CAS, Inst High Energy Phys, Beijing 100049, Peoples R China
; Chinese Acad Sci, Grad Univ, Beijing 100049, Peoples R China
; Ctr Theoret Nucl Phys, Natl Lab Heavy Ion Accelerator, Lanzhou 730000, Peoples R China
The pp -> nK(+)Sigma(+) reaction is a very good isospin 3/2 filter for studying Delta(++*) decaying to K+Sigma(+). With an effective Lagrangian approach, contributions from a previous ignored sub-K+Sigma(+)-threshold resonance Delta(++*) (1620)1/2(-) are fully included in addition to those already considered in previous calculations. It is found that the Delta(++*)(1620)1/2(-) resonance gives an overwhelmingly dominant contribution for energies very close to threshold, with a very important contribution from the t-channel rho exchange. This solves the problem that all previous calculations seriously underestimate the near-threshold cross section by order(s) of magnitude. Many important implications of the results are discussed. (c) 2007 Elsevier B.V. All rights reserved.