832 research outputs found
Pionic Degrees of Freedom in Atomic Nuclei and Quasielastic Knockout of Pions by High-Energy Electrons
The nonlinear model of pionic condensate in nuclei by G. Preparata can be
efficiently verified by investigation of the quasielastic knockout process of
pions out of nuclei by high energy electrons. First, a momentum distribution
(MD) of the collective pions has a bright maximum at q=0.3 Gev.Second the
excitation spectrum of a recoil nucleus is concentrated at low energies E
lesser than 1MeV. The results for the pion knockout from mesonic clouds of
individual nucleons are absolutely different. The latter results are presented
both for pion and rho-meson clouds localized on nucleons.Comment: 13 pages, 3 figure
One-sided approximation in L of the characteristic function of an interval by trigonometric polynomials
The value of the best one-sided integral approximation of the characteristic function of the interval (-h, h) by trigonometric polynomials of given degree is found for any 0 < h ≤ π. © 2013 Pleiades Publishing, Ltd
Role of the rho meson in the description of pion electroproduction experiments at JLab
We study the p(e,e' pi+)n reaction in the framework of an effective
Lagrangian approach including nucleon, pi and rho meson degrees of freedom and
show the importance of the rho-meson t-pole contribution to sigmaT, the
transverse part of cross section. We test two different field representations
of the rho meson, vector and tensor, and find that the tensor representation of
the rho meson is more reliable in the description of the existing data. In
particular, we show that the rho-meson t-pole contribution, including the
interference with an effective non-local contact term, sufficiently improves
the description of the recent JLab data at invariant mass W less 2.2 GeV and Q2
less 2.5 GeV2/c2. A ``soft'' variant of the strong piNN and rhoNN form factors
is also found to be compatible with these data. On the basis of the successful
description of both the sigmaL and sigmaT parts of the cross section we discuss
the importance of taking into account the sigmaT data when extracting the
charge pion form factor Fpi from sigmaL.Comment: 23 pages, 6 figures, accepted for publication in Phys. Rev.
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