44 research outputs found
Q^2-evolution of nucleon-to-resonance transition form factors in a QCD-inspired vector-meson-dominance model
We adopt the vector-meson-dominance approach to investigate Q^2-evolution of
N-R transition form factors (N denotes nucleon and R an excited resonance) in
the first and second resonance regions. The developed model is based upon
conventional NR\gamma-interaction Lagrangians, introducing three form factors
for spin-3/2 resonances and two form factors for spin-1/2 nucleon excitations.
Lagrangian form factors are expressed as dispersionlike expansions with four or
five poles corresponding to the lowest excitations of the mesons \rho(770) and
\omega(782). Correct high-Q^2 form factor behavior predicted by perturbative
QCD is due to phenomenological logarithmic renormalization of electromagnetic
coupling constants and linear superconvergence relations between the parameters
of the meson spectrum. The model is found to be in good agreement with all the
experimental data on Q^2-dependence of the transitions N-\Delta(1232),
N-N(1440), N-N(1520), N-N(1535). We present fit results and model predictions
for high-energy experiments proposed by JLab. Besides, we make special emphasis
on the transition to perturbative domain of N-\Delta(1232) form factors.Comment: 22 pages, 22 PS figures, REVTeX 4; v2: +3 refs, minor editorial
change
Quantum geometrodynamics of the Bianchi IX model in extended phase space
A way of constructing mathematically correct quantum geometrodynamics of a
closed universe is presented. The resulting theory appears to be
gauge-noninvariant and thus consistent with the observation conditions of a
closed universe, by that being considerably distinguished from the conventional
Wheeler - DeWitt one. For the Bianchi-IX cosmological model it is shown that a
normalizable wave function of the Universe depends on time, allows the standard
probability interpretation and satisfies a gauge-noninvariant dynamical
Schrodinger equation. The Wheeler - DeWitt quantum geometrodynamics is
represented by a singular, BRST-invariant solution to the Schrodinger equation
having no property of normalizability.Comment: LaTeX, 18 pages, to be published in Int. J. Mod. Phys.