Reaction of two pion production pd → pdππ in the resonance region

Yuriy Uzikov,Nurbek Tursunbayev

doi:10.1051/epjconf/201920408010

Abstract

The ANKE@COSY data on the reaction of two-pion production in the GeV region are analyzed within the theoretical model by Platonova and Kukulin. The model includes excitation of the dibaryon resonance DIJ = D03(2380) with the spin J = 3 and isospin I = 0 observed by the WASA@COSY in the reaction pn → dπ0π0, and its decay D03 → D12 + π → d + π + π, where D12(2150) is another dibaryon resonance. Distributions on the invariant masses of the final dππ and ππ systems are calculated.

Highlights

Search for dibaryon resonances in two-nucleon systems has a long history
At present one of the most realistic candidate to dibaryon is the resonance DIJ = D03 observed by the WASA@COSY [2] in the total cross section of the reaction of two-pion production pn → dπ0π0, where I = 0 is the isospin and J = 3 is the total angular momentum of this resonance
In a pure hadronic picture with the nucleon, ∆(1232)-isobar and pion degrees of freedom, it is possible to get a resonance state in the πN∆ system [4,5,6], with rather narrow width if one assumes excitation of the dibaryon resonance D12 in the N∆-interaction. As it was shown recently by Niskanen [7], the bound ∆∆-system has the narrow width if one takes into account that a part of the energy of this system is assigned to internal motion of two ∆’s and, cannot be used for decay of the ∆-isobars

Summary

Introduction

Search for dibaryon resonances in two-nucleon systems has a long history (for review see [1]). The ABC-type effect was observed in [11] in the distribution of the invariant mass of two final pions Mππ Two mechanisms of this reaction involving excitation of the Roper resonance N∗(1440) and two ∆-isobars in one-loop diagrams depicted in Fig. 1 were studied in [12]. We modify this model by inclusion of the σ-meson exchange between the proton and deuteron and apply it to the process pd → pdππ (Fig. 2) As it was found in [10], the ABC effect in the reaction pn → dπ0π0 can be explained if an additional decay mechanism is included, D03 → dσ → dπ0π0, and partial restoration of the chiral symmetry in the D03 dibaryon is assumed. Since not all required partial widths are known from the experiment [13] and theoretical analysis in hadronic picture [14] and quark model [3], we discuss mainly the shapes of the distributions over the invariant masses of the final dππ and ππ systems

The model

Numerical results and discussion

Conclusion