Single-Pion Production inπ−pInteractions at 2.26 GeV/c

Abstract

We present an analysis of inrN final states obtained from ir~p interactions at 2.26 GeV/c. Strong p production is present in both final states. In addition, significant nucleon isobar production is observed. We observed the following cross sections: <T(it~ir a p) = 3.77±0.13 mb, cr(7r~7r + ») = 5.67±0.17 mb, <r{p~p) -2.19 ±0.09 mb, cr(A + (1236)7r-) = 0.30±0.10 mb, <r(iV 0 (1650)7r 0 ) = 0.49 ±0.07 mb, a( P°n )= 2.89±0.11 mb, (r(A-(1236)7r + ) = 0.11±0.06 mb, o-(iV + (1470)x-) = 0.24±0.06 mb, and <r(N + (1650)ir) = 0.45±0.05 mb. The spin-density matrix elements are determined for the p° by interpreting the p° asymmetry as an interference between the resonant P wave and a T = 0 S wave. A search for the e° in the ir + ir~n final state failed to yield a direct observation of this effect.

Implications of inelastic rescatterings for pion double charge exchange on nuclei

“…(3) The experimental distributions on the two-pion mass (M or M 2 ) for incident momentum values of 1.343 [10], 1.59 [14], 2.26 [15], and 4 GeV /c [16] are compared with the calculated ones (see Figs. 7-10).…”

Study of the reaction π−p↑ → π−π+n on a polarized proton target at 17.78 GeV/c. Experiment and amplitude analysis

“…As a consequence there should be a scalar-isoscalar 2 resonance in S-wave with similar mass and width. In order to estimate its parameters we plotted the unnormalised intensities of S and L-waves using the normalized amplitudes from our model-dependent analysis and the mass dependence of the cross section obtained at 2.26 GeV/c in 4π-geometry experiment [6]. The unnormalised amplitudes were fitted by relativistic Breit-Wigner formula with constant incoherent background:…”

“…They allow to study the dynamics of the processes as well as the pion-pion interaction. Up to now a number of experiments which study production of pions by pions were fulfilled on unpolarized proton targets [1][2][3][4][5][6][7] in the intermediate energy region. Their results showed the predominant role of the one pion exchange (OPE) and noticeable effects of absorption.…”

Differences of masses and widths of the charged and neutral $\rho(770)$, $\rho(1450)$, $\rho(1700)$ mesons from data on electro-weak processes

“…In the past the determination of ρ -meson parameters from processes including the pion-proton interactions π ± p → π π n [4,5], the proton-antiproton annihilation pp → π + π − π 0 [6,7], e + e − → π + π − π 0 annihilation [2,8], τ −lepton decay processes [9] has been performed predominantly by Breit-Wigner formalism. Such formalism yields high experimental uncertainties (see Tab.…”