267 research outputs found
Polarization observables in lepton-deuteron elastic scattering including the lepton mass
Expressions for the unpolarized differential cross section and for various
polarization observables in the lepton-deuteron elastic scattering, , , , , have been obtained in one-photon-exchange
approximation, taking into account the lepton mass. Polarization effects have
been investigated for the case of a polarized lepton beam and polarized
deuteron target which can have vector or tensor polarization. Numerical
estimations of the lepton mass effects have been done for the unpolarized
differential cross section and for some polarization observables and applied to
the case of low energy muon deuteron elastic scattering.Comment: 29 pages, 6 figur
Experimental constraint on the meson form factors in the time--like region
The annihilation reaction is considered.
The constraint on time-like -meson form factors from the measurement done
by the BaBar collaboration at GeV is analyzed.Comment: 10 pages 3 figure
Model independent study of massive lepton elastic scattering on the proton, beyond the Born approximation
Model independent expressions for all polarization observables in elastic scattering are obtained, taking into account the lepton mass and
including the two-photon exchange contribution. The spin structure of the
matrix element is parametrized in terms of six independent complex amplitudes,
functions of two independent kinematical variables. General statements about
the influence of the two--photon--exchange terms on the differential cross
section and on polarization observables are given. Polarization effects have
been investigated for the case of a longitudinally polarized lepton beam and
polarized nucleon in the final state.Comment: 28 pages, 3 figure
Search for evidence of two photon contribution in elastic electron proton data
We reanalyze the most recent data on elastic electron proton scattering. We
look for a deviation from linearity of the Rosenbluth fit to the differential
cross section, which would be the signature of the presence of two photon
exchange. The two photon contribution is parametrized by a one parameter
formula, based on symmetry arguments. The present data do not show evidence for
such deviation.Comment: 15 pages 3 figures More details on the fitting procedure, more
explicit explanation
Two-component model for the deuteron electromagnetic structure
We suggest a simple phenomenological parametrization for all three deuteron
electromagnetic form factors, and show that a good fit on the available data,
with a minimal number of parameters, can be obtained. The present description
of the deuteron electromagnetic structure is based on two components with
different radii, one corresponding to two nucleons separated by 2 fm,
and a standard isoscalar contribution, saturated by and mesons,
only.Comment: 5 pages, 6 fig. 2 table
Proton-antiproton annihilation into massive leptons
We extend previous calculations of polarization observables for the
annihilation reaction to the case of heavy
leptons, such as the -lepton. We consider the case when the beam and/or
the target are polarized, as well as the polarization of the outgoing leptons.
We give the dependence of the unpolarized cross section, angular asymmetry, and
various polarization observables on the relevant kinematical variables in the
center of mass and in the laboratory system, with particular attention to the
effect of the mass induced terms.Comment: 25 pages, 8 figure
General analysis and numerical estimations of polarization observables in reaction in an exclusive experimental setup
The dependence of the differential cross section and polarization observables
in the reaction on the polarizations of the proton
target and antiproton beam (the produced electron may be unpolarized or
longitudinally polarized) have been derived in a general form using hadron
electromagnetic current conservation and invariance of the hadron
electromagnetic interaction. The analysis was done for the case of an exclusive
experimental setup where the produced electron and pion are detected in
coincidence. The explicit dependence of all polarization observables on two,
from five, kinematic variables (the azimuthal angle and the
virtual-photon parameter ), have been obtained assuming
one-photon-exchange. The application to the particular case of a mechanism
which contains information on time-like proton form factors in the unphysical
region is considered in the Born approximation.Comment: arXiv admin note: substantial text overlap with arXiv:1011.401
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