Relativistic instant-form approach to the structure of two-body composite systems: Nonzero spin

Abstract

The relativistic approach to electroweak properties of twoparticle composite systems developed in Ref.[1] is generalized here to the case of nonzero spin. In developed technique the parametrization of matrix elements of electroweak current operators in terms of form factors is a realization of the Wigner-Eckart theorem on the Poincaré group and form factors are reduced matrix elements. The ρ meson charge form factor is calculated as an example. * Electronic address: krutov@ssu.samara.ru † Electronic address: troitsky@theory.sinp.msu.ru

Construction of form factors of composite systems by a generalized Wigner-Eckart theorem for the Poincaré group

“…The modified impulse approximation, which has the physical content of the relativistic impulse approximation, was formulated in [4], [5] in terms of reduced matrix elements. This approximation conserves the Lorentz covariance of the electromagnetic current and the current conservation law.…”

CP-violation hypothesis and the relativistic electromagnetic structure of nucleons

“…[17]) which follows from the general method of relativistic invariant parameterization for local operator matrix elements proposed by Cheshkov and Shirokov [18]. In fact, this parametrization is a realization of the Wigner-Eckart theorem for the Poincaré group and so it enables one for given matrix element of arbitrary tensor dimension to separate the reduced matrix elements (form factors) which are invariant under the Poincaré group.…”

Pion form factor in time like region in a framework of relativistic composite quark model

“…Among the most successful modern approaches to the description of the pion electromagnetic form factor in terms of quark degrees of freedom it is necessary to note ones based on ADS/CFT duality [5,6] and the Poincaré-invariant quantum mechanics (PIQM) [8,9,10]. The both of approaches gives a good description of form factor in space-like region.…”