Quantifying.Associations among Dimensions of Ears and Their Form Factors in Maize(Zea Mays)Using Dimensional Analysis

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.

Gravitational form factors of the proton from near-threshold vector meson photoproduction

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.

Contributions to the nucleon form factors from bubble and tadpole diagrams

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.

Deuteron electromagnetic form factors and tensor polarization observables in the framework of the hard-wall AdS/QCD model

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.

Gluon gravitational form factors of protons from charmonium photoproduction

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.

B_((s))→D^(∗∗)_((s))form factors in HQEFT and model independent analysis of relevant semileptonic decays with NP effects

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.

Neutral Pion Electromagnetic Form Factor as a Bound System of 3 + 1 Dimensional QCD

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. .

Deuteron electromagnetic form factors in transverse plane with a phenomenological Lagrangian approach

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.

On-shell methods for form factors in N = 4 SYM and their applications

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.

Electromagnetic form factors of neutron and neutral hyperons in the oscillating point of view

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.

Excited nucleon electromagnetic form factors from broken spin-flavor symmetry

A group theoretical derivation of a relation between the N→△charge quadrupole transition and neutron charge form factors is presented.

Electromagnetic form factors of Λ_c in the space-like momentum region

We studied the electromagnetic form factors （EMFFs） of Ac and the contributions of the quark and diquark currents to the EMFFs of Ac in the space-like region in the Bethe-Salpeter equation approach with instantaneous approximation. In this picture, baryon Ac can be regarded as a two-body c（ud） system. We found that for different values of parameters the contribution of quark and diquark currents to the EMFFs of Ac is very different, while their total contribution to the EMFFs of Ac is similar. The EMFFs of ∧c are similar to those of other baryons （proton,≡ , and ∑＋） with a peak at ω= 1, where ω=v＇.v is the velocity transfer between the initial state （with velocity v） and the final state （with velocity vr） of Ac.

B_(c)→J/ψhelicity form factors and the B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ))decays

In this paper,we calculate the B_(c)→J/ψhelicity form factors(HFFs)up to twist-4 accuracy by using the light-cone sum rules(LCSR)approach.After extrapolating those HFFs to the physically allowable q^(2)region,we investigate the B_(c)^(+)-meson two-body decays and semi-leptonic decays B_(c)^(+)→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),where P/V stand for light pseudoscalar and vector mesons,respectively.The branching fractions can be derived using the CKM matrix element and the B_(c)lifetime from the Particle Data Group,and we obtain B(B^(+)_(c)→J/ψπ^(+))=(0.136+0.002−0.002)%,B(B^(+)_(c)→J/ψK^(+))=(0.010+0.000−0.000)%,B(B^(+)_(c)→J/ψρ+)=(0.768+0.029−0.033)%,B(B^(+)_(c)→J/ψK^(∗+))=(0.043+0.001−0.001)%,B(B^(+)_(c)→J/ψ_(μ)+ν_(μ))=(2.802+0.526−0.675)%and B(B^(+)_(c)→J/ψτ^(+)ν_(τ))=(0.559+0.131−0.170)%.We then obtain R_(π^(+)/μ+ν_(μ))=0.048+0.009−0.012 and R_(K^(+)/π^(+))=0.075+0.005−0.005,which agree with the LHCb measured value within 1σ-error.We also obtain R_(J/ψ)=0.199+0.060−0.077,which like other theoretical predictions,is consistent with the LHCb measured value within 2σ-error.These imply that the HFFs under the LCSR approach are also applicable to the B+c meson two-body decays and semi-leptonic decays B+c→J/ψ+(P,V,ℓ^(+)ν_(ℓ)),and the HFFs obtained using LCSR in a new way implies that there may be new physics in the B_(c)→J/ψℓ^(+)ν_(ℓ)semi-leptonic decays.

An estimate of two-photon exchange effect on deuteron electromagnetic form factors

The effect of the two-photon exchange on the deuteron electromagnetic form factors is estimated based on an effective Lagrangian approach. A numerical estimate calculation of the effect is discussed. In particular, the effect on the polarization observables is analyzed.

Nucleon form factors:the space-time connection

Analyticity of nucleon form factors allows to derive sum rules which, using space-like and time-like data as input, can give unique information about behaviors in energy regions not experimentally accessible. Taking advantage from new time-like data on proton-antiproton differential cross section and hence the possibility to separate electric and magnetic form factors also in the time-like region, we verify the consistency of the asymptotic behavior predicted by the perturbative QCD for the proton magnetic form factor.

Gravitational form factors and nucleon spin structure

Nucleon scattering by the classical gravitational field is described by the gravitational （energy- momentum tensor） form factors （GFFs）, which also control the partition of nucleon spin between the total angular momenta of quarks and gluons. The equivalence principle （EP） for spin dynamics results in the identically zero anomalous gravitomagnetic moment, which is the straightforward analog of its electromagnetic counterpart. The extended EP （ExEP） describes its （approximate） validity separately for quarks and gluons and, in turn, results in equal partition of the momentum and total angular momentum. It is violated in quantum electrodynamics and perturbative quantum chromodynamics （QCD）, but may be restored in nonperturbative QCD because of confinement and spontaneous chiral symmetry breaking, which is supported by models and lattice QCD calculations. It may, in principle, be checked by extracting the generalized parton distributions from hard exclu- sive processes. The EP for spin-1 hadrons is also manifested in inclusive processes （deep inelastic scattering and the Drell-Yan process） in sum rules for tensor structure functions and parton distributions. The ExEP may originate in either gravity-proof confinement or in the closeness of the GFF to its asymptotic values in relation to the mediocrity principle. The GFFs in time-like regions reveal some similarity between inflation and annihilation.

Dirac and Pauli form factors of nucleons using nonlocal chiral effective Lagrangian

Dirac and Pauli form factors are investigated in the relativistic chiral effective Lagrangian.The octet and decuplet intermediate states are included in the one-loop calculation.The 4-dimensional regulator is introduced to deal with the divergence.Different from the non-relativistic case,this 4-dimensional regulator is generated from the nonlocal Lagrangian with the gauge link,which guarantees local gauge invariance.As a result,additional diagrams appear which ensure electric charge 1 and 0 for proton and neutron respectively.The obtained Dirac and Pauli form factors of the nucleons are all reasonable up to relatively large Q;.

Role of neutrino form factors in the energy loss rates of the pair annihilation process

The stellar energy loss rates due to the production of neutrino pairs e^(+)e^(-) → (W, Z, γ) → veve are calculated using the minimal extension of the Standard Model with the electromagnetic properties of the Dirac neutrinos, which takes the contributions of the neutrino charge radius, anapole moment, and dipole moments into account. We show that the contribution of the electron neutrino's dipole moment is small compared with that of the charge radius. The obtained results are also compared with the results obtained using the Standard Model.

Electromagnetic form factors of Σ^(+) and Σ^(-) in the vector-meson dominance model

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.

Comparative studies on nuclear elastic magnetic form factors between the relativistic and non-relativistic mean-field approaches

It is known that elastic magnetic electron scattering can be used to study the magnetic properties of nuclei and determine the outermost-shell single-particle orbitals.In this study,the magnetic form factors|F_(M)(q)|^(2)of odd-A nuclei calculated with relativistic and non-relativistic models are systematically compared.We use the relativistic mean-field(RMF)and Skyrme Hartree-Fock(SHF)models to generate single-particle wave functions and calculate the|F_(M)(q)|^(2)values of selected nuclei under relativistic and non-relativistic frameworks,respectively.Geometric factors are introduced through the spherical limit method to consider the influences of deformation,which improves the agreement between the theoretical results and experimental data.It is shown that both the models have the capability to describe the magnetic form factors in the spherical and deformed cases,and the discrepancies in|F_(M)(q)|^(2)reflect the differences in the descriptions of the single-particle orbital between the two models.