Examination of the production of an isotensor dibaryon in the pp→ppπ+π- reaction

Abstract

The quasifree pp→ppπ+π- reaction has been measured by means of pd collisions at Tp=1.2GeV using the WASA detector setup at COSY enabling exclusive and kinematically complete measurements. Total and differential cross sections have been extracted for the energy region Tp=1.08-1.36 GeV (s=2.35-2.46GeV) covering thus the regions of N∗(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange as well as isospin relations based on the pp→ppπ0π0 data underpredict substantially the measured total cross section. The calculations are also at variance with specific experimental differential cross sections. An isotensor ΔN dibaryon resonance with I(JP)=2(1+) produced associatedly with a pion is able to overcome these deficiencies. Such a dibaryon was predicted by Dyson and Xuong [Phys. Rev. Lett. 13, 815 (1964)PRLTAO0031-900710.1103/PhysRevLett.13.815] and more recently calculated by A. Gal and H. Garcilazo [Nucl. Phys. A 928, 73 (2014)NUPABL0375-947410.1016/j.nuclphysa.2014.02.019]. © 2019 American Physical Society.