32 research outputs found
Polarization effects in the reaction and determination of the meson form factors in the time--like region
The electron positron annihilation reaction into four pion production has
been studied, through the channel . The
differential (and total) cross sections and various polarization observables
for this reaction have been calculated in terms of the electromagnetic form
factors of the corresponding current. The elements of the
spin--density matrix of the meson were also calculated. Numerical
estimations have been done, with the help of phenomenological form factors
obtained in the space--like region of the momentum transfer squared and
analytically extended to the time-like region.Comment: 19 pages, 2 figures, to appear in Phys Rev
Polarization effects in and determination of time like deuteron form factors
Polarization effects in the reaction have been
investigated for the case of longitudinally polarized electron beam and
arbitrary polarization of the produced deuteron, with the aim of a
determination of the time-like complex deuteron electromagnetic form factors.
General expressions of polarization observables are derived and numerical
estimations have been carried out by means of various models of deuteron
electromagnetic form factors, for kinematical conditions near threshold.Comment: 19 pages, 3 figure