In this paper,we study the ρ-meson electromagnetic form factors(EMFFs)within the framework of the light-front quark model.The physical form factors G_(C,M,Q)(Q^(2))of the ρ-meson,as well as the charged square radius...In this paper,we study the ρ-meson electromagnetic form factors(EMFFs)within the framework of the light-front quark model.The physical form factors G_(C,M,Q)(Q^(2))of the ρ-meson,as well as the charged square radius<r^(2)>,the magnetic moment μ,and the quadrupole moment Q,are calculated,which describe the behaviors of EMFFs at zero momentum transfer.Using the type-Ⅱ replacement,we find that the zero-mode does contribute zero to the matrix element S_(00)^(+).It is found that the“M→M_(0)”replacement improves the angular condition remarkably,which permits different prescriptions of ρ-meson EMFFs to give the consistent results.The residual tiny violation of angular condition needs other explanations beyond the zero-mode contributions.Our results indicate that the relativistic effects or interaction internal structure are weaken in the zero-binding limit.This work is also applicable to other spin-1 particles.展开更多
In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functi...In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functions ЖB, ЖB and that include the three-Fock states contributions to do our discussion. Although the scalar meson fo（980） is widely perceived as the 4-quark bound state （scenario 2）, but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model （scenario 1） for scalar meson fo（980） in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain Fo（0） = F＋（0） = 0.20 ± 0.02, FT（O） = 0.24 4± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.展开更多
The nucleon electromagnetic form factors are investigated within a simple diquark-quark model using the light-front formalism. In this model, baryon is described as a bound state of one quark and one clustering diquar...The nucleon electromagnetic form factors are investigated within a simple diquark-quark model using the light-front formalism. In this model, baryon is described as a bound state of one quark and one clustering diquark. The calculational results are compared with the experimental ones. We also regard the quarks in a baryon as pointlike constituent quarks.展开更多
We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ～ 1 and elastic electromagnetic form factors. Then the electromagnetic form...We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ～ 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state.It may be an effective approach to study the form factor of proton in media.展开更多
Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributi...Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributions, is calculated in the light-front formulism of RCQ model. Recently, this ratio was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the polarization technique. The new data presented span the range and are well described by a linear Q<SUP>2</SUP> fit. Also, the ratio reaches a constant value while Q<SUP>2</SUP> becomes larger than 2 (GeV)<SUP>2</SUP>. Our calculation results are presented and appear to be consistent with the experimental ones.展开更多
Based on the recent measurements of the e^(+)e^(-)→∑^(+)∑^(-)^(-)and e^(+)e^(-)→∑^(-)∑^(-)^(+)processes by the Beijing SpectrometerⅢ(BESⅢ)collaboration,the electromagnetic form factors of the hyperon Σ^(+) a...Based on the recent measurements of the e^(+)e^(-)→∑^(+)∑^(-)^(-)and e^(+)e^(-)→∑^(-)∑^(-)^(+)processes by the Beijing SpectrometerⅢ(BESⅢ)collaboration,the electromagnetic form factors of the hyperon Σ^(+) and Σ^(-) in the timelike region are investigated using the vector-meson dominance model,where the contributions of theρ,ω,and φ mesons are taken into account.The model parameters are determined from the BESⅢexperimental data of the timelike effective form factors|G_(eff)|of the Σ^(+) and Σ^(-) baryons for center-of-mass energies from 2.3864 to 3.02 GeV.It is found that we can provide quantitative descriptions of the available data using as few as one adjustable model parameter.We then progress to an analysis of the electromagnetic form factors in the spacelike region and evaluate the spacelike form factors of the hyperons Σ^(+) and Σ^(-).The electromagnetic form factors obtained for the Σ^(+) and Σ^(-) baryons are comparable with those of other model calculations.展开更多
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
Inelastic electron scattering form factors has been calculated for different parity for the two （C3） transitions of 14^N for （5.83MeV） （f^π, T = 20） level and, （5.106MeV） （f^π, T = 30） level in the frame w...Inelastic electron scattering form factors has been calculated for different parity for the two （C3） transitions of 14^N for （5.83MeV） （f^π, T = 20） level and, （5.106MeV） （f^π, T = 30） level in the frame work of shell model. The model space wave functions are generated by using the Cohen-Kurath （CK） interaction, where 4He is assumed as a core and ten nucleons are distributed over the lp-shell which forms the model space. Core-polarization effects （CP） （the effects from outside lp-shell model space） are included through the first order perturbation theory. The core-polarization effects increase the form factor to be up near the experimental data which are not sufficient to give a good comparison with the calculating data.展开更多
We study the nucleon form factors and the nucleon-△（1232） transitions in a framework of hypercentral constituent quark model. The pion meson cloud effect is taken into account explicitly. Our results show that the ...We study the nucleon form factors and the nucleon-△（1232） transitions in a framework of hypercentral constituent quark model. The pion meson cloud effect is taken into account explicitly. Our results show that the pion cloud contributes substantially to the nucleon form factors as well as to the helicity amplitudes of △（1232）, and it gives an improved agreement compared to the experimental.展开更多
This study investigates the form factors and impact parameter space parton distribution functions of the p meson derived from the generalized parton distributions within the Nambu-Jona-Lasinio model framework,employin...This study investigates the form factors and impact parameter space parton distribution functions of the p meson derived from the generalized parton distributions within the Nambu-Jona-Lasinio model framework,employing a proper time regularization scheme.We compare the charge G_(C),magnetic G_(M),and quadrupole G_(Q) form factors with latice data.The dressed form factors,G_(C)^(D) and G_(M)^(D),exhibit good agreement with latice results;however,G_(Q)^(D) is found to be harder than what is observed in latice calculations.The Rosenbluth cross section for elastic electron scattering on a spin-one particle can be expressed through the structure functions A(Q^(2))and B(Q^(2)).Additionally,the tensor polarization T_(20)(Q^(2),θ)can also be formulated in terms of these form factors.We analyze the structure functions A(Q2),B(Q2)and tensor polarization function T2o(Q2,);our findings quantitatively align with predicted values across various limits.In impact parameter space,we examine parton distribution functions along with their dependence on longitudinal momentum fraction x and impact parameter b+.The width distributions in impact parameter space reveal that the range of the charge distribution q_(C)(x,b_(⊥)^(2))is the most extensive.In contrast,the transverse magnetic radius falls within a moderate range,while the quadrupole distribution q_(Q)(x,b_(⊥)^(2))demonstrates the narrowest extent.展开更多
The total cross sections of the process e^(+)e^(−)→Λ^(+)_(c)Λ_(c)−close to the threshold are calculated within the vector meson dominance model.It is found that the theoretical results can describe the current expe...The total cross sections of the process e^(+)e^(−)→Λ^(+)_(c)Λ_(c)−close to the threshold are calculated within the vector meson dominance model.It is found that the theoretical results can describe the current experimental measurements.The nontrivial near-threshold energy dependence of the total cross sections of the processe^(+)e^(−)→Λ^(+)_(c)Λ_(c)−can be well reproduced by considering the contributions from charmonium-like states and the Coulomb factor.In particular,the results for the angular distribution parameters about the differential cross section are consistent with the experiments from the BESIII Collaboration.In addition,the relative phase of the electromagnetic form factors is given,and the spin polarization ofΛ_(c)^(+)is predicted at center-mass energy.It is hopeful that this work will provide a new perspective on the characteristics of the charmed baryonΛ_(c)^(+).展开更多
This study is devoted to calculating the form factors of B_(c)→D_(*),B_(c)→D,B_(c)→D_(s)^(*),and B_(c)→D_(s)transitions in the framework of three-point QCD sum rules.At the QCD side,the contributions of<qq>,...This study is devoted to calculating the form factors of B_(c)→D_(*),B_(c)→D,B_(c)→D_(s)^(*),and B_(c)→D_(s)transitions in the framework of three-point QCD sum rules.At the QCD side,the contributions of<qq>,<qg_(s)σG_(q)>,<g_(s)^(2)G^(2)>,<g^(3)f_(abc)G^(3)>,and<qq><g_(s)^(2)G^(2)>are taken into account.With the obtained form factors,the decay widths and branching ratios of several two-body nonleptonic decay processes,B_(c)→η_(c)D_(*),η_(c)D,J/ψD_(*),J/ψD,η_(c)D_(s)^(*),η_(c)D_(s),J/ψD_(s)^(*),and J/ψD_(s),are predicted.These results on the form factors and decay properties of the B_(c)meson provide useful information for us to study the heavy-quark dynamical behavior.展开更多
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
We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pio...We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pion within the frame work of hadronic operator. To achieve this, we consider a slightly deformed curve deviating from a straight line and construct a set of differential equations by comparing them to the equation determining charged pion wave function in a straight line case. By solving these equations, we employ the Fourier transform of these wave functions.展开更多
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
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
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
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
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
基金supported by the National Natural Science Foundation of China(Grant Nos.11875122,12175025,and 12147102)Tongling University Talent Program(Grant No.R23100)。
文摘In this paper,we study the ρ-meson electromagnetic form factors(EMFFs)within the framework of the light-front quark model.The physical form factors G_(C,M,Q)(Q^(2))of the ρ-meson,as well as the charged square radius<r^(2)>,the magnetic moment μ,and the quadrupole moment Q,are calculated,which describe the behaviors of EMFFs at zero momentum transfer.Using the type-Ⅱ replacement,we find that the zero-mode does contribute zero to the matrix element S_(00)^(+).It is found that the“M→M_(0)”replacement improves the angular condition remarkably,which permits different prescriptions of ρ-meson EMFFs to give the consistent results.The residual tiny violation of angular condition needs other explanations beyond the zero-mode contributions.Our results indicate that the relativistic effects or interaction internal structure are weaken in the zero-binding limit.This work is also applicable to other spin-1 particles.
基金Supported by the Fundamental Research Funds for the Central Universities under Grant No.CDJZR10100023
文摘In the paper, we apply the kT factorization approach to deal with the B8 → fofo（980） transition form factors in the large recoil regions, i.e. the small q2 regions. For the purpose, we adopt the B-meson wave-functions ЖB, ЖB and that include the three-Fock states contributions to do our discussion. Although the scalar meson fo（980） is widely perceived as the 4-quark bound state （scenario 2）, but the distribution amplitudes of 4-quark states are still unknown to us, so we adopt 2-quark model （scenario 1） for scalar meson fo（980） in our discussion. By varying the B-meson wave-function parameters within their reasonable regions, we obtain Fo（0） = F＋（0） = 0.20 ± 0.02, FT（O） = 0.24 4± 0.02. Our present results for these form factors are consistent with the light-cone sum rule results obtained in the literature.
基金The project supported by the Natural Science Foundation of Hebei Province of China under Grant No. A2005000535
文摘The nucleon electromagnetic form factors are investigated within a simple diquark-quark model using the light-front formalism. In this model, baryon is described as a bound state of one quark and one clustering diquark. The calculational results are compared with the experimental ones. We also regard the quarks in a baryon as pointlike constituent quarks.
文摘We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ～ 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state.It may be an effective approach to study the form factor of proton in media.
基金The project supported by the Science Foundation of Chinese Academy of Engineering Physics under Contract No.42103 and for Research Doctor Subsidizes (2001)
文摘Based on relativistic constituent quark (RCQ) model, the electric and magnetic form factors are analyzed. The ratio of the two form factors for the proton , which is an image of its charge and magnetization distributions, is calculated in the light-front formulism of RCQ model. Recently, this ratio was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the polarization technique. The new data presented span the range and are well described by a linear Q<SUP>2</SUP> fit. Also, the ratio reaches a constant value while Q<SUP>2</SUP> becomes larger than 2 (GeV)<SUP>2</SUP>. Our calculation results are presented and appear to be consistent with the experimental ones.
基金partly supported by the National Natural Science Foundation of China under Grant Nos.12075288,11735003,and 11961141012。
文摘Based on the recent measurements of the e^(+)e^(-)→∑^(+)∑^(-)^(-)and e^(+)e^(-)→∑^(-)∑^(-)^(+)processes by the Beijing SpectrometerⅢ(BESⅢ)collaboration,the electromagnetic form factors of the hyperon Σ^(+) and Σ^(-) in the timelike region are investigated using the vector-meson dominance model,where the contributions of theρ,ω,and φ mesons are taken into account.The model parameters are determined from the BESⅢexperimental data of the timelike effective form factors|G_(eff)|of the Σ^(+) and Σ^(-) baryons for center-of-mass energies from 2.3864 to 3.02 GeV.It is found that we can provide quantitative descriptions of the available data using as few as one adjustable model parameter.We then progress to an analysis of the electromagnetic form factors in the spacelike region and evaluate the spacelike form factors of the hyperons Σ^(+) and Σ^(-).The electromagnetic form factors obtained for the Σ^(+) and Σ^(-) baryons are comparable with those of other model calculations.
基金Supported by the National Natural Science Foundation of China(31271658)National Key Research and Development Program of China(2016YFD0300306)
文摘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.
文摘Inelastic electron scattering form factors has been calculated for different parity for the two （C3） transitions of 14^N for （5.83MeV） （f^π, T = 20） level and, （5.106MeV） （f^π, T = 30） level in the frame work of shell model. The model space wave functions are generated by using the Cohen-Kurath （CK） interaction, where 4He is assumed as a core and ten nucleons are distributed over the lp-shell which forms the model space. Core-polarization effects （CP） （the effects from outside lp-shell model space） are included through the first order perturbation theory. The core-polarization effects increase the form factor to be up near the experimental data which are not sufficient to give a good comparison with the calculating data.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10475088 and 90103020, the CAS Knowledge Innovation Project under Grant No. KC2-SW-N02, and the Institute of Theoretical Physics The support from the Center of Theoretical Nuclear Physics, Lanzhou National Laboratory of Heavy Ion Accelerator is appreciated. 0ne of authors （Y.B. Dong） thanks the Department of Physics, Genova University for the hospitality. Authors are grateful to the discussions with M.M. Giannini and Santopinto.
文摘We study the nucleon form factors and the nucleon-△（1232） transitions in a framework of hypercentral constituent quark model. The pion meson cloud effect is taken into account explicitly. Our results show that the pion cloud contributes substantially to the nucleon form factors as well as to the helicity amplitudes of △（1232）, and it gives an improved agreement compared to the experimental.
基金Supported by the Scientific Research Foundation of Nanjing Institute of Technology(YKJ202352)the Natural Science Foundation of Jiangsu Province,China(BK20191472),and the China Postdoctoral Science Foundation(2022M721564)。
文摘This study investigates the form factors and impact parameter space parton distribution functions of the p meson derived from the generalized parton distributions within the Nambu-Jona-Lasinio model framework,employing a proper time regularization scheme.We compare the charge G_(C),magnetic G_(M),and quadrupole G_(Q) form factors with latice data.The dressed form factors,G_(C)^(D) and G_(M)^(D),exhibit good agreement with latice results;however,G_(Q)^(D) is found to be harder than what is observed in latice calculations.The Rosenbluth cross section for elastic electron scattering on a spin-one particle can be expressed through the structure functions A(Q^(2))and B(Q^(2)).Additionally,the tensor polarization T_(20)(Q^(2),θ)can also be formulated in terms of these form factors.We analyze the structure functions A(Q2),B(Q2)and tensor polarization function T2o(Q2,);our findings quantitatively align with predicted values across various limits.In impact parameter space,we examine parton distribution functions along with their dependence on longitudinal momentum fraction x and impact parameter b+.The width distributions in impact parameter space reveal that the range of the charge distribution q_(C)(x,b_(⊥)^(2))is the most extensive.In contrast,the transverse magnetic radius falls within a moderate range,while the quadrupole distribution q_(Q)(x,b_(⊥)^(2))demonstrates the narrowest extent.
基金Partly supported by the National Key R&D Program of China(2023YFA1606703)the National Natural Science Foundation of China(12075288,12435007,12361141819)the Youth Innovation Promotion Association CAS。
文摘The total cross sections of the process e^(+)e^(−)→Λ^(+)_(c)Λ_(c)−close to the threshold are calculated within the vector meson dominance model.It is found that the theoretical results can describe the current experimental measurements.The nontrivial near-threshold energy dependence of the total cross sections of the processe^(+)e^(−)→Λ^(+)_(c)Λ_(c)−can be well reproduced by considering the contributions from charmonium-like states and the Coulomb factor.In particular,the results for the angular distribution parameters about the differential cross section are consistent with the experiments from the BESIII Collaboration.In addition,the relative phase of the electromagnetic form factors is given,and the spin polarization ofΛ_(c)^(+)is predicted at center-mass energy.It is hopeful that this work will provide a new perspective on the characteristics of the charmed baryonΛ_(c)^(+).
基金Supported by the National Natural Science Foundation(12175068)Natural Science Foundation of HeBei Province(A2024502002)。
文摘This study is devoted to calculating the form factors of B_(c)→D_(*),B_(c)→D,B_(c)→D_(s)^(*),and B_(c)→D_(s)transitions in the framework of three-point QCD sum rules.At the QCD side,the contributions of<qq>,<qg_(s)σG_(q)>,<g_(s)^(2)G^(2)>,<g^(3)f_(abc)G^(3)>,and<qq><g_(s)^(2)G^(2)>are taken into account.With the obtained form factors,the decay widths and branching ratios of several two-body nonleptonic decay processes,B_(c)→η_(c)D_(*),η_(c)D,J/ψD_(*),J/ψD,η_(c)D_(s)^(*),η_(c)D_(s),J/ψD_(s)^(*),and J/ψD_(s),are predicted.These results on the form factors and decay properties of the B_(c)meson provide useful information for us to study the heavy-quark dynamical behavior.
基金Supported by the National Natural Science Foundation of China(12065014,12247101)the Natural Science Foundation of Gansu province(22JR5RA266)We acknowledge the West Light Foundation of the Chinese Academy of Sciences(21JR7RA201)。
文摘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.
文摘We estimate the electromagnetic form factor of the transverse part of cross section σTand provide a correction for the electromagnetic form factor of the longitudinal component of cross section σLfor the charged pion within the frame work of hadronic operator. To achieve this, we consider a slightly deformed curve deviating from a straight line and construct a set of differential equations by comparing them to the equation determining charged pion wave function in a straight line case. By solving these equations, we employ the Fourier transform of these wave functions.
基金Supported by the National Natural Science Foundation of China (11975241)。
文摘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.
基金Supported by National Natural Science Foundation of China(10975146,11035006,11261130,11165005)DFGthe NSFC through funds provided to the Sino-Germen CRC 110"Symmetries and the Emergence of Structure in QCD"
文摘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.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11822508, 11847612, and 11935013)the Chinese Academy of Sciences (CAS) Hundred-Talent Programthe Key Research Program of Frontier Sciences of CAS
文摘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.
基金partly supported by the National Natural Science Foundation of China (12075288, 12135007, 11735003, 11961141012)partly supported by the Youth Innovation Promotion Association CAS
文摘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.
文摘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.
