Search results for "form factor"
showing 10 items of 261 documents
Quasielastic neutrino (antineutrino) reactions in nuclei and the axial-vector form factor of the nucleon
1992
Abstract Quasielastic neutrino and antineutrino reactions in nuclei are studied to investigate the effect of the nuclear medium on the determination of axial dipole mass M A in nuclei. The calculations are done in the local density approximation and various nuclear effects like Pauli blocking, Fermi motion of nucleons and strong renormalization effects in the spin-isospin channel are taken into account. The nuclear effects are found to be quite large at low q 2 , but the data in this region are too meagre to influence the determination of M A . The experimental data on differential and total cross sections are found to be consistent with M A as determined from deuterium experiments and no c…
Neutrino Induced Charged Current 1$\pi^+$ Production At Intermediate Energies
2006
The charged current one pion production induced by $\nu_\mu$ from nucleons and nuclei like $^{12}$C and $^{16}$O nuclei has been studied. The calculations have been done for the incoherent and the coherent processes from nuclear targets assuming the $\Delta$ dominance model and take into account the effect of Pauli blocking, Fermi motion of the nucleon and renormalization of $\Delta$ properties in a nuclear medium. The effect of final state interactions of pions has been taken into account. The theoretical uncertainty in the total cross sections due to various parameterizations of the weak transition form factors used in literature has been studied. The numerical results for the total cross…
Nucleon strangeness and unitarity
1996
The strange-quark vector current form factors of the nucleon are analyzed within the framework of dispersion relations. Particular attention is paid to contributions made by $K\bar{K}$ intermediate states to the form factor spectral functions. It is shown that, when the $K\bar{K}\to N\bar{N}$ amplitude is evaluated in the Born approximation, the $K\bar{K}$ contributions are identical to those arising from a one-loop calculation and entail a serious violation of unitarity. The mean square strangeness radius and magnetic moment are evaluated by imposing unitarity bounds on the kaon-nucleon partial wave amplitudes. The impact of including the kaon's form factor in the dispersion integrals is a…
Measurement of thee+e−→pp¯cross section in the energy range from 3.0 to 6.5 GeV
2013
The e^+e^−→pp cross section and the proton magnetic form factor have been measured in the center-of-mass energy range from 3.0 to 6.5 GeV using the initial-state radiation technique with an undetected photon. This is the first measurement of the form factor at energies higher than 4.5 GeV. The analysis is based on 469 fb^(−1) of integrated luminosity collected with the BABAR detector at the PEP-II collider at e+e− center-of-mass energies near 10.6 GeV. The branching fractions for the decays J/ψ→pp and ψ(2S)→pp have also been measured.
The scalar form factor in the exclusive semi-leptonic decay of B→π+τ+ντ
1990
Abstract Using current algebra and the soft pion theory we derive the Callan-Treiman type relation ƒ(t max )≅ ƒ B ƒ π for the scalar form factor in the exclusive semi-leptonic decay B→π+τ+ντ.
A modified born term model for π± Δ electroproduction
1974
An electric Born type model is used to describeπ±Δ electroproduction at high energies. The electric pion form factor is taken from VDM; the contact term form factor and theΔ form factor are set equal to the proton form factor (or equal to zero) which is left as an arbitrary parameter, and is determined by a fit of the model to the recentπ+δ0 andπ−Δ++ electroproduction data.
Measurement of the proton form factor by studyinge+e−→pp¯
2015
Using data samples collected with the BESIII detector at the BEPCII collider, we measure the Born cross section of e(+)e(-) -> p (p) over tilde at 12 center-of-mass energies from 2232.4 to 3671.0 MeV. The corresponding effective electromagnetic form factor of the proton is deduced under the assumption that the electric and magnetic form factors are equal (vertical bar G(E)vertical bar = vertical bar G(M)vertical bar). In addition, the ratio of electric to magnetic form factors, vertical bar G(E)/G(M)vertical bar, and vertical bar G(M)vertical bar are extracted by fitting the polar angle distribution of the proton for the data samples with larger statistics, namely at root s = 2232.4 and 240…
First measurement of the polarisation transfer on the proton in the reactions $$H(\vec e,e'\vec p)$$ and $$D(\vec e,e'\vec p)$$
1995
The measurement of the polarisation transfer to the proton in the reactions\(H(\vec e,e'\vec p)\) and\(D(\vec e,e'\vec p)\) performed with longitudinally polarised electrons in quasi-free kinematics is presented. The coincidence measurement was executed atQ2≈8fm−2 using the 855 MeV, c.w. beam of the Mainz Microtron MAMI. The recoil polarisation was determined by means of a carbon analyser. The experiment shows that the binding of the nucleon does not modify the polarisationPx of the recoil proton within an error ofΔPx/Px≈10%. The measured polarisation agrees with recent theoretical predictions. Implications for the measurement of the electric form factor of the neutron using the\(D(\vec e,e…
Relativistic corrections to the elastic electron scattering fromPb208
1976
In the present work we have calculated the differential cross sections for the elastic electron scattering from $sup 208$Pb using the charge distributions resulting from various corrections. The point proton and neutron mass distributions have been calculated from the spherical wave functions for $sup 208$Pb obtained by Kolb et al. The relativistic correction to the nuclear charge distribution coming from the electromagnetic structure of the nucleon has been accomplished by assuming a linear superposition of Gaussian shapes for the proton and the neutron charge form factor. Results of this calculation are quite similar to an earlier calculation by Bertozzi et al., who have used a different …
On the determination of the proton RMS-radius from electron scattering data
1975
It is shown that the proton rms radius should be determined from fitting a polynomial of second order to the low-q 2 form factors. The commonly used polynomial of first order yields radius values which are too small. The proton rms radius has been redetermined from an analysis of the electron scattering data measured at three laboratories. The best fit value is 〈r E 2 〉1/2=0.87±0.02 fm.