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

Abstract

P. ADLARSON et al. PHYSICAL REVIEW C 99, 025201 (2019) The quasifree pp → ppπ + π − reaction has been measured by means of pd collisions at T p = 1.2 GeV 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 T p = 1.08-1.36 GeV ( √ s = 2.35-2.46 GeV) covering thus the regions of N * (1440) and (1232) (1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange as well as isospin relations based on the pp → ppπ 0 π 0 data underpredict substantially the measured total cross section. The calculations are also at variance with specific experimental differential cross sections. An isotensor N dibaryon resonance with I (J P ) = 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)] and more recently calculated by A. Gal and H. Garcilazo [Nucl. Phys. A 928, 73 (2014)].

Dibaryons: Molecular versus compact hexaquarks *

“…Kukulin and Platonova have demonstrated recently that, by accounting for the isovector -wave resonances, as well as the dominant isovector resonance, the cross section and polarization observables can be described quantitatively for the first time with formfactor cut-off parameters, which are consistent with those obtained in elastic scattering descriptions [114].…”

“…gular distributions associated with or . These cannot be understood by the conventional -channel reaction mechanism; however, they can be quantitatively described by the presence of with m = 2140(10) MeV and = 110 (10) MeV [115,116]. In addition to the prediction of Dyson and Xuong, Gal and Garcilazo obtain this state with approximately the same mass and width [60], whereas the Nanjing group does not obtain enough binding in their calculation for the formation of a bound state [117].…”

Fully-heavy hexaquarks in a constituent quark model

“…Another six-quark state is the d * (2380) observed by the WASA-at-COSY Collaboration [47,48], and are investigated by several theoretical groups [49][50][51][52][53][54][55][56][57][58][59][60][61][62]. Moreover, other possible structures are also claimed experimentally, such as the isotensor ∆N dibaryon resonance D 21 [63,64] and proton-Ω correlation in heavy-ion collisions [65], and the readers interested in light hexaquarks is referred to the recent review [66,67]. Owing to the complexities of light few-body systems, the nature of d * (2380) is a long-standing problem, which seems intractable and will stay in dispute in the near future.…”