What new information about the microscopic quark structure of meson-baryon degrees of freedom in nucleons can be deduced from data on quasielastic pion knockout?

10.1007/s11450-008-3016-1

“…As in the previous studies of our group that were devoted to pions, kaons, and rho mesons [1,4], the wave function Φ b 1 (e, ξ) is taken in the harmonicoscillator form…”

“…Here, β π is the meson-radius parameter, which, by virtue of the fact that the b 1 meson is considered here as a pion excited state of orbital angular momentum L = 1, is set to the value of the corresponding parameter for the pion-state wave function [1,4], and the function Φ M (ξ, β π ) is represented in the form…”

“…In the previous studies of our group [1][2][3][4][5][6][7], it was shown that, in charged-pion electroproduction, the t-channel pole diagram is dominant at rather high values of the square of the virtual-photon momentum, Q 2 = −q 2 = 1-3 (GeV/c) 2 . This fact made it possible to introduce the concept of quasielastic pion knockout from a nucleon as a development of the concept of the nonrelativistic quasielastic knockout of constituents from nuclei.…”

“…One version of the quark approach relies on the model of a 3 P 0 -wave scalarqq fluctuation [10][11][12][13][14][15][16]. A microscopic technique for projecting the wave function for the q 3 qq multiquark configuration in the nucleon onto channels of the virtual decay of pions, kaons [1,4], and rho mesons [3] was developed on the basis of the 3 P 0 -wave model. The known value of the phenomenological pion-nucleon coupling constant g πN N was used to determine the constant g s of the scalar fluctuation of the QCD vacuum in the 3 P 0wave model [11] and to calculate the pion momentum distributions for the B = N , ∆(1232), N * * 1/2 + (1440), and N * 1/2 -(1535) channels [1,4]; the kaon momentum distributions for the Y = Λ and Σ channels [1]; and the rho-meson momentum distributions for the B = N channel [3].…”

“…A microscopic technique for projecting the wave function for the q 3 qq multiquark configuration in the nucleon onto channels of the virtual decay of pions, kaons [1,4], and rho mesons [3] was developed on the basis of the 3 P 0 -wave model. The known value of the phenomenological pion-nucleon coupling constant g πN N was used to determine the constant g s of the scalar fluctuation of the QCD vacuum in the 3 P 0wave model [11] and to calculate the pion momentum distributions for the B = N , ∆(1232), N * * 1/2 + (1440), and N * 1/2 -(1535) channels [1,4]; the kaon momentum distributions for the Y = Λ and Σ channels [1]; and the rho-meson momentum distributions for the B = N channel [3]. The pion momentum distribution obtained in this way for the B = N channel has a pronounced maximum in the region around |k| ∼ 0.1 GeV/c and agrees fairly well with available experimental data on p(e, e π + )n quasielastic longitudinal cross sections [8], while the longitudinal cross section calculated for quasielastic kaon electroproduction complies with its experimental counterpart [17,18].…”