20 research outputs found
Proton charge and magnetic rms radii from the elastic scattering data
The elastic electron-proton scattering data are analysed in order to
determine proton charge and magnetic rms radii, r_E and r_M. Along with the
usual statistical error, we try to estimate a systematic error in the radii,
caused by the inadequacy of particular form factor parameterization employed.
The range of data to use in the analysis is chosen so as to minimize the total
(statistical + systematic) error. We obtain r_E = 0.912 +- 0.009 (stat) +-
0.007 (syst) fm, and r_M = 0.876 +- 0.010 (stat) +- 0.016 (syst) fm. The
cross-section data were corrected for two-photon exchange. We found that
without such corrections obtained r_E and r_M are somewhat smaller while the
quality of fit is worse.Comment: 6 pages, 4 figures. Numbers slightly changed due to discovered error
in minimization program. Sec.III revised, discussion of G_E behaviour added
On the rms-radius of the proton
We study the world data on elastic electron-proton scattering in order to
determine the proton charge rms-radius. After accounting for the Coulomb
distortion and using a parameterization that allows to deal properly with the
higher moments we find a radius of 0.895+-0.018 fm, which is significantly
larger than the radii used in the past.Comment: 9 pages, 2 figures, submitted to Phys.Lett.
Elastic electron-deuteron scattering in chiral effective field theory
We calculate elastic electron-deuteron scattering in a chiral effective field
theory approach for few-nucleon systems based on a modified Weinberg power
counting. We construct the current operators and the deuteron wave function at
next-to-leading (NLO) and next-to-next-to-leading (NNLO) order simultaneously
within a projection formalism. The leading order comprises the impulse
approximation of photons coupling to point-like nucleons with an anomalous
magnetic moment. At NLO, we include renormalizations of the single nucleon
operators. To this order, no unknown parameters enter. At NNLO, one
four-nucleon-photon operator appears. Its strength can be determined from the
deuteron magnetic moment. We obtain not only a satisfactory description of the
deuteron structure functions and form factors measured in electron-deuteron
scattering but also find a good convergence for these observables.Comment: 13 pp, elsart.cls, 4 figs, extended version, includes NNLO
corrections and more detailed discussion
A Perturbative Calculation of the Electromagnetic Form Factors of the Deuteron
Making use of the effective field theory expansion recently developed by the
authors, we compute the electromagnetic form factors of the deuteron
analytically to next-to-leading order (NLO). The computation is rather simple,
and involves calculating several Feynman diagrams, using dimensional
regularization. The results agree well with data and indicate that the
expansion is converging. They do not suffer from any ambiguities arising from
off-shell versus on-shell amplitudes.Comment: 22 pages, 8 figures. Discussion of effective range theory added,
typos correcte
Neutron charge form factor at large
The neutron charge form factor is determined from an analysis of
the deuteron quadrupole form factor data. Recent calculations, based
on a variety of different model interactions and currents, indicate that the
contributions associated with the uncertain two-body operators of shorter range
are relatively small for , even at large momentum transfer . Hence,
can be extracted from at large without undue
systematic uncertainties from theory.Comment: 8 pages, 3 figure
Poincare' Covariant Current Operator and Elastic Electron-Deuteron Scattering in the Front-form Hamiltonian Dynamics
The deuteron electromagnetic form factors, and , and the
tensor polarization , are unambiguously calculated within the
front-form relativistic Hamiltonian dynamics, by using a novel current, built
up from one-body terms, which fulfills Poincar\'e, parity and time reversal
covariance, together with Hermiticity and the continuity equation. A
simultaneous description of the experimental data for the three deuteron form
factors is achieved up to . At higher momentum transfer,
different nucleon-nucleon interactions strongly affect , , and
and the effects of the interactions can be related to -state
kinetic energy in the deuteron. Different nucleon form factor models have huge
effects on , smaller effects on and essentially none on
.Comment: 31 pages + 16 figures. Submitted to Phys. Rev.
The deuteron: structure and form factors
A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic