commercial CFD software solving URANS equations.A verification and validation study was carried out for the numerical method in one configuration and one ship velocity.The existing experimental results for the trimaran resistance in the literature were used for validation.Five different outrigger positions were analyzed and the form factor of each configuration was calculated by the Prohaska method.The total resistance was decomposed to its components using the form factor.The interference factor was calculated for each configuration in terms of total resistance,residual resistance and wave resistance.Also,wave profiles using the longitudinal wave cuts in different locations were obtained both numerically and experimentally.It was concluded that the outrigger position had different effects on the interference,total resistance and wave profile at different Froude numbers.It was also shown that the CFD results were in good agreement with the experimental data in all configurations.In conclusion,this study presents the results of interference effects for different trimaran configurations in terms of wave resistance in addition to the total resistance and residual resistance.The numerical method was validated not only with the total resistance test data but also the longitudinal wave profiles along the hull. 展开更多
关键词 CFD form factor wave interference wave profile OUTRIGGER TRIMARAN
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Theoretical Study of the Nuclear Charge Distributions of Tin Isotopes
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作者 刘健 褚衍运 任中洲 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第7期614-618,共5页
Nuclear binding energies, charge radii and the charge distributions of even-even tin (Sn) isotopes are calculated using relativistic mean field theory, and the theoretical results are found to be in accordance with ... Nuclear binding energies, charge radii and the charge distributions of even-even tin (Sn) isotopes are calculated using relativistic mean field theory, and the theoretical results are found to be in accordance with the experimental data. The nuclear charge form factors for Sn isotopes are calculated using the phase-shift analysis method. It is shown that the minima of the charge form factors shift upward and inward with an increase in the neutron number of the Sn isotopes. 展开更多
关键词 elastic electron-nucleus scattering relativistic mean-field theory phase-shift analysis method nuclear charge form factor
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Thomson scattering off a pair (electron-positron) plasma
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作者 郑坚 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第5期1028-1034,共7页
Thomson scattering off a pair (electron-positron) plasma is theoretically investigated in the collisionless and collisional limits respectively. Our calculations show that the power spectrum of the Thomson scatterin... Thomson scattering off a pair (electron-positron) plasma is theoretically investigated in the collisionless and collisional limits respectively. Our calculations show that the power spectrum of the Thomson scattering off a collisionless pair plasma is just proportional to the velocity distribution function of the particles in the plasma. Collective modes in the plasma do not have any effects on the Thomson scattering spectrum because of the correlation between the negatively- and positively-charged particles. In the collisional limit, the power spectrum of the Thomson scattering presents three spikes: two peaks correspond to two contra-propagating sound waves and one peak corresponds to an entropy wave. 展开更多
关键词 pair plasma Thomson scattering dynamic form factor
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Deuteron electromagnetic form factors and tensor polarization observables in the framework of the hard-wall AdS/QCD model
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作者 Narmin Huseynova Shahin Mamedov Jannat Samadov 《Chinese Physics C》 SCIE CAS CSCD 2023年第1期55-62,共8页
We study the electromagnetic form factors and tensor polarization observables of the deuteron in the framework of the hard-wall AdS/QCD model.We find a profile function for the bulk twistτ=6 vector field,which descri... We study the electromagnetic form factors and tensor polarization observables of the deuteron in the framework of the hard-wall AdS/QCD model.We find a profile function for the bulk twistτ=6 vector field,which describes the deuteron on the boundary and fix the infrared boundary cut-off of AdS space in accordance with the ground state mass of the deuteron.We obtain the deuteron charge monopole,quadrupole,and magnetic dipole form factors and tensor polarization observables from the bulk Lagrangians for the deuteron and photon field interactions.We plot the momentum transfer dependence of the form factors and tensor polarization observables and compare our numerical results with those in the soft-wall model and experimental data. 展开更多
关键词 DEUTERON electromagnetic form factors structure functions tensor polarization observables hard-wall model
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Contributions to the nucleon form factors from bubble and tadpole diagrams
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作者 高正阳 王平 杨明炀 《Chinese Physics C》 SCIE CAS CSCD 2023年第2期63-70,共8页
The nonlocal chiral effective theory is applied to investigate the electromagnetic and strange form factors of nucleons.The bubble and tadpole diagrams are included in the calculation.With the contributions from bubbl... The nonlocal chiral effective theory is applied to investigate the electromagnetic and strange form factors of nucleons.The bubble and tadpole diagrams are included in the calculation.With the contributions from bubble and tadpole diagrams,the obtained electromagnetic form factors are close to the results without these contributions as long as the low energy constants c_(1) and c_(2) are properly chosen,while the magnitudes of strange form factors become larger.The electromagnetic form factors are in good agreement with the experimental results,while the magnitudes of strange form factors are larger than the lattice data. 展开更多
关键词 effective field theory nonlocal Lagrangian electromagnetic form factors strange form factors
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B_((s))→D^(∗∗)_((s))form factors in HQEFT and model independent analysis of relevant semileptonic decays with NP effects
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作者 左亚兵 金洪瑶 +3 位作者 田婧赢 伊佳 宫涵宇 潘婷婷 《Chinese Physics C》 SCIE CAS CSCD 2023年第10期55-76,共22页
The form factors of B(s)decays into P-wave excited charmed mesons(including D∗0(2300),D1(2430),D1(2420),D∗2(2460)and their strange counterparts,denoted generically as D∗∗(s))are systematically calculated via QCD sum r... The form factors of B(s)decays into P-wave excited charmed mesons(including D∗0(2300),D1(2430),D1(2420),D∗2(2460)and their strange counterparts,denoted generically as D∗∗(s))are systematically calculated via QCD sum rules in the framework of heavy quark effective field theory(HQEFT).We consider contributions up to the next leading order of heavy quark expansion and give all the relevant form factors,including the scalar and tensor ones only relevant for possible new physics effects.The expressions for the form factors in terms of several universal wave functions are derived via heavy quark expansion.These universal functions can be evaluated through QCD sum rules.Then,the numerical results of the form factors are presented.With the form factors given here,a model independent analysis of relevant semileptonic decays B(s)→D∗∗(s)lν¯l is performed,including the contributions from possible new physics effects.Our predictions for the differential decay widths,branching fractions,and ratios of branching fractions R(D∗∗(s))may be tested in more precise experiments in the future. 展开更多
关键词 excited charmed meson form factor HQEFT semileptonic decay NP effects
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Gluon gravitational form factors of protons from charmonium photoproduction
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作者 王晓云 曾凡聪 王全进 《Chinese Physics C》 SCIE CAS CSCD 2023年第7期81-88,共8页
Inspired by the recent near-threshold J/ψphotoproduction measurements,we discuss gluon gravitational form factors(GFFs)and internal properties of the proton.This work presents a complete analysis of the proton gluon ... Inspired by the recent near-threshold J/ψphotoproduction measurements,we discuss gluon gravitational form factors(GFFs)and internal properties of the proton.This work presents a complete analysis of the proton gluon GFFs connecting the gluon part of the energy-momentum tensor and the heavy quarkonium photoproduction.In particular,a global fitting of the J/ψdifferential and total cross section experimental data is used to determine the gluon GFFs as functions of the squared momentum transfer t.Combined with the quark contributions to the D-term form factor extracted from the deeply virtual Compton scattering experiment,the total D-term is obtained to investigate their applications in describing the proton mechanical properties.These studies provide a unique perspective on investigating the proton gluon GFFs and important information for enhancing QCD constraints on the gluon GFFs. 展开更多
关键词 gravitational form factors properties of the proton charmonium photoproduction
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D^(+)→π^(+)v■decay process within the QCDSR approach
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作者 陈宇 付海冰 +2 位作者 钟涛 吴胜波 黄冬 《Chinese Physics C》 SCIE CAS CSCD 2024年第6期69-81,共13页
In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ... In this paper,we investigate the charmed meson rare decay process D^(+)→π^(+)v■using an approach based on QCD sum rules.First,the pion twist-2,3 distribution amplitude(DA)moments<ξ_(2)^(n);|μand<ξ3;π(p,σ),n>|μ,are calculated up to the tenth and fourth orders,respectively,in the QCD sum rules according to the background field theory.After constructing the light-cone harmonic oscillator model for the pion twist-2,3 D As,we obtain their behaviors by matching the calculatedξ-moments.Then,the D→πtransition form factors(TFFs)are calculated using an approach based on QCD light-cone sum rules.The vector form factor at the large recoil region is f_(+)^(D)→^(π)(0)=0.627_(-0.080)^(+0.120).Using the rapidly converging simplified series expansion of z(q^(2),t),we present the TFFs and corresponding angular coefficients in the whole squared momentum transfer physical region.Based on nonstandard neutrino interactions,the■^(0)→π^(+)e■_(e)decay can be related to the■^(0)→π^(+)e■_(e)decay indirectly.Thus,we first describe the semileptonic decay process■^(0)→π^(+)e■_(e),differential decay widths,and branching fraction with B(■^(0)→π^(+)e■_(e))=0.308_(-0.066)^(+0.155)×10^(2).The■^(0)→π^(+)e■_(e)differential/total predictions for forward-backward asymmetry,q^(2)-differential flat terms,and lepton polarization asymmetry are also reported.The prediction for the D^(+)→π^(+)v■branching fraction isB(D^(+)→π^(+)v■)=1.85_(-0.46)+^(0.93)×10^(-8). 展开更多
关键词 transition form factors pion LCDAs flavour changing neutral current transition heavy meson semileptonic decays QCD sum rule
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Magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states in the diquark-antidiquark picture
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作者 Ulaş Özdem 《Chinese Physics C》 SCIE CAS CSCD 2024年第1期7-16,共10页
The magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the di... The magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states are calculated within the QCD light-cone sum rules.The compact diquark-antidiquark interpolating currents and the distribution amplitudes of the on-shell photon are used to extract the magnetic and quadrupole moments of these states.The magnetic moments are acquired asμZ_(c)=0.50+0.22−0.22μN,μZ_(c)^(1)=1.22+0.34−0.32μN,andμZ_(c)^(2)=2.40+0.53−0.48μN for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.The magnetic moments evaluated for the Z_(c)4020)+,Z_(c)(4050)+,and Z_(c)(4600)+states are sufficiently large to be experimentally measurable.The magnetic moment is an excellent platform for studying the internal structure of hadrons governed by the quark-gluon dynamics of QCD because it is the leading-order response of a bound system to a weak external magnetic field.The quadrupole moment results are DZ_(c)=(0.20+0.05−0.04)×10^(−3)fm^(2),DZ_(c)^(1)=(0.57+0.07−0.08)×10^(−3)fm^(2),and DZ_(c)^(2)=(0.30+0.05−0.04)×10^(−3)fm^(2)for the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states,respectively.We obtain a non-zero,but small,value for the quadrupole moments of the Z_(c)states,which indicates a non-spherical charge distribution.The nature and internal structure of these states can be elucidated by comparing future experimental data on the magnetic and quadrupole moments of the Z_(c)(4020)^(+),Z_(c)(4050)^(+),and Z_(c)(4600)^(+)states with the results of the present study. 展开更多
关键词 hidden-charm tetraquark states electromagnetic form factors magnetic and quadrupole moments QCD light-cone sum rules
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General properties of the spectral form factor in open quantum systems
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作者 Yi-Neng Zhou Tian-Gang Zhou Pengfei Zhang 《Frontiers of physics》 SCIE CSCD 2024年第3期229-237,共9页
The spectral form factor(SFF)can probe the eigenvalue statistic at different energy scales as its time variable varies.In closed quantum chaotic systems,the SFF exhibits a universal dip-ramp-plateau behavior,which ref... The spectral form factor(SFF)can probe the eigenvalue statistic at different energy scales as its time variable varies.In closed quantum chaotic systems,the SFF exhibits a universal dip-ramp-plateau behavior,which reflects the spectrum rigidity of the Hamiltonian.In this work,we explore the general properties of SFF in open quantum systems.We find that in open systems the SFF first decays exponentially,followed by a linear increase at some intermediate time scale,and finally decreases to a saturated plateau value.We derive general relations between(i)the early-time decay exponent and Lindblad operators;(ii)the long-time plateau value and the number of steady states.We also explain the effective field theory perspective of general behaviors.We verify our theoretical predictions by numerically simulating the Sachdev−Ye−Kitaev(SYK)model,random matrix theory(RMT),and the Bose−Hubbard model. 展开更多
关键词 spectral form factor open quantum system quantum chaos
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Deuteron electromagnetic form factors in transverse plane with a phenomenological Lagrangian approach 被引量:1
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作者 梁翠英 董宇兵 梁伟红 《Chinese Physics C》 SCIE CAS CSCD 2014年第7期50-58,共9页
A phenomenological Lagrangian approach is employed to study the electromagnetic properties of deuteron The deuteron is regarded as a loosely bound state of a proton and a neutron. The deuteron electromagnetic form fac... A phenomenological Lagrangian approach is employed to study the electromagnetic properties of deuteron The deuteron is regarded as a loosely bound state of a proton and a neutron. The deuteron electromagnetic form factors are expressed in light-front representation in the transverse plane. The transverse charge density of the deuteron is discussed. 展开更多
关键词 DEUTERON NUCLEON electromagnetic form factors transverse plane impact parameter space
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On-shell methods for form factors in N = 4 SYM and their applications 被引量:1
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作者 Gang Yang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2020年第7期1-28,共28页
Form factors are quantities that involve both asymptotic on-shell states and gauge invariant operators. They provide a natural bridge between on-shell amplitudes and off-shell correlation functions of operators, thus ... Form factors are quantities that involve both asymptotic on-shell states and gauge invariant operators. They provide a natural bridge between on-shell amplitudes and off-shell correlation functions of operators, thus allowing us to use modern on-shell amplitude techniques to probe into the off-shell side of quantum field theory. In particular, form factors have been successfully used in computing the cusp(soft) anomalous dimensions and anomalous dimensions of general local operators. This review is intended to provide a pedagogical introduction to some of these developments. We will first review some amplitudes background using four-point amplitudes as main examples. Then we generalize these techniques to form factors, including(1) tree-level form factors,(2) Sudakov form factor and infrared singularities, and(3) form factors of general operators and their anomalous dimensions. Although most examples we consider are inN= 4 super-Yang-Mill theory, the on-shell methods are universal and are expected to be applicable to general gauge theories. 展开更多
关键词 form factors helicity amplitudes unitarity method SUPERSYMMETRY
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Electromagnetic form factors of neutron and neutral hyperons in the oscillating point of view 被引量:1
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作者 代安鑫 李中义 +1 位作者 常雷 谢聚军 《Chinese Physics C》 SCIE CAS CSCD 2022年第7期41-46,共6页
Based on the recent precise measurements by the BESIII collaboration for electron–positron annihilation into a neutron and antineutron pair,the effective form factors of the neutron were determined in the time-like r... Based on the recent precise measurements by the BESIII collaboration for electron–positron annihilation into a neutron and antineutron pair,the effective form factors of the neutron were determined in the time-like region,and it was found that the effective form factors of the neutron are smaller than those of the proton.The effective form factors of the neutron show a periodic behaviour,similar to those of the proton.Here,a comparative analysis forΛ,∑^(0)and■hyperons is performed.Fits of the available data on the effective form factors ofΛ,∑^(0)and■with zero charge show an interesting phenomenon in the oscillating behavior of their effective form factors.However,this will need to be confirmed by future precise experiments.Both theoretical and experimental investigations of this phenomenon can shed light on the reaction mechanisms of the electron–positron annihilation processes. 展开更多
关键词 electromagnetic form factors baryon-antibaryon pair production electron-positron annihilation
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