New data on Δ++-baryon production in annihilation at rest

Probing the deuteron structure at small NN distances by antiproton-deuteron annihilation

“…(3) was calculated at a very small initial antiproton energy satisfying to the experimental resolution and normalized by the total number of events, N, corresponding to experimental measurements. This spectrum dN/dm π + π − and the experimental data are presented in Fig.2, the parameters w ρ , w f 2 , w 0 and R 2 π were found by fitting the OBELIX experimental data [11] for dN/dm π + π − , they are w ρ = 1.2, w f 2 = 1.35, w 0 = 35.0 and R 2 π ≃ 2. (F eV /c) −2 .…”

“…[10]). New data obtained by this experiment [11] show the very interesting behavior of the π − π − system invariant mass distribution in reactionpd → 2π − π + p. In this paper we concentrate on detailed analysis of this annihilation channel. We show also that some enhancement in the spectrum over the invariant mass of two π − -mesons observed by OBELIX can be explained by the possible existence of a ∆ − ∆ component in the deuteron.…”

“…It was parametrized by a form that resulted in a satisfactory description of the experimental data for dN/dm π + π − . According to the OBELIX data [11] the spectrum dN/dm π + π − has a resonance-like shape, see Fig.2, corresponding to the possible production of ρmeson at m π + π − ≃ 0.77(GeV /c 2 ) and f 2 -meson at m π + π − = 1.26(GeV /c 2 ). The dependence of | fp n→2π − π + (s 3π , s 2π , t 1 ) | 2 on sp n = s 3π can be found using the model of the Reggeized meson exchange in the t-channel of the reaction π + n → π + π − p, where t > 0. and t = (p n − p p ) 2 = (p n + pp) 2 ≡ sp n = s 3π .…”

“…(5) into eq. (4) one can calculate the spectrum dN/dm 2π − which is presented in Fig.3 (the dashed curve) together with the experimental data [11]. Now, consider the problem related to the possible existence of baryon resonances in a deuteron.…”

“…(3) one can calculate the spectrum dσ/dm π + π − . Experimental measurements of this spectrum were performed at rest and presented in [11]. Therefore, the spectrum given by eq.…”